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 1st extensor compartment of the wrist before attaching distally. It is one of the extrinsic muscles of the hand.


Variant anatomy

  • presence of multiple slips instead of a single APL tendon 4
  •  a vertical septum splitting the 1st extensor compartment into two distinct subcompartments (i.e. APL lies in its own tunnel) 4
Anatomy: Upper limb

Anatomy: Upper limb

Article information

rID: 24510
Section: Anatomy
Synonyms or Alternate Spellings:
  • Abductor pollicis longus muscles
  • Abductor pollicis longus (APL)
  • APL muscle

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Cases and figures

  • Figure 1: extensor compartments of the wrist
    Drag here to reorder.
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