01 / Location & anatomical relationships
At the joints along your fingers, especially where they meet the palm.
02 / Structure & organization
Knuckle commonly refers to the visible prominence of a metacarpophalangeal or interphalangeal joint. Joint capsules, ligaments, cartilage and tendons support each articulation. The prominence becomes more obvious when the joint flexes.
03 / Function
Knuckles let your fingers bend and straighten.
04 / Mechanism
The rounded end of one bone moves against the next bone. Cartilage and joint fluid help the surfaces slide, while tendons pull from either side. The bump you see changes shape as the joint bends.
Part of a bigger picture
The knuckle belongs in our arms & hands collection. Explore the nearby parts to see how this area of the body fits together.
Explore arms & hands →FOR DEEPER STUDY
Connect structure with function
Identify which joint is being described: the joint at the finger base differs structurally and functionally from the hinge joints farther along the finger.
Check your understanding
Locate the knuckle in relation to its neighbors. Explain how the structural features described above support its function, then distinguish it from a nearby structure with a different role.
Keep learning
Continue with OpenStax Anatomy and Physiology for system-level study. This atlas is educational and has not undergone independent medical peer review.