# Muscles of the Hand

> Intrinsic hand muscles — thenar, hypothenar, lumbricals and interossei with median and ulnar nerve supply, claw hand and MBBS Anatomy exam points.

- Canonical URL: https://prepelephant.com/topics/mbbs/anatomy/hand-muscles
- Exam / course: MBBS · Subject: Anatomy
- Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team
- First published: 2026-10-02
- Last updated: 2026-10-02
- How to cite: "Muscles of the Hand", PrepElephant, https://prepelephant.com/topics/mbbs/anatomy/hand-muscles

## Direct answer

The intrinsic muscles of the hand comprise the thenar, hypothenar, lumbrical and interosseous muscles with palmaris brevis. The median nerve, through its recurrent branch, supplies abductor pollicis brevis, flexor pollicis brevis (superficial head), opponens pollicis and the lateral two lumbricals; the ulnar nerve, through its deep branch, supplies everything else — the medial two lumbricals, all interossei, adductor pollicis, the deep head of flexor pollicis brevis and the three hypothenar muscles. In short, all small muscles of the hand are ulnar except the LOAF group.

## What you must remember

- **Thenar group:** abductor pollicis brevis, flexor pollicis brevis and opponens pollicis from the median nerve; adductor pollicis and the deep head of flexor pollicis brevis from the deep branch of the ulnar nerve.
- **Hypothenar group:** abductor digiti minimi, flexor digiti minimi and opponens digiti minimi, all from the deep branch of the ulnar nerve.
- **Lumbricals:** the lateral two are unipennate and median; the medial two are bipennate and ulnar — unipennate with median, bipennate with ulnar.
- **Interossei:** three palmar and four dorsal, all ulnar; palmar interossei adduct the fingers (PAD) and dorsal interossei abduct them (DAB) relative to the axial line through the middle finger.
- **Combined action:** lumbricals and interossei insert into the extensor expansion, flexing the metacarpophalangeal joints while extending the interphalangeal joints — the basis of the claw deformity when they are paralysed.
- **Palmaris brevis:** the only muscle of the superficial branch of the ulnar nerve; it wrinkles the hypothenar skin and improves the grip.
- **Clinical pictures:** ulnar palsy claws the ring and little fingers with interosseous wasting and Froment's sign; median palsy wastes the thenar eminence and loses opposition — benediction hand on clenching.

## Common confusion

Do not mix the two classic deformities. Claw hand — hyperextension at the knuckles with flexed interphalangeal joints of the ring and little fingers — is ulnar; the hand of benediction appears in a median lesion when the patient tries to make a fist. Adductor pollicis is ulnar, not median, which is why Froment's sign belongs to ulnar palsy.

## Exam-focused takeaway

For theory, draw a palmar dissection showing thenar and hypothenar groups, lumbricals on the flexor digitorum profundus tendons and interossei inserting into the extensor expansion. In viva, expect PAD and DAB, the LOAF rule, and the deformities of ulnar and median lesions. For spotters, identify the recurrent branch at the wrist, which is cut in injuries at the thenar base.

## Frequently asked questions

### Which intrinsic muscles are supplied by the median nerve?

Abductor pollicis brevis, flexor pollicis brevis (superficial head), opponens pollicis and the lateral two lumbricals — the LOAF group.

### Which are supplied by the deep branch of the ulnar nerve?

All interossei, the medial two lumbricals, adductor pollicis, deep head of flexor pollicis brevis and the hypothenar muscles; palmaris brevis from the superficial branch.

### What do PAD and DAB stand for?

Palmar interossei adduct and dorsal interossei abduct the fingers, relative to the axial line through the middle finger.

### Why does claw hand develop in ulnar palsy?

Paralysed lumbricals and interossei cannot flex the metacarpophalangeal joints or extend the interphalangeal joints, so long extensors hyperextend the knuckles and long flexors curl the medial two digits.

### What is Froment's sign?

On gripping a paper sheet, the affected thumb flexes at its interphalangeal joint, because flexor pollicis longus substitutes for the paralysed adductor pollicis.