The dorsal interossei (or dorsal interossei muscles, latin: musculi interossei dorsales) of the hand are four muscles that belong to the medial muscle group of the hand. The dorsal interossei lie deep between the metacarpal bones on the dorsal surface of the hand.
The dorsal interossei muscles originate from the adjacent sides of the first to fifth metacarpal bones.
The dorsal interossei muscles insert onto the proximal phalanges of the second, third and fourth fingers.
The main function of the dorsal interossei is to adduct the second and fourth finger in relation to the axis of the middle finger.
The dorsal interossei muscles of the hand are innervated by the ulnar nerve.