THE JOINTS

A joint is a place where two or more bones meet or articulated.

Types of Joint

Immovable joint

These are joints or regions where two or more bones are firmly attaches to one another or firmly fixed by ligament in such a way that movement of these bones are not possible. Example of some places in the body where

Immovable joints are present are skull and pelvic girdle.

The immovable joint of the skull are called suture

MOVABLE JOINTS

They are joint or region of the body where movement of joint is possible. Most of the bones are held together by movable joint

Types of movable joint

1. Ball and socket joint

These are joints that allow movement in all directions <360⁰>the joint are found in the shoulder and hip joint

.      2. Hinge joints

It is found at the elbows and knee it allow movement in only one direction

        3. Gliding and sliding joint

It allows gliding of the bones over one another. Example of this joint are found in the wrist and ankle

           4. Pivot joint

Pivot  joint are found in the neck between the atlas and axis. It permits nodding and rotation of one part of the body on another Structure of joint.

The main part of the joint consist of the followings

Ligament

These are though partly elastic bands of tissue which hold two bones together at a joint

Tendons are extension of connecting tissue which join muscle to the bones

Articular cartilage these are found at the surface of the bones at joint plays the role of cushioning by protecting them from wear and tear during movement

Synovial Membrane  is responsible for the secretion of synovial fluid

Synovial fluid is the fluid which lubricate the joint and thus reduce shock as well as friction between bone.

Capsule is the space which contain the synovial fluid

Movement

The skeleton can be move due to the muscular contraction. Muscle are joined to the bone by means of tendons . Tendon transmit the pull from a muscle into the bone, antagonist pair of muscle work against each  other moving the same limb into opposite direction, thus the biceps bend the  arm while  the triceps straightened. The contraction of the flexor muscle attains elongation of the biceps. The flexor muscle antagonistic pair i.e triceps the limbs while the extensor muscle e.g triceps straighten the arm.

FUNCTIONS OF SKELETON (Review)

1.It gives support ,shape, and rigidity

2.It protects the delicate organs of the body such as the brain, spinal cord and heart

3.It helps in movement

4.The bone marrows manufacture the red blood cells

5.It provides space for the attachment of the muscles

6.The ribs and sternum help the respiration

7.The skeleton stores some mineral salt e.g calcium and phosphorus