Lumbricals of hand
The lumbricals of hand are the four intrinsic muscles of the fingers that originate from the tendon of the digitorum profundus. These muscles are distinctive for the differentiation between the medial and lateral pairs. Out of the four lumbricals, the first two are unipennate, originating from their respective tendons. The remaining two are bipennate, originating from the side of the two adjoining tendons. The first of these muscles arises from the digitorum profundus tendon to the index finger, and its insertion takes place on the lateral portion of the extensor digitorum. The second muscle goes to the middle finger, the third to the ring finger, and the fourth to the little finger. The innervation of the first and second muscles is done by the median nerve; the ulnar nerve innervates the third and fourth muscles. The lumbricals of hand receive blood supply from four different sources, including the dorsal digital artery, the superficial and deep palmar arches, and the palmar digital artery. These muscles perform the key function of flexing the metacarpophalangeal joints with support from the interosseous muscles.
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In Depth: Lumbricals of hand