HBB+Unit+1+Clinical+LOs


 * LEARNING OBJECTIVES**
 * Unit I - Back and Extremities**


 * Clinical Content**

1. Define lumbar spinal stenosis and describe the surgical correction (laminectomy) of this abnormality. -“Lumbar spinal stenosis describes a stenotic (narrow) vertebral foramen in one or more lumbar vertebrae…. Stenosis of a lumbar vertebral foramen…may cause compression of one or more of the spinal nerve roots occupying the inferior vertebral canal. Surgical treatment of lumbar stenosis may consist of decompressive laminectomy. … The surgical excision of one or more spinous processes and the adjacent supporting vertebral laminae.” (Clin. Oriented Anat. pp. 457 & 460)

2. Describe the proper anatomical location and rationale for this location when performing the following procedures: (A) Epidural anesthesia – “An anesthetic agent is injected into the extradural (epidural) space using the position described for the lumbar spinal puncture, or through the sacral hiatus.” “In living persons, the sacral hiatus is closed by the membranous **sacrococcygeal ligament**, which is pierced by the //filum terminale// (a connective tissue strand extending from the tip of the spinal cord to the coccyx). Deep (superior) to the ligament, the epidural space of the sacral canal is filled with fatty connective tissue. In **caudal epidural anesthesia** or //caudal analgesia//, a local anesthetic is injected in to the fat of the sacral canal that surrounds the proximal portions of the sacral nerves. This can be accomplished by several routes including the sacral hiatus. … The anesthetic solution spreads superiorly and extradurally where is acts on the S2-Co1 spinal nerves of the cauda equina. The height to which the anesthetic ascends is controlled by the amount injected and the position of the patient. Sensation is lost inferior to the epidural block. Anesthetic agents can also be injected through the posterior sacral foramina into the sacral canal around the spinal nerve roots (**transsacral epidural anesthesia** ).” (COA p. 461 & 506) Caudal epidural anesthesia in childbirth must be administered before actual delivery. (B) **Spinal anesthesia** – “An anesthetic agent is injected into the subarachnoid space. Anesthesia usually occurs with 1 minute.” (COA p. 506) Page 398 of COA refers to spinal anesthesia as a spinal block at the L3-L4 level, while it can be performed higher or lower (dural sac terminates in the sacrum ~S2) as long as it enters the subarachnoid space. Higher levels present the problem of possible injury to the spine and anesthetized paralysis of structures. This anesthesia is quick. A headache may follow. (C) **Lumbar puncture** – “Lumbar puncture, the withdrawal of CSF from the lumbar cistern, is an important diagnostic tool for evaluating a variety of CNS disorders. …LP is performed with the patient lying on the side with the back and hips flexed. Flexion of the vertebral column facilitates insertion of the needle by spreading apart the vertebral laminae and spinous processes, stretching the ligament flava. The skin covering the lower lumbar vertebrae is anesthetized, and a //lumbar puncture needle//, fitted with a //stylet// , is inserted in the midline between the spinous processes of the L3 and L4 (or L4 and L5) vertebrae. Recall that a plane transecting the highest points of the iliac crests—the //supracristal plane// —usually passes through the L4 spinous process. At these levels, there is no danger of damaging the spinal cord.” (COA p 505)

3. Describe the most common causes, anatomical basis and clinical presentation, including physical examination findings (ie straight leg raise test), in a patient with a herniated "disc" (nucleus pulposus). -**Common causes and anatomical basis** : “The IV discs in young persons are strong—usually so strong that vertebrae often fracture during a fall before the discs rupture. Furthermore, the water content of their nuclei pulposi is high (approaching 90%), giving them great turgor (fullness). However, violent **hyperflexion of the vertebral column** may rupture an IV disc and fracture the adjacent vertebral bodies.” “IV discs may also be damaged by violent rotation (e.g. during a golf swing).” “Flexion of the vertebral column produces compression anteriorly and stretching or tension posteriorly, squeezing the nucleus pulposus further posteriorly toward the thinnest part of the annulus fibrosus. If the **anulus fibrosus has degenerated**, the nucleus pulposus may herniate into the vertebral canal and compress the spinal cord or the nerve roots of the cauda equina. “Herniations of the nucleus pulposus usually extend posterolaterally, where the annulus fibrosus is relatively thin and does not receive support from either the posterior or the anterior longitudinal ligaments. A posterolaterally herniated IV disc is more likely to be symptomatic because of the proximity of the spinal nerve roots.” Localized pain (usually acute) => pressure on longitudinal ligaments and anular fibrosus and local inflammation. Chronic pain (usually referred) perceived from the dermatome of affected nerve. ~”95% of lumbar disc protrusions occur at the L4-L5 or L5-S1 levels.” “Symptom producing IV disc protrusions occur almost as often as in the lumbar region.” “Cervical IV disc protusions result in pain in the neck, shoulder, arm and hand.” “The general rule is that when an IV disc protrudes, it usually compresses the nerve root numbered one inferior to the herniated disc; for example, the L5 nerve is compressed by an L4-L5 IV disc herniation.” (COA pp 474-476)
 * Clinical presentation and physical examination findings** : Decreased intervertebral space in radiograph; “pain of acute onset in the lower back is a common presenting symptom”; lumbar region tense and cramped secondary to ischemia and muscle spasm; sciatica -“pain in lower back and hip radiating down the back of the thigh into the leg” (from compromised L5 or S1 part of sciatic nerve) “Any maneuver that stretches the sciatic nerve, such as flexing the thigh with the knee extended (straight leg raising test), may produce or exacerbate (but in some individuals relieves) sciatic pain.

4. Describe the most common abnormal curvatures (ie thoracic kyphosis, lumbar lordosis and scoliosis) of the vertebral column. Can be developmental or pathological. -Excessive thoracic kyphosis: “(hunchback) is characterized by an abnormal increase in the thoracic curvature; the vertebral column curves posteriorly. This abnormality can result from erosion (due to osteoporosis) of the anterior part of one or more vertebrae.” (COA p 480) Leads to significant decrease in pulmonary capacity. Excessive lumbar lordosis: “(hollow back or sway back) is characterized by an anterior tilting of the pelvis (the upper sacrum is flexed or rotated anteroinferiorly—//nutation// ), with an increased extension of the lumbar vertebrae.” (COA pp 480-481) Temporary during late pregnancy and can also be caused by a potbelly in either sex. May cause lower back pain. Scoliosis: “(G., crookedness or curved back) is characterized by //an abnormal lateral curvature// that is accompanied by rotation of the vertebrae. The spinous processes turn toward the cavity of the abnormal curvature, and when the individual bends over, the ribs rotate posteriorly (protrude) on the side of the increased convexity.” 4 types: //structural//, sometimes with kyphosis, (80% of cases are idiopathic – first develops in girls 10-14 and boys 12-15, more common and severe among girls); //myopathic// , asymmetrical weakness of back muscles; //functional// , difference in leg length accompanied by pelvic tilt or herniated IV disc; and //habit// , habitual sitting or standing in improper position (disappears during maximum flexion of spine). “Functional scolioses do not persist once the underlying problem has been effectively treated.” (COA pp 481-482)

5. Describe the anatomical basis for the dermatomal distribution of herpes zoster (shingles) outbreaks. -“A //herpes zoster infection// causes a classic, dermatomally distributed skin lesion— //shingles// —and agonizingly painful condition. Herpes zoster is primarily a viral disease of spinal ganglia, usually a reactivation of the varicella-zoster virus (VZV), or chickenpox virus. After invading a ganglion, the virus produces a sharp burning pain in the dermatome supplied by the involved nerve. The affected skin area becomes red, and vesicular eruptions appear. The pain may precede or follow the skin eruptions. Although primarily a //sensory neuropathy// (pathological change in the nerve), weakness from motor involvement occurs in 05-5.0% of people, commonly in elderly cancer patients. Muscular weakness occurs in the same myotomal distribution, as do the dermatomal pain and vesicular eruptions.” (COA pp 96-97) Thus, an infection in the spinal ganglia causes a pathological change which affects the skin of the nerve’s dermatome.

6. Identify the radiological appearance and describe the most common clinical implications of the following fractures/dislocations: (A) Femoral head dislocation – Femoral head outside of acetabulum, joint capsule ruptures (inferiorly and posteriorly for Posterior and inferiorly in Anterior), acetabulum may fragment, posterior dislocation may injure the sciatic nerve, worry about disrupting blood supply to head of femur and subsequent avascular necrosis. Positive Trendelenburg test. (B) Femoral neck – break at neck of femur, from high-energy impacts or older patients particularly with osteoporosis, often intracapsular, requiring internal skeletal fixation. Lateral rotation occurs, blood supply to head of femur often compromised. Inherently unstable and impaction (overriding of fragments leading to foreshortening of limb) occurs. (C) Greater trochanter of femur – greater trochanter separated from femur, most common from direct trauma during the more active years. Shows a positive Trendelenburg test. (D) Femoral shaft – most common from direct trauma during the more active years, a spiral fracture would result in foreshortening or fracture may be comminuted with fragments displaced (union taking up to 1 year) (E) Tibial shaft – most likely at junction of middle and inferior thirds (where it is narrowest). This area has worst blood supply. Anterior surface is subcutaneous, as such “the tibial shaft is the most common site for a compound fracture.” “Transverse stress fractures of the inferior third of the tibia are common in people who take long hikes before they are conditioned for this activity. The strain may fracture the anterior cortex of the tibia.” “Severe torsion may produce a diagonal fracture of the middle and inferior thirds, as well as a fracture of the fibula…often associated with limb shortening caused by overriding of fractured ends. Frequently during skiing, a fracture results from a high-speed forward fall, with angles the leg over the rigid ski boot, producing a ‘boot-top fracture’.” (COA 527-528) Also Tibial and fibular malleoli fractures are possible with extreme ankle eversion. (F) Calcaneus – “A hard fall onto the heel, from a ladder for example, may fracture the calcaneus into several pieces, producing a comminuted fracture, A calcaneal fracture is usually disabling because it disrupts the subtalar (talocalcaneal) joint, the talus articulates with the calcaneus.” (COA p 529) (G) Talar neck – “Fractures of the talar neck may occur during severe dorsiflexion of the ankle (e.g. when a person is pressing extremely hard on the brake pedal of a vehicle during a head-on collision). In some cases, the body of the talus dislocates posteriorly.” (COA p 529)

7. Define "referred pain" and describe why hip abnormalities can present with knee pain. Referred pain is pain felt that originates in a different area (usually felt as if coming from somewhere with the same nerve. Because the hip and the knee both receive innervation from the sciatic nerve, pain from one area can be referred to the other.

