Back interosseous muscles

Back interosseous muscles , mm. Interossei dorsales, number four, have the shape of spindle-shaped bicuspid muscles and lie in the interosseous spaces of the dorsal surface of the pastern. Each muscle begins with two heads from the side surfaces of the bases of each two adjacent metacarpals facing each other and is attached: the first and second muscles to the radial edge of the index and middle fingers, and the third and fourth to the elbow of the middle and ring fingers.

Function: two muscles of the radial margin pull the proximal phalanges of the index and middle fingers toward the thumb of the hand; Two muscles of the elbow margin pull the middle and ring fingers in the direction of the little finger. In addition, all muscles participate in the bending of the proximal phalanges and the straightening of the middle and distal phalanges of the index, middle, ring finger and little finger.

Innervation: n. Ulnaris (CVIII-ThI).

Blood supply: arcus palmaris profundus, aa. Metacarpales dorsales.