What is a hinge in your body?

In the human body, a hinge is a joint type that allows movement primarily in a single plane, resembling the motion of a door hinge. This type of joint generally has a concave and a convex surface that fit together, restricting movement to a back-and-forth motion while preventing side-to-side or rotational movements.

Examples of hinge joints in the body include:

1. Interphalangeal (IP) joints: These are the joints between the phalanges (finger bones), which allow for bending (flexion) and straightening (extension) of the fingers and toes.

2. Elbow joint (humeroulnar joint): The elbow joint is a hinge synovial joint formed between the trochlea of the humerus (upper arm bone) and the trochlear notch of the ulna (forearm bone).

3. Knee joint (tibiofemoral joint): The knee joint is a modified hinge joint that allows flexion and extension, with some limited rotational movements.

4. Ankle joint (talocrural joint): The ankle joint is a hinge joint formed between the talus (ankle bone) and the tibia (shin bone), allowing for up-and-down foot movements (dorsiflexion and plantarflexion).

These hinge joints are essential for body movement and various daily activities, such as walking, grasping objects, and writing.