Retract the tendons of the flexor digitorum superficialis muscle distally, and identify the four small lumbrical muscles . Each lumbrical muscle arises from the radial side of a tendon of flexor digitorum profundus muscle. Distally, each lumbrical muscle inserts into the extensor expansion of the same finger. (The extensor expansions will be dissected in the next laboratory exercise).
The lumbrical muscles act to flex the metacarpophalangeal (m/p) joint and extend the proximal and distal interphalangeal (i/p) joints of the finger. The first and second lumbrical muscles are innervated by the median nerve, whereas the third and fourth lumbrical muscles are innervated by the ulnar nerve.
Links and References: