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Image : “The front and back of a human right hand” by Evan-Amos. License: CC BY-SA 3.0
Many of the muscles that move the hand and fingers are reviewed in the Anatomy of the Upper Limb – Muscles of the Arm article.
The other muscles of the hand are divided into 3 groups: the intrinsics, the thenars, and the hypothenars.
Lumbricals
| Muscles | Origin | Insertion | Nerve supply | Function |
| Lumbricals (I-II) | Lateral two tendons of FDP (unipennate) | Lateral surfaces of extensor expansions of digits 2—5 | Median nerve (T1) | Flex metacarpophalangeal and extend interphalangeal joints of digits 2—5 |
| Lumbricals (III-IV) | Medial two tendons of FDP (bipennate) | Deep branch of ulnar nerve (T1) |
The lumbricals are four narrow muscle bellies which have no direct bony anchoring. They also stabilize the metacarpophalangeal joints and prevent an ulnar deviation.
Interossei Muscles
| Muscle | Origin | Insertion | Nerve supply | Function |
| Dorsal interossei | Dorsal sides of all metacarpals (bipennate) | Base of proximal phalanges and extensor expansions (digits 2—4, dorsal; digits 2, 4 and 5, palmar) | Deep branch of ulnar nerve (T1) | Abduct digits 2—4 away from axial line |
| Palmar interossei | Palmar sides of metacarpals 2, 4 and 5 | Adduct digits 2, 4 and 5 toward axial line |
The radial artery passes through between the two heads of the dorsal interosseous muscle I. There are three palmar interossei muscles and they are one-headed and lie between the metacarpal bones.
Thenar Muscles
| Muscles | Origin | Insertion | Nerve supply | Function |
| Opponens policis | Flexor retinaculum and tubercles of scaphoid and trapezium | Lateral side of the first metacarpal | Recurrent branch of median nerve (C8) | Oppose thumb |
| Abductor pollicis brevis | Lateral side of proximal phalanx of digit 1 | Abducts thumb; supports the opposition | ||
| Flexor pollicis brevis | Flexes thumb | |||
| Adductor pollicis | Oblique head: Base of second and third metacarpals and capitate Transverse head: anterior surface of the third matacarpal |
Medial side of proximal phalanx of thumb | Deep branch of ulnar nerve (C8) | Adducts thumb |
Hypothenar Muscles
| Muscles | Origin | Insertion | Nerve supply | Function |
| Palmaris brevis | Transverse carpal ligament and palmar aponeurosis | Ulnar palm | Ulnar nerve | Wrinkles the skin of the medial palm |
| Abductor digiti minimi | Pisiform | Medial side of proximal phalanx of the fifth digit | Deep branch of ulnar nerve (T1) | Abducts the fifth digit |
| Flexor digiti minimi brevis | Hook of hamate and flexor retinaculum | Flexes proximal phalanx of the fifth digit | ||
| Opponens digiti minimi | Medial border of the fifth metacarpal | Rotates and draws anteriorly fifth metacarpal |
Review Questions
The solutions can be found below the references.
1. Which of the following structures does not serve as the origin of the extensor digitorum muscle?
- Lateral epicondyle humeri
- Radial collateral ligament
- Os hamatum
- Annular ligament of the radius
- Antebrachial fascia
2. Which of the following muscles does not belong to the group of thenar muscles?
- Abductor pollicis longus muscle
- Flexor pollicis brevis muscle
- Abductor pollicis brevis muscle
- Adductor pollicis muscle
- Opponens pollicis muscle
3. Which of the following muscles passes through the 3rd tendon compartment?
- Extensor pollicis longus muscle
- Extensor pollicis brevis muscle
- Abductor pollicis longus muscle
- Abductor pollicis brevis muscle
- Adductor pollicis muscle
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