joints structure and classification

JOIN

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T HE A

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Y S T E M

JOINTSA joint can be defined as follows: A joint or place of articulation is formed where

2 or more bones come in close contact in the body and are attached to each other by ligaments or cartilage.

TYPES OF JOINTS: FIBROUS

Fibrous (or Immovable) Joints.

Held together by a thin layer of strong connective tissue.

No movement between the bones.

Sutures of the skull, teeth in their sockets.

TYPES OF JOINTS: CARTILAGENOUS

Cartilagenous Joints. The articular surfaces of

the bones forming the joints are attached to each other by white fibro-cartilaginous discs

Limited degree of movement.

Vertebral discs, the pubic symphysis.

TYPES OF JOINTS: SYNOVIAL

Freely movable joints.The ends of the bones

are covered with a layer of smooth hyaline cartilage.

Enclosed by a bag-like capsular ligament which holds the joint together and contains the synovial fluid.

TYPES OF JOINTS: SYNOVIAL

Lined with a Synovial membrane. This membrane secretes synovial fluid. The synovial fluid lubricates the joint.

The bones are also attached by ligaments. They prevent dislocation during normal movement.

CARTILAGE

Is a tough, generally smooth fibrous connective tissue found at the end of bones and between joints.

It protects bones by helping to absorb the impacts experienced during movement and physical activity

LIGAMENTSA strong,

fibrous band of connective tissue that holds together two or more moveable bones or cartilage.

“Connects bone to bone”

TENDONS

Are very strong and inflexible connective tissue that allow movement to occur by helping muscles pull on bones.

“Tendons connect muscles to bones”

SPECIFIC TYPES O

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BALL-AND-SOCKET JOINTS.

These joints are formed where the rounded head of one bone fits into the hollow, cup-shaped socket of another bone.

Freedom of movement in all directions.

Hip, shoulder.

HINGE JOINTS.

Movement is possible in one plane only.

Knee and the Elbow joints.

Hinge joints have ligaments mainly at the sides of the joints.

GLIDING JOINTS. Allow for gliding

movements between flat surfaces as they slide over one another.

Only a limited amount of movement is allowed

The joints between the carpal bones, the joints between the tarsal bones

PIVOT JOINTS. These joints occur

where:a bony ring rotates

round the pivot (axis) of another bone such as the ring-like atlas rotating around the odontoid process of the axis, allowing the head to turn from side to side.

The end of one bone rotates round the axis of another bone such as the end of the radius rotating around the ulna as the palm of the hand is turned inwards or outwards.

SADDLE JOINTS

Two saddle-like structures allowing backwards, forwards and sideways movements.

Thumb (between carpals and metacarpals)

Ankle (between fibula, tibia and tarsals)

CONDYLOID JOINT

Oval shaped head of bone in a shallow cavity, allowing backwards, forwards and sideways movement

Wrist (between radius and ulna and carpals)