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First: Base of first
metacarpal bone, ulnar side. Second:
Length of second metacarpal bone, ulnar side. Third:
Length of fourth metacarpal bone, radial side. Fourth:
Length of fifth metacarpal bone, radial side.
Insertion: Into the extensor expansion of the respective digit, with possible attachment to base of proximal phalanx as follows: First: Ulnar side of thumb. Second: Ulnar side of index finger. Third: Radial side of ring finger. Fourth: Radial side of little finger.
Innervation: Ulnar, C8, T1
Action: Adduct the thumb, index, ring, and little finger toward the axial line through the third digit. Assist in flexion of MCP joints, and extension of IP joints of the three fingers.
Volar Intrinsic Superficial | Dorsal Intrinsic | Extrinsic Muscles | Muscle Arrangement | Help | Hand Kinesiology
Lorie Richards and Janice Loudon, University of Kansas
Medical Center, School of Allied Health,
Occupational and Physical Therapy Education, October 1997