Joints
Joints allow the body to move. Muscles attached to the bone contract to cause the bone to move. The bones act as levers with joints acting as pivots.
‘A joint is where to bones meet and muscles act together to cause movement’
Types of Joints
- Fixed or Immoveable Joints
These are joints and bones that can’t move, e.g. The Skull.
- Slightly Moveable Joints
They can only move a little bit and are held together by ligaments. E.g. The Ribs
- Freely Moveable/Synovial Joints
They have a high degree of movement. These are the largest group of joints found in the body. E.g. The Hips, Shoulders, Knee
There are six types of synovial joints:-
Shoulder and Hip
Knees and Elbows
Neck
Hand/Wrist
Thumbs
Wrist
Movement At Synovial Joints
There are six types of movements that can occur at the joints
- Extension – Straightening or extending a limb e.g. an arm can be extended at the elbow
- Flexion – Bending your limbs e.g. The leg can be bent at the knee
- Abduction – Moving a limb away from the centre line of the body e.g. the leg can be move away from the body at the hip
- Adduction – Moving a limb towards the centre line of the body e.g. The arms can be moved towards the body at the shoulder
- Rotation – Turning or rotating of a limb or body part e.g. the head can be rotated at the neck
- Circumduction – The ability of a limb to move in full circles e.g. the arms can move in circles at the shoulder
Ball and socket joint:
Extension, flexion, abduction, adduction, rotation, circumduction
Hinge joint:
Extension, flexion
Pivot joint:
Rotation
The Effects of Exercise on the Skeletal System
- Weight bearing activities make the bones stronger – Less likely to break a bone
- Exercise increases mineral content e.g. calcium – makes bones stronger and harder
- Exercise increases the thickness of cartilage at the end of bones and increases the production of synovial fluids – this makes the joint stronger and less likely to suffer from joint injury
