abductor pollicis longus muscle

The abductor pollicis longus (APL) muscle is found in the deep layer of the posterior compartment of the forearm. As it descends, it becomes superficial and passes under the extensor retinaculum and through the 1extensor compartment of the wrist before attaching distally. It is one of the extrinsic muscles of the hand.

Summary

• origin: posterior surfaces of ulna, radius and interosseous membrane
• insertion: via tendon, usually dividing into two slips, one attaching to the base of 1metacarpal, the other attaching to the trapezium
• arterial supply: proximally by the posterior interosseous artery and distally by a branch from the anterior interosseous artery
• innervation: posterior interosseous nerve (C7, C8), a continuation of the deep branch of the radial nerve (C7, C8)
• action: abducts and extends the thumb at the carpometacarpal joint

Variant anatomy

• presence of multiple slips instead of a single APL tendon
•  a vertical septum splitting the 1extensor compartment into two distinct subcompartments (i.e. APL lies in its own tunnel)

Siehe auch:

• Tendovaginitis stenosans de Quervain

und weiter:

• Fingermuskulatur