Question

1. What are joints?
2. List and explain (3) structural classification of joints.
3. List and explain (3) functional classification of joints.

Answer 1

1.  Joint is the physical point of connection between two bones, they hold the skeleton together and support movement.

2. Structurally joints can be classified as,

a) Fibrous joints, in these joints, the adjacent bones are directly connected to each other by fibrous connective tissue, and thus the bones do not have a joint cavity between them, these joints can be of three types, Sutures which  are nonmoving joints that connect bones of the skull.eg, sutures between skull bones.Gomphoses, which are the fibrous articulations between the teeth and the mandible or maxilla, Syndesmosis a joint in which a ligament connects two bones,

b) Cartiliginous Joints, these are the joints that unite bones with cartilage, they are of two types, Synchrondosis, which is an immovable cartilaginous joint, eg, the first sternocostal joint. Symphysis consists of a compressable fibrocartilaginous pad that connects two bones, eg, hip joint, these type of joints allow some movement.

c) Synovial joint, also known as diarthrosis, is a connection between two bones consisting of a cartilage lined cavity filled with fluid, they are the most flexible type of joint between bones, because the bones are not physically connected and can move more freely in relation to each other.The different types of synovial joints are the ball-and-socket joint (shoulder joint), hinge joint (knee), pivot joint (atlantoaxial joint, between C1 and C2 vertebrae of the neck), condyloid joint (radiocarpal joint of the wrist), saddle joint(thumbs) etc.

3. The functional classification divides joints into three categories: synarthroses, amphiarthroses, and diarthroses.

Synarthrosis is a type of joint which permits very little or no movement,most synarthroses joints are fibrous. The sutures between bones of the skull is an example of synarthrosis joint.

Amphiarthrosis is a joint that has limited mobility, an example of this type of joint is the cartilaginous joint that unites the bodies of adjacent vertebrae.

Diarthroses are freely movable joint, in fact they are  most common and most movable type of joint in a mammal's body.eg, elbow and shoulder joint.