Question

Muscles of the posterior compartment of the forearm ________ the wrist and are innervated by the _________nerve.

A. extend, radial

B. flex, radial

C. flex, ulnar

D. flex, radial

A man was in a car accident and severed his ulnar nerve. Will he still be able to abduct and adduct his lateral four digits?

A. Yes, because there are still two lumbricals that are not innervated by ulnar nerve

B. Yes, because the lumbricals are not innervated by the ulnar nerve

C. No, because the lumbricals are innervated by the ulnar nerve

D. No, because the ventral and dorsal interosseous muscles are innervated by the ulnar nerve

E. Yes, because the ventral and dorsal interosseous muscles are not innerved by the ulnar nerve

Answer 1

1. Muscles of the posterior compartment of the forearm extend the wrist and are innervated by the radial nerve (option A).

Posterior compartment of forearm consists of seven superficial muscles and five deep muscles, all are innervated by radial nerve especially the deeper branch.

2. No, because the ventral and dorsal interosseous muscles are innervated by ulnar nerve (option D).

Ventral and dorsal interossei are responsible for adduction and abduction of the fingers respectively and they both are supplied by the deep branch of ulnar nerve.

So, when the ulnar nerve is severed, the person will not be able to adduct or abduct his lateral four digits.