Name

# Dorsal Interossei (hand)

Pronunciation

(DOR-sal In-ter-OSS-e-ey e)

Origin/Proximal Attachment

Between each metacarpal

Insertion/Distal Attachment

Directly distal to the origin on the base of the proximal phalanges 2 – 4, closest to the midline; extensor hood of the same digit/s

Action/Relevance

Abducts the fingersFlexes the fingers (at the MCP while IP joints are extended)

Innervation

Ulnar nerve - deep branch (C8, T1)

Notes

The Dorsal interossei are four in number, and occupy the intervals between the metacarpal bones. They are bipenniform muscles, each 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 first phalanges and into the aponeuroses of the tendons of the Extensor digitorum communis. Between the double origin of each of these muscles is a narrow triangular interval; through the first of these the radial artery passes; through each of the other three a perforating branch from the deep volar arch is transmitted.