8. Name the most likely ligaments torn in an anterior and posterior hip dislocation. Anterior hip dislocation – iliofemoral ligament (strongest) and pubofemoral ligament and ligamentum teres Posterior hip dislocation (most common) – ischiofemoral ligament (weakest) and ligamentum teres

9. Define coxa vara and coxa valga. -Coxa vara: “The angle of inclination between the long axis of the femoral neck and the femoral shaft varies with age, sex, and development of the femur. … When the angle of inclination is decreased, the condition is coxa vara; when it is increased, it is coxa valga. The term “vara” or “varus” is a Latin adjective describing any bone or joint in a limb that is deformed so that the distal element deviates toward the midline.” Valga or valgus → distal end deviating away from midline. (COA p 526) Right angle femur → coxa vara, straight femur → coxa valga

10. Describe the most common physical examination abnormalities (including the names of specific tests) with sprains/tears of the following knee ligaments: (A) Anterior cruciate ligament – movement in the inferior pulling of the “Anterior drawers test” or movement in the Lachman test.

(B) Posterior cruciate ligament – movement in the pushing during the “Posterior drawers test” (C) Medial collateral ligament – Pain or a gap in the medial joint during the Valgus Stress Test (aka Abduction Stress) (D) Lateral collateral ligament – Pain or a gap in the lateral joint during the Varus Stress Test (aka Adduction Stress) (E) Medial meniscus – Popping or clicking in the McMurray test with the lower leg rotated externally (F) Lateral meniscus – Popping or clicking in the McMurray test with the lower leg rotated internally

11. Describe the most common causes, clinical findings and ligaments injured in medial and lateral ankle sprains. “The ankle is the most frequently injured major joint in the body. //Ankle sprains// (torn fibers of ligaments) are most common. A sprained ankle is nearly always an **//inversion//** //injury//, involving twisting of the weight-bearing plantarflexed foot. The person steps on an uneven surface and the foot is forcibly inverted. //Lateral ligament sprains// occur in sports in which running and jumping are common, particularly basketball. That lateral ligament is injured because it is much weaker than the medial ligament and is the ligament that resists inversion at the talocrural joint. The //anterior talofibular ligament// —part of the lateral ligament—is most vulnerable and most commonly torn during ankle sprains, either partially or completely, resulting in instability of the ankle joint. The //calcaneofibular ligament// may also be torn. In severe sprains, the lateral malleolus of the fibula may be fractured. //Shearing injuries fracture the lateral malleolus// at or superior to the ankle joint. //Avulsion fractures// break the malleolus inferior to the ankle joint; a fragment of bone is pulled off by the attached ligament(s). “A **Pott fracture-dislocation of the ankle** occurs when the foot is forcibly **everted**. This action pulls on the extremely strong medial ligament, often tearing off the medial malleolus. The talus then moves laterally, shearing off the lateral malleolus or, more commonly, breaking the fibula superior to the tibiofibular syndesmosis. If the tibia is carried anteriorly, the posterior margin of the distal end of the tibia is also sheared off by the talus, producing a ‘trimalleolar fracture.’ In applying this term to this injury, the entire distal end of the tibia is erroneously considered to be a ‘malleolus’.” (COA pp 665-666)

- 1 - 12. Define compartment syndrome and compare/contrast the clinical findings and implications in the following compartment syndromes of the lower extremity: “The fascial compartments of the lower limbs are generally closed spaces, ending proximally and distally at the joints. Trauma to muscles and/or vessels in the compartments from burns, sustained intense use of muscles, or blunt trauma may produce hemorrhage, edema, and inflammation of the muscles. Because the septa and deep fascia of the leg forming the boundaries of the leg compartments are strong, the increased volume consequent to any of these processes increases intracompartmental pressure. The pressure may reach levels high enough to compress structures significantly in the compartment(s) concerned. The small vessels of the muscles and the nerves (vasa nervorum) are particularly vulnerably to compression. Structures distal to the compressed area may become ischemic and permanently injured. … Inflammations within the anterior and posterior compartments of the leg spread chiefly in a distal direction. … Loss of distal leg pulses is an obvious sign of arterial compression, as is lowering of the temperature of tissues distal to the compression. … Fasciotomy may be necessary to relieve compartmental pressure and debribe (remove by scraping) pockets of infection.” (COA pp 540 & 605) Pronounced pain when passively stretching muscles, weakness of muscles, inflammation, blockage of blood supply, etc. Can be acute or chronic. (A) Anterior leg: The anterior compartment is especially confined and the most susceptible to compartment syndromes. (Shin splints are a mild form) plantar flexion hurts. (B) Posterior leg: The largest of the three compartments. “The larger **superficial subcompartment** is the least confined compartmental area. The smaller **deep subcompartment,** like the anterior compartment, is bounded by the two leg bones and the interosseus membrane that binds them together, plus the transverse intermuscular septum. Therefore, the deep subcompartment is quite tightly confined. Because the nerve and blood vessels supplying the entire posterior compartment and the sole of the foot pass though the deep subcompartment, when swelling occurs it leads to a compartment syndrome that has serious consequences, such as muscular necrosis (tissue death) and paralysis.” (COA p596) Dorsiflexion hurts.

13. Describe the preferred location for ligating the femoral artery after traumatic laceration near the adductor hiatus. To allow the best circulation to the leg, the femoral artery should be ligated distal to the branching off of the descending genicular artery. This will allow for circulation from both the descending genicular a. and the descending branch of the lateral circumflex femoral a. into the genicular anastimosis.

14. Describe the most common clinical implications of posterior tibial artery stenosis. “The posterior tibial pulse can usually be palpated between the posterior surface of the medial malleolus and the medial border of the calcaneal tendon. Because the posterior tibial artery passes deep to the flexor retinaculum, it is important when palpating this pulse to have the person invert the foot to relax the retinaculum. Failure to do so may lead to the erroneous conclusion that the pulse is absent. “Both arteries are examined simultaneously for equality of force. Palpation of the posterior tibial pulses is essential for examining patients with occlusive //peripheral arterial disease//. Although posterior tibial pulses are absent in approximately 15% of normal young people, absence of posterior tibial pulses is a sign of occlusive peripheral arterial disease in people older than 60 years. For example, //intermittent claudication//, characterized by leg pain and cramps, develops during walking and disappears after rest. These conditions result from ischemia of the leg muscles caused by narrowing of occlusions of the leg arteries.” (COA p 608)

15. Describe the location of a femoral hernia. “The femoral ring is a weak area in the anterior abdominal wall that normally is of a size sufficient to admit the tip of the little finger. The femoral ring is the usual site of a **femoral hernia,** a protrusion of abdominal viscera (often a loop of the small intestine) through the femoral ring into the femoral canal. A femoral hernia appear as a mass, often tender, in the femoral triangle (Inguinal ligament, medial sartorius, aductor longus), i//nferolateral to the pubic tubercle//. The hernia is bounded by the femoral vein laterally and the lacunar ligament medially. The hernial sac compresses the contents of the femoral canal (loose connective tissue, fat, and lymphatics) and distends the wall of the canal. Initially, the hernia is small because it is contained within the canal, but it can enlarge by passing inferiorly through the saphenous opening into the subcutaneous tissue of the thigh.” (COA p 561) –more common in females.

16. Describe the most common physical examination findings and clinical implications with the following injuries: (A) Hamstring injury / evulsion: “Hamstring strains (pulled and/or torn hamstrings) are common in individual who run and/or kick hard (e.g. in running, jumping, and quick-start sports such as baseball, basketball, football, and soccer). The violent muscular exertion required to excel in these sports may avulse (tear) part of the proximal tendinous attachments of the hamstrings to the ischial tuberosity. Hamstring strains are twice as common as quadriceps strains. “Usually thigh strains are accompanied by contusion (bruise) and tearing of muscle fibers, resulting in rupture of the blood vessels supplying the muscles. The resultant //hematoma// is contained by the dense stocking-like fascia lata. “//Tearing of the hamstring fibers// is often so painful when the athlete moves or stretches the leg that the person falls and writhes in pain. These injuries often result from inadequate warming up before practice or competition. “//Avulsion of the ischial tuberosity// at the proximal attachments of the biceps femoris and semitendinosus may result from forcible flexion of the hip with the knee extended.” (COA p 581)

(B) Superior gluteal nerve injury (ie finding of positive Trendelenburg test): “Injury to this nerve results in a characteristic motor loss, resulting in a disabling //gluteus medius limp//, to compensate for weakened abduction of the thigh by the gluteus medius and minimus, and/or a //gluteal gait// , a compensatory list of the body to the weakened gluteal side. This compensation places the center of gravity over the supporting lower limb. Medial rotation of the thigh is also severely impaired. When a standing person is asked to lift one foot off the ground and stand on one foot, the gluteus medius and minimus normally contract as soon as the contralateral foot leaves the floor, preventing tipping of the pelvis to the unsupported side. “When a person who has suffered a lesion of the superior gluteal nerve is asked to stand on one leg, the pelvis on the unsupported side descends, indicating that the gluteus medius and minimus on the supported side are weak or non-functional. This sign is referred to clinically as a //positive Trendelenburg test//. Other causes of this sign include //fracture of the greater trochanter// and //dislocation of the hip joint//. “When the pelvis descends on the unsupported side, the lower limb becomes, in effect, too long and does not clear the ground when the foot is brought forward in the swing phase of walking.” Thus, different gaits (same options as in foot drop). 1) Gluteal gait (or waddling / leaning to one side), 2) steppage gait (high step), or 3) the swing-out gait (swing the foot around/adduction). (COA 581-582)

