Lab clinical correlations

Question 1

A patient presents with the stab wound of the right lateral thorax. The injury resulted in a complete laceration of a nerve that supplies an important scapular muscle in the area. Name the nerve affected. What physical symptom would the patient present with? What actions would be compromised due to the laceration? What other motor and/or sensory deficits might occur as a consequence of this injury?

Answer 1

The long thoracic nerve, paralysis of the serratus anterior muscle

• Physical sx present would be the movement of the medial border of the scapula laterally and posteriorly away from the thoracic wall, giving he scapula the appearance of a wing, especially when a person leans on a hand or presses the upper limb against a wall.
• Actions compromised would be limited abduction of the upper limb beyond 90 degrees, as the serratus anterior is unable to rotate the glenoid cavity superiorly to allow complete abduction of the limb

Question 2

The ossification of the superior transverse scapular ligament could compress the structure running beneath it. Name the structure and potential deficits that a patient with this condition might experience.

Answer 2

• Suprascapular nerve
• Innervates the supraspinatus and infraspinatus muscles
• Deficits may include weakened initiation of abduction of the upper limb and significantly weakened lateral rotation since the infraspinatus is responsible for about 90% of lateral rotation.

Question 3

A physician notices that a paitient is unable to “shrug” their left shoulder. Which nerve is most likely injured? Which muscle is responsible for the presenting symptom?

Answer 3

The spinal accessory nerve

• The trapezius muscle
• The superior fibers are responsible for a portion of shoulder elevation and so an injury to the spinal accessory nerve on the L side would remove the ability of the trapezius to elevate the shoulder on the L side.

Question 4

An elderly man falls while riding his bike and lands on his right outstretched arm resulting in a fracture of the surgical neck of the humerus. Which neurovascular structures are most likely to be affected by this injury? What signs and symptoms should you look for to assess whether these structures are intact?

Answer 4

Neurovascular structures at the most risk in this injury are the axillary nerve
- Since the axillary nerve innervates the deltoid, testing the deltoid would be a good way to assess the damage to the nerve. If the nerve is injured, the pt may have weakned abduction of the upper limb, weakened flexion, medial rotation, extension and lateral rotation. Depending on the duration of the injury, muscle atrophy of the deltoid may be present producing a flattened appearance with a hollow inferior to the acromion. There would be loss of sensation to the lateral proximal aspect of the arm due to the impacted superior lateral cutaneous nerve of the arm.

Question 5

After being diagnosed with cancer a woman undergoes a mastectomy of the left breast. As she was recovering from surgery she notes difficulty reaching behind her back to touch between her shoulder blades with her left arm. What nerve was likely lacerated during the surgery and what muscle(s) is (are) affected?

Answer 5

The thoracodorsal nerve innervating the latissimus dorsi-responsible for extension, adduction and medial rotation of the arm.
This nerve is vulnerable to injury during mastectomies when the axillary tail of the breast is removed.

Question 6

A patient presents to the ER after being thrown from a horse. The patient has injured C5 and C6 spinal nerves. What position/posture would the limb adpot? Describe and explain

Answer 6

Injuries to the superior portion of the brachial plexus occur from excessive increase in the angle between the neck and the 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 the shoulder. When thrown , the person’s shoulder often hits something ( a tree or the ground) and stops while the head and the trunk continue to move. This stretches or ruptures the superior parts of the brachial plexus or avulses (tears) the roots of the plexus from the spinal cord.
Apparent by a characteristic position of the upper limb as waiter’s tip position-in which the limb hangs by the side in medial rotation
As a result of the paralysis to the muscles of the shoulder and arm supplied by the C5 and C6 spinal nerves, paralysis of the muscles occurs-deltoid, biceps and brachialis
- upper limb with an adducted shoulder, medially rotted arm ad extended elbow.

Question 7

Upon fracture of the clavicle, patients often are seen with a medially rotated arm. What is responsible for this rotation? What complications could this lead to?

Answer 7

After the fx of a clavicle, the sternocleidomastoid muscle elevates the medial fragment of the bone, and b/c the subcutaneous position of the clavicle, the end of the superiorly directed fragment is prominent-the trapezius is unable to hold the lateral fragment up owing to the weight of the upper limb and thus the shoulder drops. People with fx clavicles support the sagging limb with the other limb and 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 pec major. Overriding of the bone fragments causes the shortening of the clavicle. This could cause injury to any underlying arteries, veins or nerves in the immediate area and subsequent effects to the structures which those structures serve.

