Question

The bones at the elbow are joined by a

Answer 1

Hint: Light body weight and mechanical force is exerted on these joints, so they are made up of simple synovial joint material with tiny accessory ligaments for reinforcement.

Complete answer:
Hinge joint connects the bones at the elbow. Hinge joint is a synovial joint and it includes the ankle, elbow, and knee joints. Hinge joints are formed between two or more bones where the bones can only move along in one axis to extend. The simplest hinge joints in the body are the interphalangeal joints which are found between the phalanges of the fingers and toes. In these types of hinge joints, the bones are able to flex to decrease the angle between them. It is like when making a fist or curling the toes and extending to increase their angle to about 180 degrees when holding the foot or hand flat.
The elbow is a complex hinge joint which is formed between the humerus of the upper arm and the ulna and radius of the forearm. The elbow is subjected to much stronger forces than the fingers and toes, and so it contains several strong accessory ligaments and unique bone structures that reinforce its structure.

Additional information:
- Each bone is covered with a thin layer of smooth hyaline cartilage to reduce friction in the joint and to absorb the shock of the joint being compressed.
- The bones are surrounded by a capsule of tough fibrous connective tissue lined with synovial membrane.
- The joint capsule at these joints forms the knuckle that is visible through the skin that covers it.

Note: Synovial joints allow bones to slide past each other or to rotate around each other. Oily synovial fluid produced by the synovial membrane helps in lubricating the joint to reduce friction and ensure movement of the hinge joints.