(C) Sciatic nerve injury (ie finding of a positive straight leg raise test): “A pain in the buttock may result from compression of the sciatic nerve by the piriformis muscle (//piriformis syndrome// ). Individuals involved in sports that require excessive us of the gluteal muscles and women are more likely to develop this syndrome. In approximately 50% of cases, the histories indicate trauma to the buttock associated with hypertrophy and //spasm of the piriformis//, In the approximately 12% of people in whom the common fibular division of the sciatic nerve passes through the piriformis, this muscle may compress the nerve. “Complete section of the sciatic nerve is uncommon. When this injury occurs, the leg is useless because extension of the hip is impaired, as is flexion of the leg. All ankle and foot movement are also lost. “Incomplete section of the sciatic nerve (e.g. from stab wounds) may also involve the inferior gluteal and/or the posterior femoral cutaneous nerve. Recovery from a lesion of the sciatic nerve is slow and usually incomplete.” The medial side of buttock is the side of danger; the lateral side is the side of safety regarding injury to the sciatic nerve and branches to the hamstrings. Flexing the thigh with the knee extended (straight leg raising test) may not be possible with sciatic nerve damage. (COA 582)

(D) Common fibular nerve injury (ie finding of foot drop): “Because of its superficial position, //the common fibular is the nerve most often injured in the lower limb,// mainly because it winds subcutaneously around the fibular neck, leaving it vulnerable to direct trauma. This nerve may also be severed during fracture of the fibular neck or severely stretched when the knee joint is injured or dislocated. //Severance of the common fibular nerve// results in flaccid paralysis of all muscles in the anterior and lateral compartments of the leg. The loss of dorsiflexion of the ankle causes **footdrop**, which is further exacerbated by unopposed inversion of the foot. This has the effect of making the limb ‘too long’: The toes do not clear the ground during the swing phase of walking. There are several other conditions that may result in a lower limb that is ‘too long’ functionally, for example, pelvic tilt and spastic paralysis or contraction of the soleus.” 3 ways to compensate: A waddling gait (leaning), A swing out gait (swing the limb out to the side), and A high-stepping steppage gate (pick up the foot from hip and knee). In fibular nerve injury, the steppage gait is commonly used, sometimes with an extra “kick” at the end. Without the braking of the dorsiflexors, the foot flops as the heel hits. May also lose sensation on anterolateral aspect of leg and dorsum of foot. (COA 605-606)

(E) Tibial nerve injury: “Injury to the tibial nerve is uncommon because of its deep and protected position in the popliteal fossa; however, the nerve may be injured by deep lacerations in the fossa. //Posterior dislocation of the knee joint// may also damage the tibial nerve. //Severance of the tibial nerve// produces paralysis of the flexor muscles in the leg and the intrinsic muscles in the sole of the foot. People with a tibial nerve injury are unable to plantarflex their ankle or flex their toes. Loss of sensation also occurs on the sole of the foot.” (COA 605)

(F) Tibialis anterior strain ("shin splits"): “edema and pain in the area of the distal two thirds of the tibia—result from repetitive microtrauma of TA, which causes small tears in the periosteum covering the shaft of the tibia and/or of fleshy attachments to the overlying deep fascia of the leg. Shin splints are a mild form for the anterior compartment syndrome. Shin splints commonly occur during traumatic injury or athletic overexertion of muscles in the anterior compartment, especially TA, by untrained persons. Often persons who lead sedentary lives develop shin splints when they participate in walk-a-thons. Shin splints also occur in trained runners who do not warm up and cool down sufficiently. Muscles in the anterior compartment swell from sudden overuse, and then edema and muscle-tendon inflammation reduce the blood flow to the muscles. The swollen muscles are painful and tender to pressure.” (COA p 605)

(G) Calcaneal tendonitis and tendon rupture: “Inflammation of the calcaneal tendon constitutes 9-18% of running injuries. Microscopic tears of collagen fibers in the tendon, particularly just superior to its attachment to the calcaneus, result in //tendinitis//, which cause pain during walking, especially when wearing rigid-soled shoes. Calcaneal tendinitis often occurs during repetitive activities, especially in individuals who take up running after prolonged inactivity or suddenly increase the intensity of their training, but it may also result from poor footwear or training surfaces. “Rupture of the calcaneal tendon is often sustained by poorly conditioned people with a history of calcaneal tendinitis. The injury typically experienced as an audible snap during a forceful push off (plantarflexion with knee extended) followed immediately by sudden calf pain and sudden dorsiflexion of the plantarflexed foot. In a completely ruptured tendon, a gap is palpable, usually 1-5 cm proximal to the calcaneal attachment. The muscles affected are the gastrocnemius, soleus, and plantaris.” Probably most severe acute muscular problem of leg. Can’t plantarflex against resistance, ambulation only when limb is externally rotated (putting foot sideways) with no pushing off. Bruising usually occurs around ankle, with a lump in calf from shortened triceps surae. Surgery necessary for active people, otherwise non-surgical repairs can be adequate. (COA 606-607)

(H) Plantar fasciitis: “Inflammation of the plantar fascia – plantar fasciitis—is of the caused by an overuse mechanism. It may result from running and high-impact aerobics, especially when inappropriate footwear is worn. Plantar fasciitis is the most common hindfoot problem in runners. It causes pain on the plantar surface of the foot and heel. The pain is often most severe after sitting and when beginning to walk in the morning. It usually dissipates after 5-10 minutes of activity and recurs again following rest. Point tenderness is located at the proximal attachment of the aponeurosis to the medial tubercle of the calcaneus and on the medial surface of this bone. The pain increases with passive extension of the great toe and may be further exacerbated by dorsiflexion of the ankle and/or weight-bearing. “If a calcaneal spur (abnormal bony process) protrudes from the medial tubercle, plantar fasciitis is likely to cause pain on the medial side of the foot when walking. Usually a bursa develops at the end of the spur that may also become inflamed and tender.” (COA p 624)

17. Identify the radiological appearance and describe the most common clinical implications of the following fractures/dislocation: (A) Clavicle: “The clavicle is one of the most frequently fractured bones. Clavicular fractures are especially common in children and are often caused by an indirect force transmitted from an outstretched hand through the bones of the forearm and arm to the shoulder during a fall. A fracture may also result from a fall directly on the shoulder. The weakest part of the clavicle is the junction of its middle and lateral thirds. “After fracture of the clavicle, the sternocleidomastoid muscle elevates the medial fragment of bone. Because of the subcutaneous position of the clavicles, the end of the superiorly directed fragment is apparent. The trapezius muscle is unable to hold the lateral fragment up owing to the weight of the upper limb, and thus the shoulder drops. The strong coracoclavicular ligament usually prevents dislocation at the AC joint. People with fractured clavicles support the sagging limb with the other limb. In addition to being depressed, the lateral fragment of the clavicle may be pulled medially by the adductor muscles of the arm, such as the pectoralis major. Overriding of the bone fragments shortens the clavicle.” (COA p 684)

(B) Acromioclavicular: “Although its extrinsic coracoclavicular ligament is strong, the AC joint itself is weak and easily injured by a direct blow. In contact sports such as football, soccer, hockey, or the martial arts, it is not uncommon for //dislocation of the AC joint// to result from a hard fall on the shoulder or on the outstretched upper limb. Dislocation of the AC joint can also occur when an ice hockey player is driven into the boards or when a person receives a severe blow to the superolateral part of the back. An AC joint dislocation, often called a ‘shoulder separation’ is severe when both the AC and coracoclavicular ligaments are torn. When the coracoclavicular ligament tears, the shoulder separates from the clavicle and falls because of the weight of the upper limb. //Rupture of the coracoclavicular ligament// allows the fibrous layer of the joint capsule to be torn so that the acromion can pass inferior to the acromial end of the clavicle. Dislocation of the AC joint makes the acromion more prominent, and the clavicle may move superior to this process.” (COA pp 813-814)

(C) Glenohumeral: “Because of its freedom of movement and instability, the glenohumeral joint is commonly dislocated by direct or indirect injury. Because the presence of the coraco-acromial arch and the support of the rotator cuff are effective in preventing upward dislocation, most dislocations of the humeral head occur in the downward (inferior) direction. However, they are described clinically as anterior or (more rarely) posterior dislocations, indicating whether the humeral head has descended anterior or posterior to the infraglenoid tubercle and the long head of the triceps. The head ends up lying anterior or posterior to the glenoid cavity. “**Anterior dislocation of the glenohumeral joint** occurs most often in young adults, particularly athletes. It is usually caused by excessive extension and lateral rotation of the humerus. The head of the humerus is driven inferoanteriorly, and the fibrous layer of the joint capsule and glenoid labrum may be stripped from the anterior aspect of the glenoid cavity in the process. A hard blow to the humerus when the glenohumeral joint is fully abducted tilts the head of the humerus inferiorly onto the inferior weak part of the joint capsule. This may tear the capsule and dislocate the shoulder so that the humeral head comes to lie inferior to the glenoid cavity and anterior to the infraglenoid tubercle. The strong flexor and adductor muscles of the glenohumeral joint usually subsequently pull the humeral anterosuperiorly into a subcoracoid position. Unable to use the arm, the person commonly supports it with the other hand. “**Inferior dislocation of the glenohumeral joint** often occurs after an avulsion fracture of the greater tubercle, owing to the absence of the upward and medial pull produced by the muscles attaching to the tubercle.” (COA p 814-815)

(D) Humeral neck: “Most injuries of the proximal end of the humerus are //fractures of the surgical neck//. These injuries are especially common in elderly people with osteoporosis, whose demineralized bones are brittle. Humeral fractures often result in one fragment being driven into the spongy bone of the other fragment (**impacted fracture** ). The injuries usually result from a minor fall on the hand, with the force being transmitted up the forearm bones of the extended limb. Because of impaction of the fragments, the fracture site is sometimes stable and the person is able to move the arm passively with little pain.”