Question 8

A motorcycle accident injures the superior trunk of an individual’s brachial plexus. The patient struggles to flex the arm, but is able to extend the arm from the flexed position. Explain the role of the pectoralis major muscle in this clinical finding.

Answer 8

acting alone, the pec major at the clavicular head flexes the humerus and sternocostal head extending it from the flexed position. While the superior trunk of the brachial plexus is out and this has removed the ability of the pec major (innervated by C5 and C6) to contribute to flexion of the humerus, but the sternocostal head of the pec major is innervated by the lower branches of C7, C8 and T1 which would still be intact and functional.

Question 9

Shortly after leaving the hospital a new mother realizes her child is unable to extend the fingers of his hand (claw hand). Explain how this might have occurred. What, if any, sensory deficits would you expect? What is the clinical name for this condition?

Answer 9

It is likely that the baby sustained an injury to the inferior part of the brachial plexus called Klumpke paralysis
The baby’s upper limb was likely pulled excessively during delivery injuring the inferior trunk of the brachial plexus (C8 and T1) and may have avulsed the roots of the spinal nerves from the spinal cord. The claw hand results as the short muscles of the hand are affected, creating a claw like appearance.

Question 10

After an awkward golf swing a patient experiences acute lower back pain. Later he also notices that it radiates from his back to his hip and posterior thigh. What type of injury likely occurred? Explain the anatomical features of this injury.

Answer 10

It is likely the pt has sustained a IV disc herniation in the L5-S1 region termed Sciatica.
This herniated disc is compressing and comprising the L5 or S1 component of the sciatic nerve causing referred pain.
Herniations typically occur with hyperflexion and the nucleus pulposus is extended posterolaterally where the anulus fibrosis is thin and there is not direct support from the anterior or posterior longitudinal ligaments.
The localized back pain likely results from the herniated disc pressing on the longitudinal lig and the peripheral of the anulus fibrosis and from local inflammation caused nu chemical irritation by substances from the ruptured nucleus pulpsosus.
Chronic pain results from compression of the spinal nerve roots by the herniated disc which is usually referred pain, perceived as coming from the area (dermatome) supplied by that nerve . Because the IV discs are largest in the lumbar region and lumbosacral regions, were movements are consequently greater, posteriorlateral herniations are most common in these regions.

Question 11

A patient is rear-ended in a car accident, but does not appear to have sustained injuries. The next day however, she experiences intense pain in the neck and scapular region. Explain the mechanism of injury. What anatomical structures might possibly be damages with this injury?

Answer 11

The pt likely has whiplash, caused by severe hyperextension of the head and neck during the rear-end mechanism of the MVC. Tends to occur when the head restraint is placed too low.
The anterior longitudinal ligament is at risk for being severely stretched or torn as this is the only ligament in the vertebral column that resists hyperextension. Can also get a tear drop fx and dislocation of the vertebrae

Question 12

During childbirth caudal epidural anesthesia is often used to help manage pain. Describe the bony landmarks that help guide this procedure, the path of the needle, and the nerves affected by the anesthetic agent.

Answer 12

The sacral hiatus is closed by the sacrococcyeal lig which is pierced by the filum terminale. Deep to the lig, the epidural space of the sacral canal is filled with fatty connective tissue. In caudal epidural anesthesia or caudal analgesia, a local anesthetic agent is injected into the fat of the sacral canal that surrounds the proximal portions of the sacral nerves. This can be accomplished by several routs including the sacral hiatus b/c the sacral hiatus is located between the sacral cornua and inferior to the S4 spinous process or median sacral crest, these palpable bony landmarks are important for locating the hiatus. the anesthetic soln spreads superiorly and extradurally, where it acts on the S2, Co1 spinal nerves of the cauda equina. the height to which the anesthetic ascends is controlled by the amt injected and the position of the pt. Sensation is lost inferior to the epidural block and the anesthetic agents can also be injected through the posterior sacral foramna into the sacral canal around the spinal nerve roots

