Study questions Anatomy

Supination of the hand and forearm would be diminished by loss of radial nerve function. But one very powerful supinator would remain intact and unaffected, namely: Brachialis Brachioradialis Biceps brachii Flexor carpi radialis Supinator

Biceps brachii supinates the arm, but it is not innervated by the radial nerve--instead, it is innervated by the musculocutaneous nerve. So, it would not be affected by a radial nerve injury. Brachialis is also innervated by the musculocutaneous nerve, but it is only involved with flexing the forearm--it is not a supinator. Brachioradialis flexes the elbow and assists in pronation and supination--it is innervated by the radial nerve and would be paralyzed after a radial nerve injury. Flexor carpi radialis is a flexor, not a supinator--it is innervated by the median nerve. Finally, supinator is innervated by the deep radial nerve.

Interruption of the median nerve in the cubital fossa affects what movement(s) of the thumb? Flexion Opposition Both Neither

Both The recurrent branch of the median nerve innervates the thenar compartment of the hand. This nerve innervates opponens pollicis, which opposes the thumb, and flexor pollicis brevis, which helps to flex the thumb. So, disrupting the median nerve would impair both flexion and opposition of the thumb.

What muscle is innervated by branches of both the median and ulnar nerves? Flexor carpi ulnaris Flexor digitorum profundus Flexor digitorum superficialis Flexor pollicis longus Pronator quadratus

Flexor digitorum profundus The median and ulnar nerve both innervate flexor digitorum profundus. Flexor carpi ulnaris is innervated by the ulnar nerve only. Flexor digitorum superficialis and flexor pollicis longus are innervated by the median nerve. Pronator quadratus is innervated by the anterior interosseus nerve, which is a branch of the median nerve.

The anterior interosseous is a branch of which nerve?

Median

The tendons on the dorsal side of the wrist are held in place by a thickening of the antebrachial fascia called the:

extensor retinaculum

Structures within the carpal tunnel include the: Radial bursa Ulnar bursa Both Neither

BOTH The radial bursa and ulnar bursa are both found in the carpal tunnel. These bursae are complex synovial coverings that protect the flexor tendons. The carpal tunnel is formed where the flexor retinaculum spans from the scaphoid and trapezium to the hamate and pisiform, deep and slightly distal to the palmar carpal ligament. This creates a canal that covers the flexor digitorum superficialis tendons, the flexor digitorum profundus tendons, the tendon of flexor pollicis longus, and the median nerve. These tendons in the carpal tunnel are covered by the ulnar and radial bursae. The flexor digitorum superficialis and flexor digitorum profundus tendons are covered by the ulnar bursa, and the tendon of flexor pollicis longus is covered by the radial bursa. So, both bursae are in the carpal tunnel.

A middle-aged woman comes to you complaining of pain on the lateral side of her right elbow, so severe that she holds her eating utensils in her left hand to eat. She says that she spent the weekend putting in a new garden plot and that it involved loosening and turning over a large area of grass sods with a garden fork. You find that the region just proximal to the lateral epicondyle of her humerus is painful to the touch. There is no sensory loss in her forearm or hand. You suspect a localized tearing of the origin of a muscle producing the equivalent of "tennis elbow." The muscle most likely involved is the: brachioradialis common flexor tendon extensor carpi radialis brevis extensor digitorum pronator teres

Brachioradialis Tennis elbow is usually caused by inflammation of the common extensor tendon on the lateral side of the forearm, but we know that that's not what happened here. Instead, the patient tore a muscle at its origin, near the lateral epicondyle of the humerus. Brachioradialis originates from the upper two-thirds of the lateral supracondylar ridge of the humerus, so this is the muscle that she probably tore. This also makes sense given her activities--brachioradialis flexes the elbow and assists in pronation and supination, so she would have been using this muscle while gardening. The common flexor tendon is associated with the medial epicondyle, not the lateral epicondyle. Extensor carpi radialis brevis and extensor digitorum take origin from the common extensor tendon, which attaches to the lateral epicondyle. This tendon would be inflamed in a classic case of tennis elbow, but the common extensor tendon is not the structure that was injured in this patient's case. Pronator teres takes origin from the common flexor tendon and the medial side of the ulna.

If the tendon of palmaris longus were transected, what movement would be affected? Flexion of the MP and IP joints of the thumb Flexion of the proximal IP joints of digits 2 and 5 Flexion of the proximal IP joints of digits 3 and 4 Flexion of the wrist Extension of the wrist

Flexion of the wrist Palmaris longus is a small muscle in the anterior compartment of the arm--it flexes the hand at the wrist and tightens the palmar aponeurosis. If this tendon was cut, it would be more difficult to flex the wrist. Flexor pollicis longus flexes the MP and IP joints of the thumb. Flexor digitorum profundus and superficialis flex the proximal IP joints of digits 2, 3, 4, and 5. Extensor carpi ulnaris, extensor carpi radialis longus and extensor carpi radialis brevis all extend the wrist.

Compression of the median nerve in the carpal tunnel affects which hand muscle(s)? Dorsal interossei Flexor pollicis brevis Flexor pollicis longus Opponens digiti minimi Palmar interossei

Flexor pollicis brevis The recurrent branch of the median nerve innervates the thenar compartment of the hand, including flexor pollicis brevis, abductor pollicis brevis, and opponens pollicis. So, if the median nerve was compressed, all of these muscles might be affected. The dorsal interossei, palmar interossei, and opponens digiti minimi are all muscles of the hand which are innervated by the deep branch of the ulnar nerve. Flexor pollicis longus is innervated by the median nerve, but it is a forearm muscle which is proximal to the carpal tunnel. Therefore, it would not be affected by compressing the median nerve in the carpal tunnel.

A worker doing repetitive lifting develops an inflammation in the tendon of origin of the extensor carpi radialis brevis muscle, commonly called "tennis elbow". The focal point of pain would most likely be near which palpable bony landmark? Coronoid process of ulna Lateral epicondyle of humerus Lateral supracondylar ridge of humerus Medial epicondyle of humerus Medial supracondylar ridge of humerus Olecranon Posterior (subcutaneous) border of ulna

The correct answer is: lateral epicondyle of the humerus The extensor carpi radialis brevis muscle originates from the common extensor tendon off the lateral epicondyle of the humerus. So, an injury to this tendon would result in pain near the lateral epicondyle. Tennis elbow is due to the repetitive use of superficial extensor muscles of the forearm--the pain is often felt at the lateral epicondyle and it radiates down the posterior surface of the forearm. None of the other bony landmarks are associated with the common extensor tendon, although the medial epicondyle is the origin of the common flexor tendon.

The victim of multiple shrapnel wounds to the upper limb must have his forearm amputated at midlength. Because of concomitant damage in the patient's arm, the surgeon must ligate the main artery at some point. The best chance of saving collateral circulation to the stump of the forearm would be when the ligature is placed just below which of the following? Beginning of brachial artery Origin of the deep brachial artery Origin of the superior ulnar collateral artery Origin of the inferior ulnar collateral artery Bifurcation of the brachial artery

bifurcation of the brachial artery The brachial artery bifurcates near the elbow. It forms two branches that become the radial and ulnar arteries. If these arteries were ligated after this bifurcation, there would be a chance at saving collateral circulation to the forearm because the ulnar artery might have already given off its common interosseous branch, which could carry blood to the forearm through the anterior and posterior interosseus arteries. Ligating near the beginning of the brachial artery would stop blood from flowing through the rest of the upper limb. Ligating near the origin of the deep artery, by the origin of the superior ulnar collateral artery, or near the origin of the inferior ulnar collateral artery might preserve enough collateral circulation to supply the elbow. However, there would not be collateral circulation to the forearm. For a better picture of these arterial connections, see Netter Plate 434.

While going up for a rebound, a basketball player jams her middle finger against the ball. She experiences severe pain and the trainer notes that she can no longer extend the distal phalanx of the finger. The injury has avulsed (torn away from the bone) which structure from her distal phalanx to produce this condition? extensor carpi radialis brevis tendon extensor carpi radialis longus tendon extensor digiti minimi tendon extensor expansion extensor indicis tendon

extensor expansion

The victim of multiple shrapnel wounds to the upper limb must have his forearm amputated at midlength. Because of concomitant damage in the patient's arm, the surgeon must ligate the main artery at some point. The best chance of saving collateral circulation to the stump of the forearm would be when the ligature is placed just below which of the following? Lateral antebrachial cutaneous Medial antebrachial cutaneous Median Radial Ulnar

median nerve The median nerve provides sensory innervation to the skin of the radial 3.5 fingers of the palm. So, the patient's loss of cutaneous sensation is suggestive of a median nerve injury. The location of the injury also implies that there has been an injury to the median nerve--this nerve enters the hand by crossing under the flexor retinaculum on the anterior side of the wrist. The lateral and medial antebrachial cutaneous nerves provide cutaneous innervation to the anterior side of the forearm--the symptoms here are not consistent with an injury to these nerves. The radial nerve innervates the radial side of the dorsum of the hand but does not innervate the palmar side of the hand. The ulnar nerve innervates the medial (ulnar) side of both the dorsum and palm of the hand.

A patient is severely limited in extension at the wrist joint after several months in a cast following a Colles fracture. Which joint would be especially important in therapy to regain full extension?

radiocarpal The radiocarpal joint is the joint commonly known as the wrist joint--it is a condyloid (oval) type of synovial joint that allows for flexion and extension, abduction and adduction, and circumduction. A Colles fracture is a fracture of the distal end of the radius--this is why this sort of break would limit movement between the radius and carpals. The carpometacarpal joint is found between the distal row of carpals and the metacarpals--these joints are mobile for the thumb and little finger, allowing extension, flexion, abduction, and adduction. However, the carpometacarpal joints are quite immobile for the middle three fingers. The distal radioulnar joint is located between the distal ends of the radius and ulna--this joint allows the radius and ulna to rotate around each other during pronation and supination. The midcarpal joint is located between the proximal and distal row of carpals--this joint is important for flexion and extension of the hand. As for the "ulnocarpal joint," the ulna does not articulate with the carpal bones--it articulates with the distal end of the radius only.