All joints
Joint guide
Thumb CMC (saddle) joint
The thumb’s base joint is shaped like a saddle so the thumb can swing out, rotate, and meet the fingertips — the foundation of pinch and grip.
Diagram
Schematic for orientation — not a substitute for imaging or an in-person exam.
Related anatomy topics
Sources & further reading
We cite major society patient education, NIH institute pages, and MedlinePlus for naming and general joint context. Links open in a new tab; access dates help you judge currency when guidelines update.
- Arthritis of the thumb (thumb CMC / basal joint context) — OrthoInfo — American Academy of Orthopaedic Surgeons(accessed 2026-04-24)
- Hand and wrist anatomy — American Society for Surgery of the Hand(accessed 2026-04-24)
- Arthritis of the hand — OrthoInfo — American Academy of Orthopaedic Surgeons(accessed 2026-04-24)