(E) Humeral shaft: “A //transverse fracture of the shaft of the humerus// frequently results from a direct blow to the arm. The pull of the deltoid muscle carries the proximal fragment laterally. Indirect injury resulting from a fall on the out-stretched hand may produce a //spiral fracture of the humeral shaft//. Overriding of the oblique ends of the fractured bone may result in foreshortening. Because the humerus is surrounded by muscles and has a well-developed periosteum, the bone fragments usually unite well.” “A midhumeral fracture may injure the radial nerve in the radial groove. When this nerve is damaged, the fracture is not likely to paralyze the triceps because of the high origin of the nerves to two of its three heads. …When the nerve is injured in the radial groove,… the muscles in the posterior compartment of the forearm that are supplied by the more distal branches of the nerve are paralyzed.” Thus, wrist drop. “The following parts of the humerus are in direct contact with the indicated nerves: Surgical neck→axillary nerve, Radial groove→radial nerve, Distal end of humerus→median nerve, Medial epicondyle→ulnar nerve” (COA pp 684-685, 742-743)

(F) Ulnar olecranon: “Fracture of the olecranon, called a ‘fractured elbow’ by laypersons, is common because the olecranon is subcutaneous and protrusive. The typical mechanism of injury is a fall on the elbow combined with sudden powerful contraction of the triceps brachii. The fractured olecranon is pulled away by the active and tonic contraction of the triceps, and the injury is often considered to be an avulsion fracture, Because of the traction produced by the tonus of the triceps on the olecranon fragment, pinning is usually required, Healing occurs slowly, and often a cast must be worn for an extended period of time.” (COA 766) “//Posterior dislocation of the elbow joint// may occur when children fall on their hands with their elbows flexed. Dislocations of the elbow my result from hyperextension or a blow that drives the ulna posterior or posterolateral. The distal end of the humerus is driven though the weak anterior part of the fibrous layer of the joint capsule as the radius and ulna dislocate posteriorly. The ulnar collateral ligament is often torn, and an associated fracture of the head of the radius, coronoid process, or olecranon process of the ulna may occur. Injury to the ulnar nerve may occur, resulting in numbness of the little finger and weakness of flexion and adduction of the wrist.” (COA p 817)

(G) Ulnar shaft: “Fractures of both the radius and the ulna are usually the result of severe injury. A direct injury usually produces transverse fractures at the same level, usually the middle third of the bones. Isolated fractures of the radius or ulna also occur. Because the shafts of these bones are firmly bound together by the interosseous membrane, a fracture of one bone is likely to be associated with dislocation of the nearest joint.” (COA p 685)

(H) Radial shaft: see Ulnar shaft.

(I) Colles: “//Fracture of the distal end of the radius// is a common fracture in adults >50 years of age and occurs more frequently in women because their bones are more commonly weakened by osteoporosis. A complete transverse fracture of the distal 2 cm of the radius, called a **Colles fracture**, is the most common fracture in the forearm. The distal fragment is displaced dorsally and is often **comminuted**. The fracture results from forced dorsiflexion of the hand, usually as the result of trying to ease a fall by out-stretching the upper limb. “Often the ulnar styloid process is avulsed (broken off). Normally the radial styloid process projects farther distally than the ulnar styloid; consequently, when a Colles fracture occurs, this relationship is reversed because of the shortening of the radius. This clinical condition is often referred to as a //dinner fork deformity// because a posterior angulation occurs in the forearm just proximal to the wrist and the normal anterior curvature of the relaxed hand. The posterior bending is produced by the posterior displacement and tilt of the distal fragment of the radius. “The typical history of a person with a Colles fracture includes slipping or tripping and, in an attempt to break the fall, landing on the outstretched limb with the forearm and hand pronated. Because of the rich blood supply to the distal end of the radius, bony union is usually good.” (COA pp 685 & 686)

(J) Scaphoid: “The scaphoid is the most frequently fractured carpal bone. It often results from a fall on the palm when the hand is abducted, the fracture occurring across the narrow part of the scaphoid. Pain occurs primarily on the lateral side of the wrist, especially during dorsiflexion and abduction of the hand. Initial radiographs of the wrist may not reveal a fracture; often this injury is (mis)diagnosed as a //severely sprained wrist//. Radiographs taken 10-14 days later reveal a fracture because bone resorption has occurred there. Owing to the poor blood supply to the proximal part of the scaphoid, union of the fractured parts may take at least 3 months. //Avascular necrosis of the proximal fragment of the scaphoid// (pathological death of bone resulting from inadequate blood supply) may occur and produce //degenerative joint disease of the wrist//. In some cases, it is necessary to fuse the carpals surgically (**arthrodesis** ).” (COA p. 686)

(K) Lunate: “//Anterior dislocation of the lunate// is and uncommon but serious injury that usually results from a fall on the dorsiflexed wrist. The lunate is pushed out of its place in the floor of the carpal tunnel toward the palmar surface of the wrist. The displaced lunate may compress the median nerve and lead to //carpal tunnel syndrome//. Because of its poor blood supply, //avascular necrosis of the lunate// may occur. In some cases, excision of the lunate may be required. In //degenerative joint disease of the wrist//, surgical fusion of the carpals (arthrodesis) may be necessary to relieve the severe pain.” (COA p. 817)

18. Describe the impingement test and name the group of muscles most commonly injured when this test is positive. Neer’s impingement test - Examiner presses on the scapula to prevent motion; Examiner raises the patient’s arm in flexion with other hand. Pain with this movement is a positive test and indicates a possible rotator cuff tear.

19. Describe the most common cause of biceps tendonitis and rupture of the biceps long head tendon. Describe the most common clinical presentation of biceps long head tendon rupture. “The tendon of the long head of the biceps is enclosed by a synovial sheath and moves back and forth in the intertubercular sulcus of the humerus. Wear and tear of this mechanism can cause shoulder pain. Inflammation of the tendon (**biceps tendinitis** ), usually the result of repetitive microtrauma, is common in sports involving throwing (e.g. baseball and cricket) and use of a racquet (e.g. tennis). A tight, narrow, and/or rough intertubercular sulcus may irritate and inflame the tendon, producing tenderness and **crepitus** (a crackling sound.)” “Rupture of the tendon (of the long head) usually results from wear and tear of an inflamed tendon as it moves back and forth in the intertubercular sulcus of the humerus. This injury usually occurs in individuals >35 years of age. Typically, the tendon is torn from its attachment to the supraglenoid tubercle of the scapula. The rupture is commonly dramatic and is associated with a snap or pop. The detached muscle belly forms a ball near the center of the distal part of the anterior aspect of the arm (Popeye deformity). Rupture of the biceps tendon may result from forceful flexion of the arm against excessive resistance, as occurs in weight lifters. However, the tendon ruptures more often as the result of prolonged tendinitis that weakens it. The rupture results from repetitive overhead motions, such as occurs in swimmers and baseball pitchers, which tear the weakened tendon where it passes through the intertubercular sulcus.” (COA pp 741-742)

20. Describe the clinical implications of lateral epicondylitis ("tennis elbow") and olecranon bursitis. “Elbow tendinitis (‘tennis elbow’) is a painful musculoskeletal condition that may follow repetitive use of the superficial extensor muscles of the forearm. Pain is felt over the lateral epicondyle and radiates down the posterior surface of the forearm. People with elbow tendinitis often feel pain when they open a door or lift a glass. Repeated forceful flexion and extension of the wrist strain the attachment of the common extensor tendon, producing inflammation of the periosteum of the lateral epicondyle (//lateral epicondylitis)// .” (COA p 766) “The subcutaneous olecranon bursa is exposed to injury during falls on the elbow and to infection from abrasions of the skin covering the olecranon. Repeated excessive pressure and friction, as occurs in wrestling, for example, may cause this bursa to become inflamed, producing a friction **subcutaneous olecranon bursitis** (e.g. student’s elbow). This type of bursitis is also known as ‘dart thrower’s elbow’ and ‘miner’s elbow.’ Occasionally, the bursa becomes infected and the area over the bursa becomes inflamed. “**Subtendinous olecranon bursitis** is much less common. It results from excessive friction between the trips tendon and olecranon, for example, resulting from repeated flexion-extension of the forearm as occurs during certain assembly-line jobs. The pain is most severe during flexion of the forearm because of pressure exerted on the inflamed subtendinous olecranon bursa by the triceps tendon.” (COA pp 815-816)

21. Define Dupuytren contracture. “//Dupuytren contracture// is a disease of the palmar fascia resulting is progressive shortening, thickening, and fibrosis of the palmar fascia and aponeurosis. The fibrous degeneration of the longitudinal bands of the palmar aponeurosis on the medial side of the hand pulls the 4th and 5th fingers into partial flexion at the metacarpophalangeal and proximal interphalangeal joints. “The contracture is frequently bilateral and is seen in some men >50 years of age. Its cause is unknown, but evidence points to a hereditary predisposition. The disease first manifests as painless nodular thickenings of the palmar aponeurosis that adhere to the skin, Gradually, progressive contracture of the longitudinal bands produces raised ridges in the palmar skin that extend from the proximal part of the hand to the base of the 4th and 5th fingers. Treatment of Dupuytren contracture usually involves surgical excision of all fibrotic parts of the palmar fascia to the fingers.” (COA p 789)

22. Define tenosynovitis and describe the anatomical basis for pattern of spread (via synovial sheaths) of infections in the wrist, palm and fingers. “Injuries such as a puncture of a finger by a rusty nail can cause infection of the digital synovial sheaths. When inflammation of the tendon and synovial sheath occurs (**tenosynovitis** ), the digit swells and movement becomes painful. Because the tendons or the 2nd 3rd and 4th fingers nearly always have separate synovial sheaths, the infection is usually confined to the infected finger. If the infection is untreated, however, the proximal ends of these sheaths may rupture, allowing the infection to spread to the midpalmar space. “Because the synovial sheath of the little finger is usually continuous with the common flexor sheath, tenosynovitis in this finger may be spread to the common flexor sheath and thus through the palm and carpal tunnel to the anterior forearm, draining into the space between the pronator quatratus and the overlying flexor tendons (Parona space). Likewise, tenosynovitis in the thumb may spread via the continuous synovial of the FPL (radial bursa). How far an infection spreads from the fingers depends on variations in their connections with the common flexor sheath. “The tendons of the APL and EPB are in the same tendinous sheath on the dorsum of the wrist. Excessive friction of these tendons on their common sheath results in fibrous thickening of the sheath and stenosis of the osseofibrous tunnel. The excessive friction is caused by repetitive forceful use of the hands during gripping and wringing (e.g. squeezing water out of clothes). This condition, called **Quervain tenovagitis stenosans**, causes pain in the wrist that radiates proximally to the forearm and distally toward the thumb. Local tenderness is felt over the common flexor sheath on the lateral side of the wrist. “Thickening of a fibrous digital sheath on the palmar aspect of the digit produces stenosis of the osseofibrous tunnel, the result of repetitive forceful use of the fingers. If the tendons of the FDS and FDP enlarge proximal to the tunnel, the person is unable to extend the finger. When the finger is extended passively, a snap is audible. Flexion produces another snap as the thickened tendon moves. This condition is call digital tenovaginitis stenosans (//trigger finger// or snapping finger). (COA pp 789-790)

