Joints
Joint: a place where two or more bones meet.
 Joints act as points of leverage and movement,
 Joints are also important as areas of growth and as sites that absorb and
transmit forces.
 An articulation (joint) is a point of contact between bones, or between
cartilage and bones.
 All body movements occur at joints, and almost all permit movement. A
few joints do not permit movement, but provide protection eg the sutures
of the cranium.
Types of joints
Joints are classified by means of their structure and by the amount of
movement that they allow.
1. Fixed/Fibrous/Synarthrosis(es): the articulating bones are united by fibrous
connective tissue, and these joints are found where a limited amount of
movement is desirable. eg. sutures of the cranium
2. Partly moveable/Cartilaginous/Amphiarthrosis(es): the articulating bones
are united by hyaline cartilage or fibrocartilage ie. there is cartilage
between the bones of the joint. Limited movement is possible. eg. between
the vertebrae, between the ribs and sternum.
3. Fully moveable joints/Synovial/Diarthrosis(es): these joints possess a
significantly large joint capsule, which is enclosed by a strong fibrous
capsule, lined by a synovial membrane which exudes synovial fluid. The
fluid bathes the internal surfaces of the joint and the articular cartilage that
covers the bone surfaces, acting as both lubricant and nutrient. These
joints demonstrate a considerable degree of movement. There are six
different types of synovial joint.
 Ball and socket
 Hinge
 Condyloid
 Pivot
 Gliding
 Saddle
The types of synovial joint allow different degrees of movement, but are
similar in structure and share common features.
 Articular/joint capsule
 Articular/hyaline cartilage
 Articular discs
 Synovial membrane
 Synovial fluid
 Ligaments
 Bursa