Question 13

Discuss the neurovascular structures at risk of damage and the clinical features given fractures of the humerus at the following landmarks:
• Surgical neck
• Radial groove
• Distal end
• Medial epicondyle
• Lateral epicondyle

Answer 13

-Surgical neck: axillary nerve, dec/loss of function to the deltoid/teres minor, lat prox sensation of arm affected. Common in the elderly with osteoporosis whose demineralized bones are brittle. Humeral fx often result in one fragment being driven into the spongy bone of the other fragment (impacted fxx) and usually result from a minor fall on the hand with the force being transmitted up the forearm bones of the extended limb. B/c of the impaction of the fragments, the site is sometimes stable and the person is able to move the arm passively with little pain.
An avulsiono fx of the greater tubercle of the humerus is most commonly seen in middle aged and elderly pple. Small part of the tubercle is avulsed and usually results from a fall on the acromion. In younger people, usually results from a fall on the hand when the arm is abducted.
- Radial groove: Radial nerve: Supplies the extensors of the arm and forearm, Also the brachioradialis which is an accessory flexor of the forearm. The function of these muscles would be weakened or lost. Sensation in areas innervated by the radial nerve would be decreased or lost.
- Distal end of the humerus: median nerve, supplies most of the flexors of the forearm and hand, would impact function of these muscles, would impact sensation to associated areas innervated by the median nerve.
-Medial epicondyle: ulnar nerve, supplies some flexor muscles of the forearm, hand, adductors. Sensation. Functions would be dec or lost.

Question 14

During a bar fight, a man is stabbed in the axilla. Forearm flexion and supination have been greatly weakened, but not lost. Sensation to the lateral forearm is lost. What nervous structure(s) is/are like to have been cut? Explain the findings and why he is still able to perform forearm flexion and supination.

Answer 14

The musculocutaneous nerve has like been injured and has resulted in paralysis of the coracobrachialis, the biceps, and brachialis. Weak flexion and supination is still present as other muscles are contributing (brachioradialis and the supinator, both of which are supplied by the radial nerve), but the more powerful muscles involved in flexion and supination of the forearm have been lost. Injury to this nerve would also result in loss of sensation to the lateral forearm supplied by the lateral antebrachial cutaneous nerve, a continuation of the musculocutaneous nerve

Question 15

You suspect a patient has ruptured their long head of the biceps tendon. What would you expect the clinical presentation of this individual to look like?

Answer 15

Rupture of the biceps tendon occurs because of wear and tear of an inflamed tendon as it moves back and forth in the intertuercular sulcus of the humerus. Tendon is tor from its attachment to the supraglenoid tubercle of the scapula and the rupture is often dramatic and associated with a snap or a pop
The detached muscle belly forms as a ball near the center of the distal part of the anterior aspect of the arm (Popeye deformity)

Question 16

A 60 year old, postmenopausal female slipped while walking on ice. She complains of wrist pain and you note that her styloid process of the ulna projects more distally than the styloid process of the radius. Explain why this may be occurring.

Answer 16

It is likely that the pt has sustained a fx of the distal end of the radius which is a common fx in adults >50 years of ge. A complete transverse fx of the distal 2 m of the radius, called a Colles fx, is the most common f of the forearm. The distal fragment is displaced dorsally and is often comminuted (broken into pieces). The fx results from forced extension of the hand, usually as the result of trying to ease a fall by an outstretched hand (FOOSH).
Often the ulnar styloid process is avulsed or broken off. Normally, the radial styloid process projects farther distally than the ulnar styloid, but when a colles fx occurs, the relationship is reversed due to the shortening of the radius. Fx 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.

Question 17

A construction worker complains of pain in the anterior forearm. Pain is exacerbated when screwing boards during a project. What nerve is likely under trauma? Explain the motor and sensory deficits the worker may be experiencing.

Answer 17

It is likely that the worker is suffering from pronator syndrome, a nerve entrapment syndrome that is caused by compression of the median nerve near the elbow near the heads of the pronator teres as a result of trauma, muscular hypertrophy, or fibrous bands. First seen clinically with pain and tenderness in the proximal aspect of the anterior forearm and hypesthesia (decreased sensation)of the palmar aspects of the radial three and half digits and adjacent palm. Sx often follow activities that involve repeated pronation.

