Deep branch of ulnar nerve

The deep branch of ulnar nerve is a terminal branch of the ulnar nerve that plays a crucial role in the motor innervation of the hand's intrinsic muscles. It arises in the palm, following the division of the ulnar nerve into superficial and deep branches.

After branching off at the palm, the deep branch of ulnar nerve courses deeply into the hand by passing through Guyon’s canal, alongside the deep branch of the ulnar artery.

Muscular branches

In the palm, the deep branch of ulnar nerve ends up providing motor innervation to several muscles of the hand, including:

• Hypothenar muscles: Abductor digiti minimi, flexor digiti minimi, and opponens digiti minimi.

• Medial two lumbricals (3rd & 4th): These control the flexion of the metacarpophalangeal (MCP) joints and extension of the interphalangeal (IP) joints of the ring and little fingers.

• Interossei muscles: Both palmar (three) and dorsal interossei (four).

• Adductor pollicis: Provides adduction of the thumb, essential for strong grasping actions.

• Deep head of flexor pollicis brevis: Occasionally innervated by the deep branch, contributing to thumb flexion.

Articular branches

The deep branch also gives small articular branches that supply the wrist joint, aiding in proprioception and sensory feedback necessary for hand movements.