BY JACOB WOODS 12G
Synovial joints are characterised by a layer of synovial fluid surrounding the articulating surfaces. This helps to lubricate the cartilage therefore reducing the friction between the joints. The synovial capsule stores the fluid, meaning it can lubricate the joint quickly. There are 5 types of synovial joint. They are as follows. Ball and socket joint
Spheroidal joints to give them their technical name are joints that include two articular surfaces; a ball shaped head that fits into a cup shaped socket ( hence the name). It allows for stable movemnt in many different directions without slippage. Movemnets such as flexion, abduction, adduction, extension and circumduction all occur freely here. An example of a ball and socket joint is the hip (femur-acetabulum), as well as the shoulder and the talo-calcaneonavicular joint. Hinge joint
In this type of joint, the articular surfaces are pulley shaped. It allows for stable flexion due to the presence of strong collateral ligaments. However, only one plane of movement is allowed via this joint via a transverse axis. Examples of Hinge joints are elbow joint, the ankle joint and the interphalangeal joint (joint in the finger) Pivot Joints
Pivot joints are joints that have a central bone that is used as a pivot point for another bone. This means that rotational movement around a vertical axis is accessible without sideways displacement or bending. This is aided by a flexible layer of ligament tissue, known as an osteo-ligamentous ring. Examples of this type of joint are the superior and inferior radio-ulnar joints, the median atlantoaxial joint (one of the joints in the neck).
Saddle joints are named so as they have two articular surfaces that sit on each other in a stable way_ much like a horse rider and the horse. The surfaces here are both different; one is convex, one is concaved. This allows bending motions in many different planes of movement. An...
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