Identify the three palmar interosseus muscles [second palmar interosseous muscle is indicated between the probes] [third palmar interosseous muscle]. They arise from metacarpal bones of digits 2, 4, and 5 and insert into the bases of the proximal phalanges and into the extensor expansions of the fingers.
The palmar interosseous muscles act as adductors by drawing the fingers toward an imaginary line drawn through the long axis of the middle finger. These muscles are innervated by motor fibers of the ulnar nerve.The four dorsal interosseus muscles will be identified when the dorsum of the hand is dissected in the next laboratory exercise.
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