(answer b)supplies the flexor carpi ulnaris and a portion of flexor digitorum
profundus. The axillary nerve (answer d)innervates the deltoid and teres
minor and is thus involved in abduction of the arm. The musculocutaneous
nerve (answer e)innervates flexors of the elbow joint (e.g., biceps brachii).
472.The answer is b.(Moore and Dalley, pp 621–622.)The boy has lost
partial function of the gluteus medius muscle causing hip drop on the
opposite side, which is called a “positive Trendelenburg sign.” The gluteus
medius (thus not answer c) is innervated by the superior gluteal nerve.
The nurse who performed the injections likely injected too far medial
within the buttock. Normally all injections should be performed in the
upper lateral quadrant of the buttock, to stay away from the sciatic nerve
and superior and inferior gluteal nerves that exit the pelvis through the
greater sciatic notch. The lateral cutaneous nerve of the thigh (answer a)
would provide general sensation to the anterior region of the thigh. The
superior clunial nerves supple the skin over the gluteus maximus and
medius muscles. The inferior gluteal nerve (answer d)innervates the glu-
teus maximus muscle. The sciatic nerve (answer e)isnotdamaged because
the pain does notextend down the back of the boy’s leg and he has normal
function of his hamstring muscles, which flex the leg at the knee.
473.The answer is b.(Moore and Dalley, pp 21, 831–832, 867, 879.)The
flexor pollicis brevis has two heads and there is a sesamoid bone associated
with each of the tendons of these heads. Sesamoid bones are isolated islands
of bone that may occur in tendons passing over joints. The patella is the
classic example. The adductor pollicis (answer c)also has two heads (trans-
verse and oblique), but they are notassociated with sesamoid bones.
[(Answers a, d, and e)are not correct.]
474.The answer is d.(Moore and Dalley, pp 745–747.)The ulnar nerve
descends along the postaxial (ulnar) side of the forearm. It passes lateral to
the pisiform bone and under the carpal volar ligament, but superficial to the
transverse carpal ligament. In the hand it divides into superficial and deep
branches. The median nerve (answer a)lies deep to the transverse carpal lig-
ament where it is protected from superficial lacerations. Emerging from the
carpal tunnel, it gives off the vulnerable recurrent branch (answer b)to the
thenar eminence. The superficial branch of the radial nerve (answer c)sup-
plies the dorsolateral aspects of the wrist and hand.
Extremities and Spine Answers 595