Muscular branches of ulnar nerve

The muscular branches of ulnar nerve arise in the forearm and the palm regions.

Muscular Branches in the Forearm

The ulnar nerve gives off motor branches to two muscles in the anterior forearm:

• Flexor Carpi Ulnaris: The ulnar nerve innervates this muscle, which functions to flex and adduct the wrist (ulnar deviation). The nerve enters the muscle as it passes between its two heads near the medial epicondyle of humerus.

• Medial Half of the Flexor Digitorum Profundus: The medial portion of this deeper muscle (serving the ring and little fingers) receives its motor supply from the ulnar nerve.

Muscular Branches in the Palm

As the ulnar nerve transitions into the palm, it divides into two terminal branches: the superficial branch and the deep branch, both of which provide motor innervation to specific muscles.

a. From the Superficial Branch

Palmaris Brevis: The superficial branch of the ulnar nerve innervates the palmaris brevis, a small muscle located over the hypothenar eminence. This muscle assists in deepening the hollow of the palm, aiding in grip.

b. From the Deep Branch

The deep terminal branch of the ulnar nerve is the primary motor branch in the hand, supplying many intrinsic hand muscles: The

• The hypothenar Muscles: These muscles control movements of the little finger and include: Abductor Digiti Minimi, Opponens Digiti Minimi, and Flexor Digiti Minimi.

• Lumbricals (Medial Two): The third and fourth lumbricals (serving the ring and little fingers) are innervated by the ulnar nerve. These muscles flex the metacarpophalangeal joints and extend the interphalangeal joints of their respective fingers.

• Interossei (Both Palmar and Dorsal): The palmar interossei are involved in finger adduction (toward the midline of the hand). The dorsal interossei facilitate finger abduction (away from the midline).

• Adductor Pollicis: This muscle, which brings the thumb toward the palm (adduction), is also supplied by the ulnar nerve.

• Occasionally the Deep Head of the Flexor Pollicis Brevis

Summary table