- 2 - 23. Describe the most common causes, anatomical basis and clinical implications of the following common nerve injuries: (A) Erb-Duchenne (upper brachial plexus injury) palsy: “Injuries to the superior part of the brachial plexus (C5 & C6) usually result from an excessive increase in the angle between the neck and shoulder. These injuries can occur in a person who is thrown from a motorcycle or a horse and lands on the shoulder in a way that widely separates the neck and shoulder. When thrown, the person’s shoulder often hits something (e.g. a tree of the ground) and stops, but the head and trunk continue to move. This stretches or ruptures superior parts of the brachial plexus or **avulses** (tears) the roots of the plexus from the spinal cord. Injury to the superior trunk of the plexus is apparent by the characteristic position of the limb (‘waiter’s tip position’), in which the limb hangs by the side in medial rotation. //Upper brachial plexus injuries// can also occur in a newborn when excessive stretching of the neck occurs during delivery. “As a result of //injuries to the superior parts of the brachial plexus (Erb-Duchenne palsy// ), paralysis of the muscles of the shoulder and arm supplied by the C5 and C6 spinal nerves occurs: deltoid, biceps, and brachialis. The usual clinical appearance is an upper limb with and adducted shoulder, medially rotated arm, and extended elbow. The lateral aspect of the forearm also experiences some loss of sensation. Chronic microtrauma to the superior trunk of the brachial plexus from carrying a heavy backpack can produce motor and sensory deficits in the distribution of the musculocutaneous and radial nerves. A //superior brachial plexus injury// may produce muscle spasms and a severe disability in hikers ( //backpacker’s palsy// ) who carry heavy backpacks for long periods.” “//Acute brachial plexus neuritis (brachial plexus neuropathy// ) is a neurologic disorder of unknown cause that is characterized by the sudden onset of severe pain, usually around the shoulder. Typically, the pain begins at night and is followed by muscle weakness and sometimes muscular atrophy (neurologic amyopathy). Inflammation of the brachial plexus (brachial neuritis) is often preceded by some event (e.g. upper respiratory infection, vaccination, or non-specific trauma). The nerve fibers involved are usually derived from the superior trunk of the brachial plexus.” (COA pp 729-730)

(B) Klumpke (lower brachial plexus injury) palsy: “//Injuries to the inferior parts of the brachial plexus (Klumpke paralysis// ) are much less common. Inferior brachial plexus injuries may occur when the upper limb is suddenly pulled superiorly—for example, when a person grasps something to break a fall or a baby’s upper limb is pulled excessively during delivery. These events injure the inferior trunk of the brachial plexus (C8 and T1) and may avulse the roots of the spinal nerves from the spinal cord. The short muscles of the hand are affected, and a //claw hand// results.” (COA p 730)

(C) Long thoracic nerve: “When the serratus anterior is paralyzed owning to //injury of the long thoracic nerve//, the medial border of the scapula moves laterally and posteriorly away from the thoracic wall, giving the scapula the appearance of a wing, especially when the person leans on a hand or presses the upper limb against a wall. When the arm is raised, the medial border and inferior angle of the scapula pull markedly away from the posterior thoracic wall, a deformation known as a **winged scapula**. In addition the upper limb may not be able to be abducted above the horizontal position because the serratus anterior is unable to rotate the glenoid cavity superiorly to allow complete abduction of the limb. Remember the trapezius also helps raise the arm above horizontal. Although protected with limbs are at one’s sides, the long thoracic nerve is exceptional in that it courses on the superficial aspect of the serratus anterior, which it supplies. The when the limbs are elevated, as in a knife fight, the nerve is especially vulnerable. Weapons, including bullets directed toward the thorax, are a common source of injury.” (COA pp 709-710)

(D) Spinal accessory nerve: “The primary clinical manifestation of //spinal accessory nerve palsy// is a marked ipsilateral weakness when the shoulders are elevated (shrugged) against resistance.

(E) Thoracodorsal nerve: “Surgery in the inferior part of the axilla puts the throacodorsal nerve (C6-C8) supplying the latissimus dorsi at risk of injury. This nerve passes inferiorly along the posterior wall of the axilla and enters the medial surface of the latissimus dorsi close to where it becomes tendinous. The thoracodorsal nerve is also vulnerable to injury d ring mastectomies with the axillary tail of the breast is removed. The nerve is also vulnerable during surgery on scapular lymph nodes because its terminal part lies anteriorly to them and the subscapular artery. “The latissimus dorsi and the inferior part of the perctoralis major form an anteroposterior muscular sling between the trunk and the arm; however, the latissimus dorsi forms the more powerful part of the sling. With paralysis of the latissimus dorsi, the person is unable to raise the trunk with the upper limbs, as occurs during climbing. Furthermore, the person cannot use an axillary crutch because the shoulder is pushed superiorly by it. These are the primary activities for which active depression of the scapula is required; the passive depression provided by gravity is adequate for most activities.” (COA p 710)

(F) Suprascapular nerve: “The suprascapular nerve is vulnerable to injury in fractures of the middle third of the clavicle. Injury of this nerve results in the loss of lateral rotation of the humerus at the glenohumeral joint. Consequently the relaxed limb rotates medially into the //waiter’s tip// //position//. The ability to initiate abduction of the limb is also affected.

(G) Axillary nerve: The axillary nerve may be injured when the glenohumeral joint dislocates because of its close relation to the inferior part of the joint capsule. The subglenoid displacement of the head of the humerus into the quadrangular space damages the axillary nerve. Axillary nerve injury is indicated by paralysis of the deltoid (manifest as an inability to abduct the arm to or above the horizontal level) and loss of sensation in a small area of skin covering the central part of the deltoid.” (COA p 815) See also COA p 710 → Also injured during fracture of the surgical neck of humerus or by compression resulting from incorrect use of crutches.

24. Describe the most common clinical implications of injury to the radial nerve in the radial groove of the humerus. “Injury to the radial nerve superior to the origin of its branches to the triceps brachii results in //paralysis of the triceps, brachioradialis, supinator, and extensor muscles of the wrist and fingers.// Loss of sensation in areas of skin supplied by this nerve also occurs. “When the nerve is injured in the radial groove, the triceps is usually not completely paralyzed but only weakened because only the medial head is affected; however, the muscles in the posterior compartment of the forearm that are supplied by more distal branches of the nerve are paralyzed. The characteristic clinical sign of radial nerve injury is **wrist-drop** —inability to extend the wrist and the fingers at the metacarpophalangeal joints. Instead, the relaxed wrist assumes a partly flexed position owing to unopposed tonus of flexor muscles and gravity.” (COA p 743)

25. Describe the clinical basis, clinical presentation and physical examination abnormalities (ie Tinel and Phalen tests) for carpal tunnel syndrome. “Carpal tunnel syndrome results from any lesion that significantly reduces the size of the carpal tunnel or, more commonly, increases the size of some of the nine structures or their coverings that pass through it (e.g. inflammation of synovial sheaths). Fluid retention, infection, and excessive exercise of the fingers may cause swelling of the tendons or their synovial sheaths. The median nerve is the most sensitive structure in the tunnel. The median nerve has two sensory branches that supply the skin of the hand; hence **paresthesia** (tingling), **hypoesthesia** (diminished sensation), or **anesthesia** (absence of sensation) may occur in the lateral three and a half digits. The palmar cutaneous branch of the median nerve arises proximal to and does not pass through the carpal tunnel; thus sensation in the central palm remains unaffected. The nerve also has one terminal motor branch, the recurrent branch, which serve the three thenar muscles. “Progressive loss of coordination and strength in the thumb (owing to weakness of the APB and opponens pollicis) may occur if the cause of compression is not alleviated. Individuals with carpal tunnel syndrome are unable to oppose the thumb and have difficult buttoning a shirt or blouse as well as gripping things such as a comb. As the condition progresses, sensory changes radiate into the forearm and axilla. Symptoms of compression can be reproduced by compression of the median nerve with your finger at the wrist for approximately 30 seconds. To relieve both compression and the resulting symptoms, partial or complete surgical division of the flexor retinaculum, a procedure called **carpal tunnel release**, may be necessary. The incision for carpal tunnel release is made toward the medial side of the wrist and flexor retinaculum to avoid possible injury to the recurrent branch of the median nerve.” (COA p 790) Tinel’s sign – percuss median nerve lightly with finger at the base of hand/top of wrist, light tingling is ok, real pain is indicative of carpal tunnel syndrome. Phalen’s test – hold patient’s wrists in acute flexion for 60 seconds OR ask patient to press the backs of both hands together to form right angles. Check sensation – assess for numbness and tingling. Numbness, tingling, and pain are indicative of carpal tunnel syndrome. (from SPETA outlines)

26. Describe the anatomical basis and clinical presentation of median nerve pronator syndrome. “Pronator syndrome, a nerve entrapment syndrome, is caused by compression of the median nerve near the elbow. The nerve may be compressed between the heads of the pronator teres as a result of trauma, muscular hypertrophy, or fibrous bands. Individuals with this syndrome are first seen clinically with pain and tenderness in the proximal aspect of the anterior forearm and hypesthesia of palmar aspects of the radial three and a half digits and adjacent palm. Symptoms often follow activities that involve repeated pronation.” (COA p 768)

27. Describe the most common physical exam findings and clinical implications of an ulnar nerve injury in the wrist. “//Compression of the ulnar nerve// may occur at the wrist where it passes between the pisiform and the hook of the hamate. The depression between these bones is converted by the pisohamate ligament into an osseofibrous tunnel, the ulnar canal (Guyun tunnel). **Ulnar canal syndrome** (Guyun tunnel syndrome) is manifest by hypoesthesia in the medial one and a half fingers and weakness of the intrinsic muscles of the hand. “’Clawing’ of the 4th and 5th fingers (hyperextension at the metacarpophalangeal joint with flexion at the proximal interphalangeal joint may occur, but—in contradistinction to proximal ulnar nerve injury—their ability to flex is unaffected, and there is no radial deviation of the hand.” (COA p 792)

