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Abductor pollicis longus muscle

Dr Daniel J Bell ◉ and Dr Elena Trajcevska et al.

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 1^stextensor 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 1^stmetacarpal, 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 ⁴
a vertical septum splitting the 1^stextensor compartment into two distinct subcompartments (i.e. APL lies in its own tunnel) ⁴

References

Anatomy: Upper limb

Anatomy: Upper limb

skeleton of the upper limb
- clavicle
  - conoid tubercle
  - supraclavicular foramen
- scapula
- humerus
  - supracondylar spur
  - olecranon foramen
- radius
- ulna
- carpal bones (mnemonic)
  - scaphoid
    - bipartite scaphoid
  - lunate
    - lunate morphology
  - triquetrum
  - pisiform
  - trapezium
  - trapezoid
  - capitate
  - hamate
  - variants
    - carpal coalition
      - lunotriquetral coalition
      - capito-hamate coalition
- metacarpals
- phalanges
  - terminal tuft
- accessory ossicles of the upper limb
  - accessory ossicles of the shoulder
    - os acromiale
  - accessory ossicles of the elbow
    - os supratrochleare dorsale
    - patella cubiti
  - accessory ossicles of the wrist (mnemonic)
    - os centrale carpi
    - os epilunate
    - os epitriquetrum
    - os styloideum
    - os hamuli proprium
    - lunula
    - os triangulare
    - trapezium secondarium
    - os paratrapezium
    - os radiostyloideum (persistent radial styloid)
joints of the upper limb
- pectoral girdle
  - shoulder joint
    - articulations
    - associated structures
    - movements
      - scapulothoracic joint
        
        scapular retraction (adduction)
        
        scapular protraction (abduction)
        
        scapular elevation
        
        scapular depression
        
        scapular lateral rotation
        
        scapular medial rotation
      - glenohumeral joint
        
        arm flexion
        
        arm extension
        
        arm abduction
        
        arm adduction
        
        arm internal rotation (medial rotation)
        
        arm external rotation (lateral rotation)
        
        circumduction
    - blood supply - scapular anastomosis
    - ossification centers
- elbow joint
  - proximal radioulnar joint
  - ligaments
    - medial (ulna) collateral ligament complex
    - lateral (radial) collateral ligament complex
      - lateral ulnar collateral ligament
  - associated structures
  - movements
  - alignment
  - blood supply - elbow anastomosis
  - development
    - elbow ossification (mnemonic)
    - elbow ossification centers
- wrist joint
  - articulations
  - ligaments
    - intrinsic ligaments
    - extrinsic ligaments
  - associated structures
    - extensor retinaculum
    - flexor retinaculum
    - joint capsule
  - movements
  - alignment
  - ossification centers
- hand joints
  - articulations
    - carpometacarpal joint
      - triscaphe joint
    - metacarpophalangeal joints
      - palmar ligament (plate)
      - collateral ligament
    - interphalangeal joints
      - palmar ligament (plate)
      - collateral ligament
  - movements
  - ossification centers
spaces of the upper limb
muscles of the upper limb
blood supply to the upper limb
- arteries
- veins
innervation of the upper limb
- intercostobrachial nerve
- brachial plexus (mnemonic)
  - branches from the roots
  - branches from the trunks
    - suprascapular nerve
  - branches from the cords
    - lateral cord
      - lateral pectoral nerve
    - posterior cord
    - medial cord
  - terminal branches
    - ulnar nerve
    - radial nerve
      - posterior interosseous nerve (deep radial nerve)
      - superficial radial nerve
    - musculocutaneous nerve
    - axillary nerve
    - median nerve
      - anterior interosseous nerve
      - bifid median nerve
lymphatic drainage of the upper limb
- axillary lymph nodes

Article information

rID: 24510

System: Musculoskeletal

Section: Anatomy

Tag: stub, cases, cases, stub, muscle, upper limb

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 Figure 1: extensor compartments of the wrist

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