Quick Facts
Origin: Posterior aspects of proximal half of ulna and middle one third of radius, adjacent interosseous membrane of forearm.
Insertion: Lateral aspect of base of first metacarpal bone.
Action: Abducts and extends thumb at first carpometacarpal joint.
Innervation: Posterior antebrachial interosseous nerve (C7-C8).
Arterial Supply: Anterior and posterior interosseous arteries.
Related parts of the anatomy
Origin
The abductor pollicis longus muscle originates from the:
- posterior aspect of proximal half of the body of ulna;
- posterior surface of middle one third of the body of radius;
- adjacent interosseous membrane of forearm.
Insertion
The fibers of the abductor pollicis longus muscle travel inferolaterally to the hand and insert onto the lateral aspect of the base of first metacarpal bone. It may also insert onto the trapezium bone.
Key Features & Anatomical Relations
The abductor pollicis longus muscle is one of the muscles of the deep part of the posterior compartment of the forearm. It is a long, fusiform type of skeletal muscle.
Superior to the wrist, the muscle belly gives rise to a tendon which travels inferolaterally, spiraling over the tendons of the brachioradialis and extensor pollicis longus and brevis muscles. At the wrist, its tendon travels deep to the extensor retinaculum of hand, along with the adjacent tendon of extensor pollicis brevis, where it passes through the common tendinous sheath of abductor pollicis longus and extensor pollicis brevis muscles. Within the hand, the tendon then travels inferolaterally to its insertion site.
The abductor pollicis longus muscle is located:
- anterior (deep) to the extensor digitorum and extensor digiti minimi muscles, the posterior interosseous artery, and the posterior antebrachial interosseous nerve;
- posterior (superficial) to the body of radius and adjacent interosseous membrane of forearm;
- lateral to the extensor pollicis longus and brevis muscles.
The tendons of both the abductor pollicis longus and extensor pollicis brevis form the anterior boundary of the anatomical snuff box, while the tendon of the extensor pollicis longus forms its posterior boundary.
Actions & Testing
The abductor pollicis longus muscle is involved in multiple actions:
- abducts the first metacarpal bone (of thumb) at the first carpometacarpal joint, which occurs when the abductor pollicis brevis muscle contracts simultaneously with it;
- extends the first metacarpal bone at the first carpometacarpal joint, which occurs when the extensor pollicis longus and brevis muscles contract simultaneously with it;
- assists in abduction of the hand at the radiocarpal (wrist) and midcarpal joints.
The abductor pollicis longus muscle can be tested by abducting the first metacarpal (of thumb) at its carpometacarpal joint against resistance. It can be seen and palpated along the anterior boundary of the anatomical snuff box (Sinnatamby, 2011).
List of Clinical Correlates
- de Quervain disease
References
Sinnatamby, C. S. (2011) Last's Anatomy: Regional and Applied. ClinicalKey 2012: Churchill Livingstone/Elsevier.
Standring, S. (2016) Gray's Anatomy: The Anatomical Basis of Clinical Practice. Gray's Anatomy Series 41st edn.: Elsevier Limited.
