Muscle · Upper limb
Flexor digiti minimi brevis of the hand: origin, insertion, action and innervation
The flexor digiti minimi brevis of the hand runs from the hamate to the little finger. It flexes the little finger and is supplied by the deep ulnar nerve.
Quick answer
- Latin name
- Musculus flexor digiti minimi brevis manus
- Origin
- Hook of the hamate (carpal bones) and the flexor retinaculum
- Insertion
- Ulnar side of the base of the proximal phalanx of the little finger, together with the abductor digiti minimi
- Action
- Flexes the little finger at the metacarpophalangeal joint
- Innervation
- Deep branch of the ulnar nerve (C8-T1)
- Blood supply
- Deep palmar branch of the ulnar artery
See it on the 3D body
The flexor digiti minimi brevis of the hand lit on the 3D forearm and hand, as in the forearm and hand quiz. Turn the body, peel the layers, tap any structure for its name.
The flexor digiti minimi brevis of the hand is a small hypothenar muscle that bends the little finger at its knuckle. It runs from the hook of the hamate to the base of the little finger's first phalanx and is supplied by the deep branch of the ulnar nerve.
Where it is
The flexor digiti minimi brevis sits in the hypothenar eminence, the pad of the palm below the little finger. It is the superficial hypothenar muscle closest to the center of the palm:
- on its medial side, toward the edge of the hand, is the abductor digiti minimi;
- under it lies the opponens digiti minimi, the deepest of the group.
Its size varies from one person to another. In some hands it is hard to separate from the abductor, because the two insert together.
The name reads: flexor (bends), digiti minimi (of the little finger), brevis (short). "Short" separates it from the long flexors of the forearm, whose tendons also reach the little finger. "Of the hand" separates it from the muscle of the same name in the foot.
Between the abductor and the flexor, near the wrist, there is a small gap. The deep branch of the ulnar nerve and the deep palmar branch of the ulnar artery pass through it on their way into the deep palm.
Origin and insertion
- Origin: the hook of the hamate, a curved projection on the palm side of one of the wrist bones (see the carpal bones), and the flexor retinaculum, the band that roofs the carpal tunnel.
- Insertion: the ulnar side of the base of the proximal phalanx of the little finger, sharing its tendon area with the abductor digiti minimi.
The hook of the hamate also serves as the origin of the opponens digiti minimi, so two of the three hypothenar muscles start there. See the phalanges of the hand for the insertion.
What it does
- Flexion at the knuckle: it bends the little finger at the metacarpophalangeal joint, the joint between the fifth metacarpal and the proximal phalanx.
- Help in cupping the hand: together with the opponens digiti minimi, it brings the little finger forward and helps deepen the hollow of the palm, as when you cup water in your hand.
It does not bend the two joints inside the finger. Those are flexed by the long forearm flexors: the flexor digitorum superficialis for the middle joint and the flexor digitorum profundus for the joint near the tip. The flexor digiti minimi brevis mirrors the flexor pollicis brevis on the thumb side of the palm.
Innervation and blood supply
It is supplied by the deep branch of the ulnar nerve (roots C8 and T1), which gives twigs to the hypothenar muscles soon after it leaves the main ulnar nerve near the pisiform. The deep branch then turns into the deep palm to supply the dorsal interossei, the palmar interossei and the adductor pollicis.
Its blood comes from the deep palmar branch of the ulnar artery, which runs with the nerve.
How to remember it
- Hamate hook, hypothenar home: the flexor and the opponens of the little finger both start on the hook of the hamate; the abductor starts on the pisiform.
- Short flexor, one joint: brevis means it stays in the hand and bends only the knuckle.
- Nerve through the gap: the deep ulnar nerve slips between the abductor and the flexor digiti minimi brevis.
- Mirror image: thumb side, flexor pollicis brevis; little-finger side, flexor digiti minimi brevis.
Test yourself in the forearm and hand quiz, and find the hamate and its hook on the bones of the hand page.
Frequently asked questions
What does the flexor digiti minimi brevis of the hand do?
It flexes the little finger at the metacarpophalangeal joint.
Where does the flexor digiti minimi brevis originate?
From the hook of the hamate and the flexor retinaculum.
Which nerve supplies the flexor digiti minimi brevis of the hand?
The deep branch of the ulnar nerve (C8-T1), which passes right beside it.
Does the flexor digiti minimi brevis bend the whole little finger?
No. It only bends the knuckle. The two joints inside the finger are bent by the flexor digitorum superficialis and profundus from the forearm.
