BONES AND JOINTS

Basic Anatomy

The Skeleton

• 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.

SKELETAL FUNCTION

• 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

• 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

• 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.

Joint Types1: Ball and Socket

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

                 

Joint Types2: Hinge

• 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

Joint Types3: Pivot

• 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

Joint Types4: Gliding

• 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

                  

  

Joint movement: Extension

• 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

Joint movement: Abduction

• 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

Joint movement: Adduction

• When a joint moves towards the vertical centreline of the body, it is known as adduction.

• This movement occurs when the arm is lowered

Joint movement: Rotation

• 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

Joint movement: General For all joints except the knee and

elbow Forward movement

is flexionRearward movement is extension