28. Identify where the axillary artery should be ligated to cut off blood supply to the arm. “The axillary artery can be palpated in the inferior part of the lateral wall of the axilla. Compression of the third part of this artery against the humerus (or ligation) may be necessary when profuse bleeding occurs (e.g. resulting from a stab or bullet wound in the axilla). If compression is required at a more proximal site, the axillary can be compressed at its origin (as the subclavian artery crosses the 1st rib) by exerting downward pressure in the angle between the clavicle and the inferior attachment of the sternocleidomastoid.” (COA p 728)

29. Identify where the brachial artery may be clamped to control hemorrhage without producing tissue damage. “Stopping bleeding through manual or surgical control of blood is called **hemostasis**. The best place to compress the brachial artery to control hemorrhage is medial to the humerus near the middle of the arm. Because the arterial anastomoses around the elbow provide a functionally and surgically important collateral circulation, the brachial artery may be clamped distal to the origin of the deep artery of the arm without producing tissue damage. The anatomical basis for this procedure is that the ulnar and radial arteries will still receive sufficient blood through the anastomoses around the elbow.” (COA p 742) “Paralysis of muscles results from ischemia of elbow and forearm within a few hours. Muscles and nerves can tolerate up to 6 hours of ischemia”. (see more on p 742)

30. Describe how synovial inflammation and destruction (such as rheumatoid arthritis) can alter function of the extensor tendons of the hand and cause them to act as digit flexors. “Rheumatoid arthritis causes a proliferation of synovial membranes which produce enzymes that breakdown collagen in cartilage, tendon and ligaments. The destruction of selective tendinous tissue by this disease” can cause the tendons to slip to one side of the MP joints, so that when the extensors are employed, tension basically bowstrings the distal attachment so slight flexion occurs. (Clinical Case 6)


 * Lecture Sessions**

__Human Body Block Orientation__ 1. Describe the block organization and daily schedule. 2. Describe the resources available for learning the block content. 3. Describe the assessment process and block grade. 4. Discuss the learning objectives and their role in the assessment process. 5. Demonstrate professional behavior by being punctual, responsible and courteous while attending and participating in lectures, lecture hall discussions, small group sessions and laboratories **(General Block Objective)**. 6. Give and receive constructive feedback on academic and professional performance including course and instructor evaluations **(General Block Objective)**. 8. Participate in the education of fellow students **(General Block Objective)**. 9. Demonstrate the ability to locate and learn anatomical and clinical knowledge not presented in a lecture setting **(General Block Objective)**.
 * 7** . Communicate effectively with fellow students and faculty in interactive learning activities **(General Block Objective)**.

- 3- __Introduction to Anatomy__ 1. Describe the anatomical position and the imaginary planes (median, sagittal, coronal and transverse) that pass through the body in the anatomical position. -Anatomical position: human body erect, with arms to side in supine position, thumbs out Median – divides the body into right and left halves (sagittal is parallel to median) Coronal – (frontal) divides the body into front and back parts Horizontal (transverse) – divides the body into upper and lower parts

2. Describe the various terms of relationship (and comparison) used to compare the relative position of two structures with each other (anterior [ventral] / posterior [dorsal]; medial / lateral; superior [rostral] / inferior [caudal]; proximal / distal and superficial / deep). Anterior [ventral] – closer to front along the coronal axis / posterior [dorsal] – further behind along the coronal axis Medial – closer the median axis / lateral – further from the median axis Superior [rostral] – higher (closer to top of head) along transverse axis / inferior [caudal] – lower along transverse axis Proximal – in context of extremities: closer to trunk / distal – further away from trunk Superficial – closer to surface / deep – closer to the crossing of the anterior [ventral] / posterior [dorsal] axis and with the median axis of body or limb

3. Discuss the etymological basis of anatomical terminology. Terminology usually adapted from Latin or Greek based on appearance, location, or function

__Tissues and Systems- I - III__ 1. //Describe the structural organization of skin tissue; in particular how are the epidermis, the dermis, and fatty tissue layers related to each other.// 2. //Describe the primary differences between thick (glabrous) skin and thin (hairy) skin.// 3. //Compare and contrast the basic structure, function and anatomical location of superficial and deep fascias.// 4. //Compare and contrast the basic structure, function and anatomical location of the three types of cartilage.// //Hyaline – “no blood supply, no lymphatics, no innervation; thickest at periphery of concave surfaces and in central portions of convex surfaces; composed of type 2 collagen, water, proteoglycans, chondrocytes”, , Hyaline cartilage exists on the ventral ends of ribs; in the larynx, trachea, and bronchi; and on the articular surface of bones.// //Elastic – contains elastic fiber networks and collagen fibers. histologically is similar to hyaline cartilage but contains a plethora of elastic fibers. The principal protein is elastin. / Gives great flexibility so that it is able to withstand repeated bending / outer ear, larynx, and epiglottis// //Fibrocartliage – made up of fibrous connective tissue arranged in bundles, with chondrocytes between the bundles, is the only type of cartilage that contains type I collagen in addition to the normal type II. / / pubic symphysis, intervertebral discs, meniscus, head of the mandible and annulus fibrosus//

5. Compare and contrast the basic structure and function of synovial and solid joints. -Synovial joints: Articular cartilage with synovial membrane and fluid in joint cavity and reinforcing ligaments, presence of joint space allows wide range of motion Solid joints: “No joint space present; provides structural integrity and minimal movement. May be fibrous (cranial sutures, bonds between roots of teeth and jaw bones) or cartilaginous (manubriosternalis and pubic)” (http://www.pathologyoutlines.com/jointspf.html)

6. Discuss the basis for synovial joint nomenclature. Named for what they do or how they look Sellar (i.e. saddle joint) (e.g. Sternoclavicular, carpometacarpal joint of the thumb) Plane or gliding (e.g. Sacroiliac, Proximal tibiofibular) Ginglymus or hinge (e.g. Interphalangeal, Elbow, Talocrural) Pivot or trochoid (e.g. Proximal radio-ulnar, Distal radio-ulnar) Ellipsoidal (e.g. Metatarsophalangeal, Radiocarpal) Ball & socket (e.g. shoulder, hip) Bi-condylar (e.g. knee)

7. //At a basic level, describe the structure, gross appearance and function of bone.// 8. //At a basic level, discuss how bone remodeling leads to the formation of the bony landmarks studied in the anatomy lab.// 9. Define the following terms: diaphysis; epiphysis; traction epiphysis; epiphysial plate; and epiphysial line. Discuss how these terms relate to adult bones. -Diaphysis: shaft of the bone, primary center of ossification Epiphysis: the part of a bone that develops from a secondary ossification center. Epiphysial plate: “a cartilage plate … between the diphyseal and epiphyseal ossification centers. … In long bones an epiphyseal plate is found on each extremity; in smaller bones, such as the phalanges, it is found only at one extremity; and in irregular bones, such as the vertebrae, one or more primary centers of ossification and usually several secondary centers are present.” (Langman’s) Allows for the longitudinal growth of a long bone. Epiphysial line: When growth stops the epiphysis and diaphysis fuse (synostosis) and an epiphyseal line remains.

10. Describe the classification of muscle and where the three types of muscle are located in the body. -Skeletal muscle – strong, quick, discontinuous voluntary contraction, striated, attached at either or both extremities to bone Smooth muscle – weak, slow, involuntary contraction, non-striated found within the tunica media layer of large and small arteries and veins, the bladder, uterus, male and female reproductive tracts, gastrointestinal tract, respiratory tract, the ciliary muscle, and iris of the eye. Cardiac muscle – characterized by strong, fast, continuous involuntary contractions, found in the myocardium of the hearth,, composed of striated but involuntary muscle fibers.

11. Discuss the basic functions of skeletal muscle. -Move joints (exert a force through contraction), stabilize joints (provide stability for body posture), provide body heat through respiration (shiver when cold)

12. Discuss the basis for skeletal muscle nomenclature. Nomenclature is typically based on one or more the following characteristics: -Attachments (flexor **carpi** ulnaris) -Function (**extensor** digitorum) -Appearance (**biceps** brachii, **deltoid**, pronator **teres** )

13. //In very general terms, describe the process by which the depolarization of a motor neuron leads to the contraction of a skeletal muscle fiber.// 14. //Describe the fascicular arrangement of muscle fibers and how the fascicles relate to the three connective tissue layers (endo- peri- and epimysium) associated with skeletal muscle.// 15. //Compare and contrast the gross appearance and general function of muscles having a parallel or a pennate fiber orientation.//

__Introduction to the VHD__ 1. Describe the Visible Human Dataset, its advantages and shortcomings, and how it can best be utilized in the Human Body block and carried forward into other blocks and your career. Discuss the resolution, authenticity, normalization and virtuality of the Visible Human DataSet. 2. Describe the organization and structure of the VH Dissector as a window into the Visible Human and your patient for the next four years. Discuss the different modes of anatomical presentation covering systemic, regional, cross sectional, and surface approaches.

- 4 - 3. Describe the basic methods for accessing structures in the VH Dissector and how they will be used in different situations. Discuss the use of Regional organization to best mimic the dissection laboratory, System hierarchy to parallel classroom presentations, Index and Search for immediate access to a specific structure and Cross Sections for an appreciation of clinical imaging. 4. Describe how to use lessons in the VH Dissector for learning. Discuss the lessons designed to accompany the Dissection Laboratory and the organization used for integration of skeletal, soft tissue, and visceral structures and clinical imaging. 5. Describe features in the VH Dissector for self-testing. Discuss the use of skin opacity for testing surface anatomy concepts and the use of identification labels for reinforcing structure identification. Discuss the hierarchy of both the Index of structure names and the System descriptions and how it can be used to review complete systems.

