20 December 2013

Body Movements (Joints, Bones and Skeleton)

Joints and their Types

The point at which two separate bones meet is called a joint. 
There are four types of joints in the human body.They are:

1.Ball and socket joint
  • One end of a bone is rounded and ball-like, and fits into a cup-like depression of the other bone.
  • This joint provides movement in any direction.
  • Shoulder joints and hip joints are examples.
  • In the shoulder joint, the head of the humerus fits into a socket of the shoulder girdle.
  • In the hip joint, the large ball-like head of the femur fits into the deep socket of the hip girdle.

2.Hinge joint

  • This joint moves like a hinge in one plane only, just like the hinge of a door.
  • The elbow joint between the humerus and the ulna.
  • The joints between the bones of the fingers and toes, and less perfectly, the knee joint.
  • Hinge joints usually give sufficient power, because there is less danger of twisting at the joint.

3.Pivot joint

  • One bone rotates over a pivot-like end of the other bone.
  • The skull rotates on the upper end of the back bone.

4.Fixed Joint

  • In this joint, no movement is possible between the two bones.
  • The sutures between the bones of the cranium are an example.

Bones and Skeleton

  • The skeleton is a framework of all the bones in the human body.
  • The skeleton consists of the skull, hand bone, shoulder bone, rib cage, pelvic bone, backbone, leg bone and cartilage.
  • The skull protects the brain.
  • The shoulder has the ball and socket joint that helps the arm swing.
  • The rib cage protects the lungs, heart, stomach, abdomen and liver.
  • The backbone runs from the top of the skeleton to the bottom of the skeleton. It is connected to all the bones.
  • The pelvic bone protects the lower abdominal organs such as the urinary bladder, rectum and uterus.
  • Cartilage is a soft bone tissue that connects joints. It is present in external parts like the ear and nose.

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