Dorsal interossei of the hand

For the muscles of the foot, see Dorsal interossei muscles (foot).

Dorsal interossei of the hand
The Interossei dorsales of left hand.
Latin	musculi interossei dorsales manus
Gray's	subject #126 464
Origin	metacarpals
Insertion	proximal phalanges
Artery	Dorsal metacarpal artery and palmar metacarpal artery
Nerve	deep branch of ulnar nerve
Actions	abduct finger
Antagonist	Palmar interossei muscles

The dorsal interossei of the hand are muscles that occupy the space between the metacarpals.

Structure

There are four dorsal interossei in each hand. They are specified as 'dorsal' to contrast them with the palmar interossei, which are located on the anterior side of the metacarpals.

The dorsal interosseous muscles are bipennate, with each muscle arising by two heads from the adjacent sides of the metacarpal bones, but more extensively from the metacarpal bone of the finger into which the muscle is inserted. They are inserted into the bases of the proximal phalanges and into the extensor expansion of the corresponding extensor digitorum tendon. The middle digit has two dorsal interossei insert onto it while the first digit (thumb) and the fifth digit (little finger) have none.

#	Origin	Insertion
first	on the radial side of the second metacarpal and the proximal half of the ulnar side of the first metacarpal	on the radial side of the base of the second proximal phalanx (index finger) and the extensor expansion
second	on the radial side of the third metacarpal and the ulnar side of the second metacarpal	on the radial side of the third proximal phalanx (the middle finger) and the extensor expansion
third	on the radial side of the fourth metacarpal and the ulnar side of the third metacarpal	on the ulnar side of the third proximal phalanx (the middle finger) and the extensor expansion
fourth	on the radial side of the fifth metacarpal and the ulnar side of the fourth metacarpal	on the ulnar side of the fourth proximal phalanx (the ring finger) and the extensor expansion

The first dorsal interosseous muscle is larger than the others. Between its two heads, the radial artery passes from the back of the hand into the palm.

Between the heads of dorsal interossei two, three, and four, a perforating branch from the deep palmar arch is transmitted.

Innervation

All interosseous muscles of the hand are innervated by the deep branch of the ulnar nerve.

Actions

The primary action of the dorsal interossei is to: flex the metacarpophalangeal joint (MCP) and to extend the interphalangeal joints and thus assist the lumbricals. In addition, a secondary function is to abduct the fingers away from the middle finger. This is in contrast to the palmar interossei, which adduct the fingers. This is often remembered by the mnemonic DAB PAD, short for "Dorsal ABducts, Palmar ADducts".

Additional images

• 

  Bones of the left hand. Dorsal surface.

• 

  Tendons of forefinger and vincula tendina.

• 

  The muscles of the left hand. Palmar surface.

External links

• LUC dih
• UWASH interossei
• SUNY Labs 09:08-0101
• dorsal+interossei+%28interosseous+muscles%29+of+hand at eMedicine Dictionary
• Mnemonic at medicalmnemonics.com 293 96

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained within it may be outdated.