__Tissues and Systems- IV & V (Circulatory)__ 1. //In general terms, describe the structure, organization, and function of the three basic layers (tunics) of blood vessels//. //- Tunica intima: thinnest, single layer of flattened epithelial cells and a thin connective tissue layer (internal elastic lamina), innermost layer// //Tunica media: the thickest layer, intermediate layer of elastic fibers and smooth muscle, relatively larger in arteries than veins// //Tunica adventitia: made up of connective tissue, outer supporting layer//

2. //In general terms, discuss the morphological characteristics that distinguish the different types of blood vessels.//

3. Discuss the general structure and functional significance of portal systems, anastomoses and end arteries. - Portal system- A vascular pattern with two capillary beds in series (example- hepatic portal system). Important to carry blood directly from one capillary bed to the next before mingling with the rest of the blood flow (thus helping to channel nutrients, etc. to the liver before joining common circulation. Anastomosis- A natural communication, direct or indirect, between two blood vessels (arteries lack valves allowing the blood to follow the pressure gradient) (example- the deep branch of the transverse cervical artery [dorsal scapular] normally anastomoses with the circumflex branch of the subscapular artery). Important to allow alternate routes of blood flow to tissues. End Artery- An artery that supplies blood to a defined region (organ or muscle) and lacks collateral connections with adjacent arteries (example- a segmental artery of the kidney supplies a distinct vascular segment of the kidney and has no collateral connections with adjacent segmental arteries). Significant because there are no alternate routes of blood to the tissue flow once in an end artery.

4. Describe the blood supply of the upper extremity including the arterial anastomoses associated with the shoulder, elbow and palm. 5. Describe the blood supply of the lower extremity including the arterial anastomoses associated with the hip and knee. 6. Describe the general pattern of lymphatic drainage of the upper and lower extremities including the major groups of lymph nodes. Lymph node regions in the body

(UpToDate.com)

__Early Embryology- I & II__ 1. //Define the following terms, and discuss how they relate to objectives 2 - 6: oocyte// //sperm// //fertilization// //cleavage// //morula// //blastocyst// //blastocele// //inner cell mass// //trophoblast// //implantation// //hypoblast// //epiblast// //amniotic cavity// //yolk sac (primary and secondary)// //germ layers// //gastrulation//

- 5 - //primitive streak, node and pit// //buccopharyngeal membrane// //notochord// //cloacal membrane// //paraxial mesoderm// //intermediate mesoderm// //lateral plate mesoderm// //neural plate, groove, fold, tube// //neural crest// //somatic (parietal) mesoderm// //splanchnic (visceral) mesoderm// //intraembryonic cavity// //head fold, tail fold,// //lateral body folds// //foregut// //midgut// //hindgut// //vitelline duct// //allantois// //cardiogenic field// 2. //Describe the general sequence of developmental stages from fertilization through the end of the fourth week (body folding) and how the developmental stages relate to anatomical sites in the female reproductive tract.// 3. //Describe the general cell movements of gastrulation and the formation of the three germ layers.// 4. In general terms, discuss the ectodermal, mesodermal and endodermal derivatives present in the adult. - “The **ectodermal germ layer** gives rise to the organs and structures that maintain contact with the outside world: (a) **central nervous system** ; (b) **peripheral nervous system** ; (c) **sensory epithelium of ear, nose, and eye** ; (d) **skin, including hair and nails** ; and (e) **pituitary, mammary**, and **sweat glands** and **enamel** of the teeth.” (Langman’s 9th Ed. pp. 112) - The mesoderm germ layer develops to form muscle, skeleton, dermis, urogenital tract, circulatory system, blood and heart. (From slides) - “The **endodermal germ layer** provides the epithelial lining of the **gastrointestinal tract, respiratory tract,** and **urinary bladder**. It also forms the **parenchyma** of the **thyroid, parathyroids, liver**, and **pancreas**. Finally, the epithelial lining of the **tympanic cavity** and **auditory tube** originate the endodermal layer.” (Langman’s pp. 112-114)

From slides: Ectoderm: • Epidermal epithelium, hair, nails, tooth enamel • Nervous system (CNS and PNS) • Neural crest derivatives: pigment cells, tooth dentine, PNS etc. Mesoderm: • Muscle • Skeleton • Connective tissue • Urogenital tract and germ cells • Heart, blood and blood vessels Endoderm: • Gastrointestinal tract epithelium • Respiratory tract epithelium • Endocrine glands

5. //Discuss how the named embryonic axes translate into the named adult axes.// //Anteroposterior → Horizontal (transverse)- divides the body into upper and lower parts (Anterior → Superior, Posterior → Inferior)// //Dorsoventral, → Coronal (frontal)- divides the body into front and back parts (Dorsal → Posterior, Ventral → Anterior)// //left-right → Median- divides the body into right and left halves (sagittal is parallel to median)//

6. //In general terms, discuss how the embryonic disc folds to generate a three-dimensional body and how the cavities after folding relate to the trilaminar disc.//

__Tissues and Systems- VI - X (Nervous)__ 1. Define, compare and contrast the following sets of terms: central nervous system / peripheral nervous system; sensory / motor; and somatic nervous system / visceral (autonomic) nervous system. - The central nervous system (**CNS** ) is comprised of the brain and the spinal cord. The peripheral nervous system (**PNS** ) is comprised of roots, spinal nerves, rami of spinal nerves, peripheral nerves and ganglia. A ganglion is a collection of neuronal cell bodies outside the CNS. - **Sensory** (afferent) neurons convey information (action potentials) towards the CNS. -The **somatic** nervous system innervates bones, joints, skeletal muscles and the body surface. The **visceral** nervous system innervates organs, glands and vessels containing smooth and/or cardiac muscle. Motor systems have anatomically distinct sets of neurons innervating somatic and visceral structures. Sensory systems have overlap in the innervation of somatic and visceral structures. Somatic sensory innervation is well localized, whereas visceral sensory innervation is poorly localized.
 * Motor** (efferent) neurons convey information (action potentials) away from the CNS.

2. Describe the basic structure, function and location(s) of lower motor neurons and primary sensory neurons. -Lower motor neurons are the final common cellular pathway for transmitting nervous system information from many CNS structures to skeletal muscle (efferent). As a one neuron chain, the cell body resides in the ventral horn of the spinal column, the axons exit through the ventral root to the spinal nerve and out to the somatic muscles. Primary sensory neurons are the cells that convey sensory (afferent) information from the periphery to the CNS. As a one neuron chain, the axon resides in the dorsal horn of the spinal cord, leaving through the dorsal root to a dorsal root ganglion, where the cell body resides, the axon leaves through the spinal nerve with the axon terminal receiving sensory information in some part of the body.

3. Describe the basic functions and anatomical locations of astrocytes, oligodendrocytes, microglia and Schwann cells. - Glia (astrocytes [CNS], oligodentrocytes [myelin forming cells in CNS], microglia [CNS] and Schwann cells [myelin forming cells in PNS]) are the “supportive cells” of the nervous system

4. Describe the anatomical relationships between the following set of structures: vertebral column, epidural space; dura mater; arachnoid mater; subarachnoid space; pia mater and spinal cord. 5. Discuss the general functions of the spinal cord.

- 6 - 6. Describe the basic cross-sectional anatomy of the spinal cord and the associated spinal nerves. 7. Describe the segmental organization of the spinal cord and spinal nerves. Discuss the relationship between spinal cord segmental levels and the corresponding levels of the vertebral column. 8. Define the following terms: gray matter; white matter; and neuropil. 9. Describe the structural organization and function(s) of the components of a peripheral nerve. 10. Define, compare and contrast the following terms as they apply to the nervous system: dermatome; sensory cutaneous field; and myotome. 11. Describe the segmental innervation (or specific embryonic origin) of the following muscles of the extremities: rhomboids, serratus anterior; deltoid; supraspinatus; infraspinatus; teres minor; biceps brachii; triceps; muscles of the hand; quadraceps femoris; gastrocnemius; and soleus. 12. Describe (draw) the brachial plexus. 13. Describe (draw) the lumbar and sacral plexuses. 14. Describe the distal sites of innervation (termination) and function of the axons present in the roots, rami and nerves of the peripheral nervous system (use the practice questions for guidance with this objective). 15. Describe the organization of the autonomic nervous system. 16. Compare and contrast the structure and function of the divisions of the autonomic nervous system.

__Introduction to Imaging- I & II__ 1. Describe the imaging modalities currently available for clinical diagnosis. Discuss the terminology needed to properly review the results of each type of imaging study. 2. Discuss the basic tissue properties that are measured and that provide diagnostic information in imaging studies. Describe how pathology presents on an image and why specific imaging studies are ordered. 3. Describe the basic concepts and typical values related to image quality for each type of diagnostic imaging study. Discuss quality standards and the limits of imaging studies. 4. Describe the most common bioeffects and dose characteristics of each type of diagnostic imaging study. Discuss the framework for relating the “cost” of a study to its diagnostic benefit.

__Introduction to the Anatomy Lab- I & II__ 1. Review and discuss student conduct in the dissection lab. 2. Demonstrate professional behavior by treating the cadavers and anatomical specimens with respect, dignity and the appropriate decorum. 3. Review and discuss the dissection lab safety rules. 4. Review and discuss the procedures for the dissection exercises. 5. Demonstrate professional behavior by being punctual and well prepared to participate fully in all scheduled dissection laboratories.

- 7 - 6. Communicate effectively with fellow students while teaching the content of dissection exercises. 7. Review and discuss dissection equipment and basic dissection technique.

__Regional Anatomy- Back__ 1. Discuss the general functions of the vertebral column (spine). 2. Describe the basic differences between cervical, thoracic and lumbar vertebrae. 3. Describe the general attachments and primary functions of the ligaments supporting the vertebral column (spine). 4. Describe the primary and secondary curvatures of the spine. 5. Describe the synovial classification and movements occurring at the joints of the back. 6. Compare and contrast the orientation of the zygapophysial joints at cervical, thoracic and lumbar levels of the vertebral column. At a basic level, describe how the orientation of the joint limits the range of motion of the vertebral column. 7. Describe the basic structure of an intervertebral disc. 8. Describe the relationships between the intervertebral foramen, roots of a spinal nerve and the intervertebral disc. 9. Describe the fascial (thoracolumbar) compartmentalization of the back. 10. Compare the muscles contributing to the stabilization and movement of the vertebral column in terms of location and function.

