• The average human adult skeleton has 206 bones joined to ligaments and tendons
• Forms a protective and supportive framework for the attached muscles and the soft tissues which underlie it.
• Minor differences between male and female skeletons: men's bones tend to be larger and heavier than corresponding women's bones, and a woman's pelvic cavity is wider to accommodate childbirth.

• The skeleton plays an important part in movement by providing a series of independently movable levers, which the muscles can pull to move different parts of the body
• It supports and protects the internal body organs
• It is an efficient factory which produces red blood cells from the bone marrow of certain bones and white cells from the marrow of other bones
• The bones are also a storehouse for minerals calcium, for example - which can be supplied to other parts of the body

• Joints permit bodily movement and are held together by fibres called "ligaments".
• Some joints, like those in the skull, allow no movement.
• Others may permit only limited movement: for example the joints in the spine allow some movement in several directions.
• Moveable joints are continuously lubricated to prevent friction. These joints have a variable range of movement, and these are called
"synovial" joints.

• Joints are sturdy enough to hold the skeleton together while permitting a range of motions.
• Joints are lubricated by "synovial" fluid.
• The ends of these joints are coated with articular
(or hyaline) cartilage, which reduces friction and cushions against jolts.
• Between the bones, in a narrow space, is the joint
"cavity," which gives us freedom of movement.
• Ligaments then bind these bones to prevent dislocations and limit the joint's movements.

• The greatest range of joint movement is provided by a "balland- socket" joint, in which the spherical head of one bone lodges in the spherical cavity of another

• The simplest type of joint is the "hinge," as found in the elbows and the joints of the fingers and toes.
• Hinge joints allow movement in only one direction.
Elbow

• A pivot joint allows two bones to move in a rotational motion by twisting against each other
• The radio-ulnar joint in the elbow, or atlas/axis in the neck do this

• Gliding" joints permit a wide range of mostly sideways movements
- as well as movements in one direction
• The bones in the wrists and ankles slide against each other in a gliding motion
• The spine is a series of gliding joints

• When two bones move away from each other, the action is known as
EXTENSION
• This would occur for example with straightening of the elbow or knee

• When a joint moves away from the vertical centreline of the body, it is known as abduction.
• This movement occurs when the arm is raised to one side

• When a joint moves towards the vertical centreline of the body, it is known as adduction.
• This movement occurs when the arm is lowered

• This occurs when a bone rotates, either in a socket or relative to another bone.
• It can occur at ball & socket or gliding type joints
Lowering (blue arrow) is internal rotation.
Raising is external

Forward movement is flexion
Rearward movement is extension