Question

an injury that results in complete functional loss of the ulnar nerve will affect which of the following muscles?

a abductor digitiminimi
b abductor pollicisbrevis
c flexor carpiradialis
d brachioradialis
e extensorindicis

Explanation:

Identify the nerve and its target region

The question asks which muscle is affected by a complete functional loss of the ulnar nerve. The ulnar nerve runs down the medial side of the arm and forearm, passing behind the medial epicondyle of the humerus, and enters the hand. It innervates several muscles in the anterior compartment of the forearm and the majority of the intrinsic muscles of the hand.

Analyze the innervation of each option

• Abductor digiti minimi: This is an intrinsic muscle of the hand located in the hypothenar eminence (acting on the little finger). Intrinsic hand muscles in the hypothenar compartment are innervated by the deep branch of the ulnar nerve.
• Abductor pollicis brevis: This is an intrinsic muscle of the hand located in the thenar eminence (acting on the thumb). It is innervated by the recurrent branch of the median nerve.
• Flexor carpi radialis: This is a superficial muscle of the anterior forearm. It is innervated by the median nerve.
• Brachioradialis: This is a muscle of the posterior/lateral compartment of the forearm. It is innervated by the radial nerve.
• Extensor indicis: This is a deep muscle in the posterior compartment of the forearm. It is innervated by the posterior interosseous nerve, which is a branch of the radial nerve.

Determine the affected muscle

Since the ulnar nerve innervates the hypothenar muscles, a complete functional loss of this nerve will directly affect the abductor digiti minimi.

Answer:

• A Abductor digiti minimi (Correct answer)
• B Abductor pollicis brevis
• C Flexor carpi radialis
• D Brachioradialis
• E Extensor indicis