__Regional Anatomy- Lower Extremity I, II & III__ 1. Discuss the functions of the lower extremity. 2. Describe the compartmental organization of the lower extremity. Describe the primary attachments (as listed under muscles) and actions of the muscles located in each compartment. Describe the innervation and major arterial supply associated with each compartment. 3. Describe the synovial classification and movements occurring at the joints of the lower extremity. 4. Define and differentiate between genu valgus and genu varus. 5. Describe the major ligaments (iliofemoral, pubofemoral, ischiofemoral, medial and lateral collaterals of the knee, anterior and posterior cruciates of the knee, deltoid and lateral ligaments of the ankle) of the lower extremity in terms of movement constraints. 6. Explain the basic components of the gait cycle.

__Embryology of the Vertebral Column and Extremities__ 1. Describe the segmentation of paraxial mesoderm into somitomeres and somites, how the somites rearrange to generate the vertebrae and intervertebral discs, and how segmentation of the somites imposes a segmental arrangement on the spinal nerves. -“By the beginning of the third week, paraxial mesoderm is organized into segments. These segments, known as **somitomeres**, first appear in the cephalic region of the embryo, and their formation proceeds cephalocaudally. Each somitomere consists of mesodermal cells arranged in concentric whorls around the center of the unit.”… “From the occipital region caudally, somitomeres further organize into somites (Somites are epithelial balls surrounding a mesenchymal core, and enveloped in a basal lamina.). The first pair of somites arises in the occipital region of the embryo at approximately the 20th day of development. From here, new somites appear in craiocaudal sequence at a rate of three pairs per day until, at the end of the fifth week, 42 to 44 pairs are present. There are four occipital eight cervical 12 thoracic, five lumbar, five sacral, and eight to 10 coccygeal pairs. The first occipital and the last five to seven coccygeal somites later disappear, while the remaining somites form the axial skeleton.” (pp. 95-97) Somites are transient structures that quickly split into dermotome, sclerotome, and myotome. The ventro-medial cells (the cells closest to the notochord) become sclerotome while the remaining cells become dermomyotome. Sclerotome cells take on a mesenchymal character, and migrate to surround the neural tube and notochord. They will rearrange themselves into the precursors of vertebral bodies and ribs, differentiating into chondrocytes and generating a cartilagenous skeleton. Ossification then transforms cartilage to bone. By the end of the 4th week, motor neurons begin to extend axons, which exit the neural tube, seeking muscles to innervate. These axons grow through the sclerotome that is enveloping the neural tube and contact adjacent myotome. Molecular cues in the rostral half of each somite are attractive to axons. Thus motor axons that exit continuously along the length of the neural tube bundle into spinal nerves as they cross the sclerotome. Similar cues induce migrating neural crest cells to condense into segmented clusters, the dorsal root ganglia. Their processes join the motor axons through the sclerotome, but then accompany the dermotome as it migrates, ultimately leading to the segmented sensory innervation of the skin. Thus the segmental organization of the somites imposes segmental organization on both the spinal nerves and the blood vessels. “During the fourth week of development, cells of the sclerotomes shift their position to surround both the spinal cord and the notochord. This mesenchymal column retains traces of its segmental origin, as the scleratomic blocks are separated by less dense areas containing **intersegmental arteries**. During further development the caudal portion of each sclerotome segment proliferates extensively and condenses. This proliferation is so extensive that it proceeds into the subjacent intersegmental tissue and binds the caudal half of one sclerotome to the cephalic half of the subjacent sclerotome. Hence, by incorporation of the intersegmental tissue into the **precartilaginous vertebral body**, the body of the vertebra becomes intersegmental.” (pp. 193-194) “Mesenchymal cells between cephalic and caudal parts of the original sclerotome segment do not proliferate but fill the space between two precartilaginous vertebral bodies. In the way they contribute to formation of the **intervertebral disc**. Although the notochord regresses entirely in the region of vertebral bodies, it persists and enlarges in the region of the intervertebral disc. Here is contributes to the **nucleus pulposus**, which is later surrounded by circular fibers of the **annulus fibrosus**. Combined, these two structures form the **intervertebral disc** .” (p. 194) “Rearrangement of sclerotomes into definitive vertebrae causes the myotomes to bridge the intervertebral discs and this alteration gives them the capacity to move the spine. For the same reason, intersegmental arteries, at first lying between the sclerotomes now pass midway over the vertebral bodies. Spinal nerves, however, come to lie near the intervertebral discs and leave the vertebral column through the intervertebral foramina.” (p. 194)

2. Diagram the division of somites into sclerotome, dermatome, and myotome. Describe the fates of the sclerotome, dermatome, and myotome. (Langman’s Medical Embryology) ( Langman’s Medical Embryology)

Sclerotome → Organizes and rearranges to produce the vertebral column. Myotome → Musculature. The ends of the DM migrate underneath. The medial cells becoming the axial muscles. The lateral cells becoming body wall muscles, including the flexors of the spine, the intercostal and abdominal muscles, and the limb muscles. Dermatome → The superficial layer is the dermatome, which ultimately migrates under the dorsal ectoderm to become the dermal layer of the skin.

3. Discuss the steps by which muscle and skeletal elements are laid down in the developing limb. -The forelimbs originate on day 24 as bulges on the lateral body wall at the level of C5-C8. The hindlimbs appear by day 25 as bulges at the level of L3-L5. Between the 5th and 8th weeks, they develop to essentially the mature morphology. First, lateral plate mesoderm proliferates and bulges out of the lateral flank at the appropriate positions along the rostral-caudal axis. As the limb grows, the internal mesenchyme begins to coalesce into shapes that predict shape and position of the bones. The condensations form in proximal to distal sequence. The condensations form as a continuous unit. Individual elements form by branching and by joint formation. As the condensations reach a high enough cell density, they begin to differentiate into chondrocytes. Through the process of endochondrial ossification, they differentiate into cartilage and then bone. Apoptosis contributes to modeling the limb mesenchyme. There are 4 major sites of apoptosis in the limb. Anterior and posterior zones in the upper limb, an interior zone in the lower limb (e.g. between radius and ulna), and the interdigital zones that form the spaces between the digits. Apoptosis also contributes to formation of the synovial joints. The humerus and the digits are the same size when the mesenchyme condensations form. It is differential growth that makes them ultimately so different in size. Muscle precursors, derived from myotomes (hypomere) of several somites, enter the limb shortly after the skeletal elements begin to condense. The muscle precursosr already have nerves associated when they invade the limb. The mesenchyme condensations force the muscle precursors into either a dorsal path (where they will ultimately become the extensors) or a ventral path (where they will ultimately become the flexors). Thus the segmental bundles of spinal nerves are split into dorsal and ventral branches as they enter the limb. Ventral branches of the intersegmental arteries are associated with the hypomere cells as they enter the limb. Most branches regress, and a single intersegmental artery takes over the blood supply for the limb. In the forelimb the 7th cervical intersegmental artery takes over. It becomes the subclavian artery in the thoracic cavity and continues into the limb as the brachial, and anterior interosseous arteries and the deep palmar arch. In the hindlimb, the 5th lumbar artery takes over, becoming the common iliac artery and its more distal branches. As the limb matures, the dorsal and ventral branches of each spinal nerve coalesce around the limb artery before they enter the limb, forming the brachial and lumbosacral pelxae. The nerves preserve their dorsoventral and rostrocaudal organization, emerging as the musculocutaneous, the ulnar (post axial, C8-T2), and median (preaxial, C5-C7) nerves of the ventral compartment, and as the axialary and radial nerves of the dorsal compartment.

“The first indication of limb musculature is observed in the seventh week of development as a condensation of mesenchyme near the base of the limb buds. The mesenchyme is derived from dorsolateratal cells of the somites that migrate into the limb bud to form the muscles. As is other regions, connective tissue dictate the pattern of muscle formation, and this tissue is derived from somatic mesoderm, which also gives rise to the bones of the limb.” (pp. 203-204)

4. In general terms, discuss the growth of the skeletal elements and formation of the joints. -“While the external shape is being established, mesenchyme in the buds begins to condense and these cells differentiate into chondrocytes. By the 6th week of development the first **hyaline cartilage models**, foreshadowing the bones of the extremities, are formed by these chondrocytes. Joints are formed in the cartilaginous condensations when chondrogenesis is arrested and a joint **interzone** is induced. Cells in this region increase in number and density and then a joint cavity is formed by cell death. Surrounding cells differentiate into a joint capsule.” (p. 183) “Ossification of the bones of the extremities, **endochondral ossification**, begins by the end of the embryonic period. Primary **ossification centers** are present in all long bones of the the limbs by the 12th week of development. From the primary center in the shaft or **diaphysis** of the bone, endochondral ossification gradually progresses toward the ends of the cartilaginous model. At birth the diaphysis of the bone is usually completely ossified, but he two ends, the **epiphyses**, are still cartilaginous. Shortly thereafter, however, ossification centers arise in the epiphyses. Temporarily a cartilage plate remains between the diphyseal and epiphyseal ossification centers. This plate, the **epiphyseal plate**, plays an important role in the growth in the length of the bones. … In long bones an epiphyseal plate is found on each extremity; in smaller bones, such as the phalanges, it is found only at one extremity; and in irregular bones, such as the vertebrae, one or more primary centers of ossification and usually several secondary centers are present.” (pp. 184-185)

5. Describe the rotation of the upper and lower extremities during limb development. -During the 7th week the limbs rotate in opposite directions. The forelimbs rotate 90o laterally so that the extensors lie posteriorly and the thumbs lie laterally. The hindlimbs rotate 90o medially so that the extensors lie anteriorly and the big toes lie medially.

- 8 - __Regional Anatomy- Upper Extremity I, II & III__ 1. Discuss the functions of the upper extremity. 2. Describe the compartmental organization of the upper extremity. Describe the primary actions of the muscles located in each compartment. Describe the innervation and major arterial supply associated with each compartment. 3. Describe the synovial classification and movements occurring at the joints of the upper extremity. 4. Discuss the structure and function of the dorsal digital expansions.

__Unit I Clinical Anatomy- I & II__ Refer to this specific Blackboard session for the learning objectives.


 * Small Group Sessions**

__The Cadaver as Your First Patient__ 1. Identify the values involved in treating the cadaver as your "first patient." 2. Describe the role of culture in attitudes towards death and the use of cadavers. 3. Describe experiences with human dissection in the form of a narrative. 4. Share perspectives on the experience of human dissection with colleagues. 5. Identify the role of colleagues in providing support.

__Problem Based Learning Case 1__ Objectives for the PBL cases are not released until the end of the case.