1. Skeletal System Students Learn To: Major bones involved in movement
Structure and function of synovial joints
Joint actions eg extension and flexion
Students Learn About:
Identify the location and type of major bones involved in movement eg long bones articulate at hinge joints for flexion and extension

2. Skeletal System - Introduction
The adult human skeleton has 206 bones. They range in shape and size, a feature that allows them to perform specialised functions.
Functions of bones:
It supports the organs and tissues of the body. Without this support they would collapse under their own weight.
It provides protection for internal organs. For example, the cranium protects the brain; the thorax protects the heart and lungs
It provides a base for the attachment of muscles and so allows movement with the bones acting as levers.
The bones are a source of supply of blood cells and a store for minerals required for the body to function. For example, red and white blood cells are produced in the bone marrow, which is found in the middle of bones.

3. Skeletal System
An anatomical reference system called directional terms is used to identify the location of bones.
The starting point assumes that the body is in the Anatomical position; that is, a reference position where the subject is standing erect, facing front on and with palms facing forward.
This enables us to locate a bone in reference to how it is relative to another part of the body.

4. Skeletal System
Axial skeleton - consists of the bones of the skull, the thoracic/rib cage and the vertebrae column
Appendicular skeleton - consists of the bones of the upper and lower limbs and the bony girdles that support them on the body trunk.
Orange – Axial
Blue - Appendicular

5. Types of Bone There are five (5) types of bone: Long Short Flat
Irregular
Sesamoid.
Long Bones - are longer than they are wide, the function as levers.
Examples: humerus, femur, radius, tibia, ulna and phalanges.
Short Bones - have a short axis and are found in small spaces such as the wrist. They serve to transfer forces.
Examples: bones in the wrist (carpals) and ankle bones (tarsals)
Flat Bones - have a broad surface and serve as places of attachment for muscles and to protect vital organs.
Examples: scapula, cranial bones, sternum and ribs

6. Long Bones

7. Short Bones

8. Flat Bones

9. Types of Bone
Irregular Bones - do not fall into any category due to their non-uniform shape. Primarily consist of cancellous bone, with a thin outer layer of compact bone.
Example: vertebrae
Sesamoid Bones - usually short and irregular bones, imbedded in a tendon where it passes over a joint which serves to protect the tendon.
Examples: the patella

10. Irregular Bones

11. Sesamoid Bone

12. Types of Joints
Joints occur where one or more bones meet. They can be fixed, such as the rib cage, or they can be more moveable such as in the elbow.
Are classified according to their degree or movement, such as:
Fibrous or immovable
Cartilaginous or slightly moveable
Synovial or freely moveable
Fibrous joints occur where bone ends are joined by strong, short bands or fibrous tissue such as in the skull.
This type of joint does not allow any movement to occur.
Cartilaginous joints is where the bones are separated by a disc or plate made up of tough fibrous cartilage.
For example the joints of the vertebrae or spine are separated by this tissue thus causing limited movement.
Synovial joints allow for a range of movement.
These include hinge joints (knee and elbow) and ball and socket joints (hip and shoulders).
Synovial joints are made possible with the use of tendons, ligaments, cartilage, and synovial fluid.

13. Structure of Synovial Joints
There are 6 different types of synovial joints:
Plane (Inter-Tarsal joints) – allows limited gliding movements
Hinge (Elbow) – allows movements along one axis for flexion or extension
Pivot (C1 to C2 vertebral joint) – allows rotational movements and some bending
Ellipsoid/Condyloid (Radius to carpal joint – wrist) – allows movement in two planes, allowing flexion, extension, adduction, abduction, and circumduction.
Saddle (base of the thumb) – allows same movements as the condyloid but with no axial rotation.
Ball-and-socket (Hip) – allows movement through three planes (flexion, extension; abduction, adduction; rotation) and is the most mobile of the synovial joints
Diagram next slide

14. Synovial Joints

15. Structure of Synovial Joints
The internal structure of each of these joints, though slightly different in the number of ligaments, tendons, and whether they have menisci or other specialised attributes, is roughly the same.
Each joint has:
Articular cartilage – which helps allow for smooth pain free movement
A synovial membrane and joint cavity – which hold in the synovial fluid which provides the lubricant for the joint to move smoothly and pain free.
On top of this layer there are joint ligaments that hold the 2 bones involved in the joint together and help to restrict movement of that joint to how the synovial joint type moves.
Although not part of the skeletal system or technically the structure of a joint, muscle tendons are the next layer around joints and may have a bursa (pad for cushioning) between them and the joint to prevent wear and tear. Tendons join muscle to bone and stretch across joints to allow the joint to move.
Some joints, such as the knee, also have a meniscus in them. This is essentially an extra layer of cartilage that aims to provide cushioning within the joint. It is normally found in joints that bear large loads, such as the knee.

16. Structure of Synovial Joints - Knee

17. Overview of Skeletal Bones – Anterior View

18. Overview of Skeletal Bones – Posterior View

19. Vertebral Column

20. Directional Terms Superior Inferior Anterior Posterior Medial Lateral
towards the head; for example, the chest is superior to the hips
Inferior
towards the feet; for example, the foot is inferior to the leg
Anterior
towards the front; for example, the breast is on the anterior chest wall
Posterior
towards the back; for example, the backbone is posterior to the heart
Medial
towards the midline of the body; for example, the big toe is on the medial side of the foot
Lateral
towards the side of the body; for example, the little toe is on the lateral side of the foot
Proximal
towards the body’s mass; for example, the shoulder is proximal to the elbow
Distal
away from the body’s mass; for example, the elbow is distal to the shoulder.

21. Directional Terms