Structure and function of Synovial Joint: Biology Lecture

Welcome to my channel, In this video you will learn about Structure of synovial joint and how each structure in synovial joint contributes in joint function.
A synovial joint is characterised by the presence of a fluid-filled joint cavity contained within a fibrous capsule.

It is the most common type of joint found in the human body, and contains several structures which are not seen in fibrous or cartilaginous joints.

Key Structures of a Synovial Joint:

The three main features of a synovial joint are: (i) articular capsule, (ii) articular cartilage, (iii) synovial fluid.

Articular Capsule
The articular capsule surrounds the joint and is continuous with the periosteum of articulating bones.

It consists of two layers:

Fibrous layer (outer) – consists of white fibrous tissue, known the capsular ligament. It holds together the articulating bones and supports the underlying synovium.
Synovial layer (inner) – a highly vascularised layer of serous connective tissue. It absorbs and secretes synovial fluid, and is responsible for the mediation of nutrient exchange between blood and joint. Also known as the synovium.

Articular Cartilage:

The articulating surfaces of a synovial joint (i.e. the surfaces that directly contact each other as the bones move) are covered by a thin layer of hyaline cartilage.

The articular cartilage has two main roles: (i) minimising friction upon joint movement, and (ii) absorbing shock.

Synovial Fluid
The synovial fluid is located within the joint cavity of a synovial joint. It has three primary functions:

Lubrication
Nutrient distribution
Shock absorption.
Articular cartilage is relatively avascular, and is reliant upon the passive diffusion of nutrients from the synovial fluid.

Accessory Structures of a Synovial Joint:

Accessory Ligaments:
The accessory ligaments are separate ligaments or parts of the joint capsule.
Bursae:
A bursa is a small sac lined by synovial membrane, and filled with synovial fluid.

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