Abductor digiti minimi muscle of hand in three slips that are inserted into the ulnopalmar margin of the proximal phalanx, the palmar plate of the metacarpophalangeal joint, and the sesamoid bone when present. Some fibers insert into the finger's dorsal aponeurosis, which is why the muscle acts similar to a dorsal interosseus muscle. Additionally, the ulnar-most portion of the tendon inserts into the little finger's digital cord, and the muscle thus forms part of a structure that flexes the metacarpophalangeal joint and extends the interphalangeal joints. It is innervated by the deep branch of the ulnar nerve (C8–T1). The abductor digit minimi develops at an early
Flexor carpi ulnaris muscle Flexor carpi ulnaris muscle The flexor carpi ulnaris muscle (or FCU) is a muscle of the human forearm that acts to flex and adduct (medial deviation) the hand. Flexor carpi ulnaris muscle arises by two heads, humeral and ulnar, connected by a tendinous arch beneath which the ulnar nerve and artery pass. Its insertion is into the pisiform bone, into the hamate bone via the pisohamate ligament and into the fifth metacarpal bone via the pisometacarpal ligament. The muscle acts to flex and adduct the wrist joint. The flexor carpi ulnaris muscle is innervated by the ulnar nerve which has