Chapter 9, Problem 1CP

On what basis are joints classified?

Summary Introduction

To review:

The basis on which the joints are classified in the human body.

Introduction:

A joint can be defined as the region of contact between the cartilage and the bone or between two bones. Flexible connective tissues hold the two or more bones together to allow movement along with better stability. These joints perform different functions based on their location and tasks.

Explanation of Solution

The joints are classified in two ways based on their structure or anatomical characteristics and function or types of movement permitted.

From a structural point of view, the joints are classified based on the kind of connective tissue, which binds the bones and the absence or the presence of the synovial cavity. Three types of joints based on the structure are as follows:

Fibrous joints: In this type, the bones are held together by the help of the dense irregular type of connective tissues that is rich in collagen fibers. There is an absence of synovial cavity in this joint type.

Cartilaginous joints: In this type, the bones are held together by cartilages. There is an absence of synovial cavity in this joint type.

Synovial joints: In this type, the bones forming the joint are encapsulated in a structure known as a synovial joint. The bones forming this joint are attached by dense and irregular type of connective tissue consisting of the articular capsule and some accessory structures like the ligaments.

From the functional point of view, the joints are classified by degree of movement permitted by the joint. The three types of joints based on the functional aspect are as follows:

Synarthrosis: In this type, the two bones are attached in such a way that there are absolutely no movements in the joint.

Amphiarthrosis: In this type, the bones are attached in such a way that the bones are slightly movable.

Diarthrosis: In this type, the bones are attached in such a way that the bones are allowed freedom of movement.

Conclusion

Thus, the joints are classified based on their structure and function.