Question 18

Describe (using anatomical landmarks) two areas of the wrist/forearm distal to the cubital fossa that can be used clinically to assess pulse rate.

Answer 18

Where the radial artery lies on the surface of the distal end of the radius, lateral to the tendon of the FCR. here the artery is covered by only fascia and skin. Can be compressed against the distal end of the radius where it lies between the tendons of the FCR and the APL. When measuring pulse rate, pulp of the thumb should not be used as the thumb has its own pulse which could obscure the pts own pulse. If a pulse cannot be felt, try the other wrist as an aberrant radial artery on one side may make the pulse difficult to palpate. The radial pulse may also be felt by lightly palpating in the anatomic snuffbox.

Question 19

A patient is cut on the posterior forearm while working at a factory. You are worried about damage to the radial nerve. Explain how do you would differentiate between damag of the deep and superficial branches?

Answer 19

Severance of the deep branch of the radial nerve may occur when wounds of the posterior forearm are deep and penetrating and results in an inability to extend the thumb and metacarpal joints of teh other digits. So the integrity of the deep branch ay be tested by asking the person to extend the MP joints while the examiner proides resistance. If the nerve is intact, the long extensor tendons should apper prominently on the dorsum of the hand, confirming that the extension is occurring at the MP joints rather than at the interphalangeal joints (movements under the control of other nerves). Loss of sensation does not occur b/c the deep brance of the radial nerve is entire muscular and articular in distribution.
When the superficial branch of the radial nerve is injured, a cutaneous nerve is severed and sensory loss is usually minimal. Commonly, a coin shaped area of anesthesia occurs distal to the bases of the 1st and 2nd metacarpals. The reason the area of sensory loss is less than expected is the result of the considerable overlap from cutaneous branches of the median and ulnar nerves.

Question 20

A secretary complains of paresthesia of the lateral digits and difficulty in activities involving fine motor skills. What syndrome is the patient at risk for? Explain all of the structures that may be potentially damaged.

Answer 20

The secretary likely has carpal tunnel syndrome. This syndrome occurs from any lesion that significantly reduces the size of the carpal tunnel or increases the size of the nine sstructures or their coverings that pass through it. Fluid retention, infection and excessive exercise of the fingers may cause swelling of the tendons or teir synovial sheaths. The median nerve is the most sensitive structure in teh tunnel The median nerve has two terminal sensory branches that supply the skinof hte hand; hence paresthesia, hypoesthesia or anesthesia may occur in the lateral 3 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.

Nerve also has one terminal motor brance, the recurrent brance, which serves three thenar muscles
Progressive loss of coordination and strength of 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 opposed their thumbs and have difficulty buttoning a shirt or blouse as well as griping things such as a comb. As the condition progresses, sensory changes radiate into the forearm and axilla and sx of compresson can be reproduced yb compression of the median nerve with finger at the wrist for about 30 seconds.
To relieve both the compression and the resulting sx, 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.

Question 21

A teenage girl fell while skateboarding and landed awkwardly on her hand with her wrist extended and abducted (radial deviation). She experienced pain on the lateral half of the wrist during all wrist movements, but specifically extension and abduction (radial deviation). You gently palpate the wrist and notice her flinch when you palpate near the anatomical snuffbox. What injury is most likely? Describe possible complications that can occur with this type of injury.

Answer 21

She likely has sustained a fx to teh scaphoid, whch often results from a fall on the palm when the hand is abducted. The fx occurs across the narrow part of the scaphoid. Pain occurs primarily on the lateral side f the wrist, especially during dorsiflexion and abduction of the hand. Initial radiographs of the wrist may not reveal a fx; often this injury is misdiagnosed as a severely sprained wrist.
Radiographs taken 10-14 days later reveal a fx b/c bone resorption has occurred there. Owing to the poor blood supply to the proxomal art of the scaphoid, union of the fx parts may take at least 3 months. Avascular necrosis of the proximal fragment of the scaphoid (pathological death of the bone resulting from inadequate blood supply) may occur and produce degenerative joint disease of the wrist. In some cases, t is necessary to fuse the carpals surigcally (arthrodesis)