JOINTS

| General| Fibrous Joints| Cartilagenous Joints| Synovial Joints|

General

We have already learnt that the human skeleton consists of more than 200 bones. The individual bones are attached in such a way that a large variety of co-ordinated movements are made possible in different parts of the body. These movements are made possible by skeletal muscles, the fact that the bones act as levers, cartilage which reduces fricton and ligaments which prevent dislocation and the presence of movable joints. The site or place where 2 or more bones of the skeleton are attached to each other is called a joint or place of articulation.

A joint can be defined as follows:

A joint or place of articulation is formed where 2 or more bones come inclose contact in the body and are attached to each other by ligaments or cartilage.

Types of Joints

Joints can be classified according to the degree and type of movement they allow. The following types of joints can be recognized:

Fibrous (or Immovable) Joints.

These joints are firmly held together by a thin layer of strong connectice tissue. There is no movement between the bones such as the sutures of the skull and the teeth in their sockets.

Fibrous joints (sultures in the skull).
Cartilagenous Joints.

Cartilagenous joints are joints where the articular surfaces of the bones forming the joints are attached to each other by means of white fibrocartilaginous discs and ligaments which allow only a limited degree of movement. Examples are the cartilaginous between the vertebrae, the cartilage in the symphysis which binds the pubic bones together at the front of the pelvic girdle and the cartilage in the joint between the sacrum and the hip bone.

Cartilaginous joints between the thoracic vertebrae.
Synovial Joints.

These are freely movable joints. Most of the joints in the body are of the synovial type. The following are the main characteristics of a synovial joint:

A generalized synovial joint.

Synovial joints can be subdivided into the following groups according to the type of movement they carry out:

Model showing compound joints
in the neck region.