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Dorsal interossei of the hand
Template:Infobox Muscle 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".[1]
Additional images
- Gray220.png
Bones of the left hand. Dorsal surface.
- Gray416.png
Tendons of forefinger and vincula tendina.
- Gray427.png
The muscles of the left hand. Palmar surface.
References
- ↑ "Interossei of hand: actions". lifehugger. 2008-11-01. http://mc.lifehugger.com/moc/352/interossei-hand-actions. Retrieved 2009-04-26.
External links
- Template:MuscleLoyola
- Template:MuscleUWash
- SUNY Labs 09:08-0101
- dorsal+interossei+%28interosseous+muscles%29+of+hand at eMedicine Dictionary
- Template:MedicalMnemonics
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.
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