ICSE Class 9 Answered

In freely movable joints, there is a synovial cavity between two ends of the bone. It is filled with synovial fluid. These joints are capable of free movement. E.g. Elbow joint, Hip joint.

Types of freely movable joints:

(1) Ball and socket joint:

A ball and socket joint consists of a ball-like surface of one bone that fits into a cup-like cavity of another bone. It allows greatest freedom of movement in all directions. The hip joint and shoulder joint are the examples of ball and socket joint.

(2) Hinge joint:

A hinge joint is a joint in which the convex surface of one bone fits into the concave surface of another bone. This joint is a strong joint, but allows movement in one direction only. This movement can be up and down or backward and forward. Hinge joints are seen in the elbow, between the humerus and ulna.

(3) Pivot joint:

In pivot joint, a rounded, pointed or conical surface of one bone articulates within a ring formed partly by ligament. Pivot joints allow rotation about an axis. The joint where your neck joins the head is a pivotal joint.

(4) Gliding joint:

In gliding joint, the articulating surfaces of the bones are usually flat. The two flat surfaces glide or slide over one another and thereby, permit movement. Gliding joints allow side to side as well as backward and forward movement. Gliding joints are seen in the tarsal bones and the joint between the sternum and clavicle.