Proximal phalanx of thumb at a glance
- What it is
- The first of the thumb's two phalanges.
- Location
- Articulates with the first metacarpal at the metacarpophalangeal joint and the distal phalanx at the interphalangeal joint.
- Function
- Allows flexion and extension of the thumb, helping grip and pinch.
- Body system
- Skeletal · paired (left and right)
- FMA ID
- FMA65470 (Foundational Model of Anatomy)
Key facts
- The thumb has only two phalanges, proximal and distal.
- Abductor pollicis brevis and flexor pollicis brevis insert on the radial side of its base, adductor pollicis on the ulnar side, and extensor pollicis brevis on its dorsal base.
Clinical relevance
Rupture of the ulnar collateral ligament at its base, from forced abduction, is called skier's (or gamekeeper's) thumb.
Structures next to the proximal phalanx of thumb
The nearest named structures in the 3D model, measured from the centre of each part:
- Arteria princeps pollicis · cardiovascular
- Distal phalanx of thumb · skeletal
- Transverse head of adductor pollicis · muscular
- First metacarpal bone · skeletal
- Second metacarpal bone · skeletal
- Superficial head of flexor pollicis brevis · muscular
- Oblique head of adductor pollicis · muscular
- Flexor pollicis brevis · muscular
- Extensor indicis · muscular
- Dorsal interossei of hand · muscular
References
- Foundational Model of Anatomy: Proximal phalanx of thumb (FMA65470). EMBL-EBI Ontology Lookup Service.
- OpenStax. Anatomy and Physiology 2e, §7.1 Divisions of the Skeletal System. Rice University, 2022.
- Mitsuhashi N. et al. (2009). BodyParts3D: 3D structure database for anatomical concepts. Nucleic Acids Research 37, D782–D785. Data © The Database Center for Life Science, CC BY 4.0.
Related anatomy
Explore the whole body in the interactive 3D human anatomy model, or browse the A–Z list of human structures.