Which of the following is NOT seen in low radial nerve palsy?
A. Weakness of brachioradialis
B. Loss of nerve supply to extensor pollicis brevis
C. Paralysis of extensor carpi radialis brevis
D. Loss of sensations over first dorsal web space
E. None of the above
Answer. A. (Weakness of
brachioradialis)
• Radial nerve course: It emerges out
from the radial groove and enters the anterior compartment of the arm. Here it
gives muscular branches to brachioradialis and extensor carpi radialis longus.
Then it reaches the anterior aspect of the lateral epicondyle and divides into
two terminal branches:
• PIN (posterior interosseous
nerve)—supplies extensor carpi radialis brevis (ECRB) as well as all the
extensors of the fingers (including thumb).
• Superficial cutaneous branch to the
postero-lateral hand.
• Now, in a lesion of radial nerve
below radial groove, there should be paralysis of Extensor carpi radialis
brevis and finger extensors. There should also be cutaneous loss
on dorsum of the hand. Only option that appears to be the answer is weakness
of brachioradialis. And this will happen only if the nerve was damaged
below the radial groove and above its terminal branches.
