The flexor pollicis brevis is one of the intrinsic muscles of the hand within the thenar group.
The intrinsic muscles of the hand are involved with precision movements and consist of the following muscles:
- Thenar muscles: flexor pollicis brevis, abductor pollics brevis, opponens pollicis
- Hypothenar muscles: abductor digiti minimi, flexor digiti minimi brevis, opponens digiti minimi
- Interosseus muscles
- Other: palmaris brevis, adductor pollicis
The intrinsic muscles of the hand are innervated by the deep branch of the ulnar nerve, except the tehnar muscles and the lateral two lumbricals. A mnemonic for remembering this is Meat LOAF, Meat = Median nerve innervates the Lateral lumbricals, Opponens pollicis, Abductor pollicis brevis and Flexor pollicis brevis
At the wrist, the ulnar nerve divides into superficial and deep terminal branches.
Proximal to the wrist, the ulnar nerve gives off a dorsal branch, which itself divides into 2-3 dorsal digital nerves suppling the little finger and medial side of the ring finger.
Superficial terminal branch
Deep terminal branch