Extensor digitorum muscle

Last revised by Henry Knipe on 8 Feb 2023

Extensor digitorum (ED) muscle, also known as extensor digitorum communis (EDC) muscle, is a muscle of the superficial layer of the posterior compartment of the forearm and with other extensor muscles arises from a common tendon attached to the lateral epicondyle of the humerus. It is one of the extrinsic muscles of the hand.


Gross anatomy

ED represents a medial group of superficial extensor muscles. ED passes under the extensor retinaculum which holds it tight and passes through the 4th extensor compartment of the wrist, once it passes under the sagittal band of the metacarpophalangeal joint the tendon splits into three 'slips' consisting of two lateral slips and a central slip 1-3.

The central slip inserts at the dorsal surface of the base of the middle phalanx 1-3.

The lateral slips, run both sides of the proximal interphalangeal joints to then converge with the lumbrical and interosseous fibers to form conjoint tendons, that converge over the middle phalanx and insert at the dorsal aspect of the base of the distal phalanx as a single terminal tendon 1-3

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