Work Sheet 4.1 – Structure and Function of the Skeletal System
The skeletal system consists of 206 bones which are classified into 4 groups:
• Long e.g. femur
• Short e.g. phalanges
• Flat e.g. pelvis
• Irregular e.g. vertebrae
The skeleton has 5 major functions which are:
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Shape – forms a frame under the skin which determines body height, width, etc.
Support – provides a rigid framework for the body to be able to function
Protection – of delicate internal, vital organs such as the heart, lungs, etc
Movement – muscles are attached to bones which pull on them to produce movement
Blood Production – bone marrow produces blood cells
Work Sheet 4.2 – Joints
When 2 bones meet each other they form a joint. The types of joints are classified into 3
groups:
• Fixed e.g. in the skull
• Slightly moveable e.g. vertebrae
• Freely moveable or synovial joints e.g. shoulder, hip, knee, elbow
Structure of Synovial Joint:
The structure of a synovial joint consists of:
• Joint capsule - provides support for the synovial membrane
• Synovial membrane - secrets synovial fluid which lubricates the joint
• Synovial fluid - allows friction free movement of the joint
• Articular cartilage - covers the end of bones and reduces friction at the joint
• Ligaments - stabilise the joint so as to prevent excessive movement.
There are six types of synovial joints:
Ball and socket joint – found in the shoulder and hips
Hinge joint – found in the elbow and the knee
Gliding joint – found in the carpal bones in the hand
Pivot joint – found in the neck
Saddle joint – found in the thumbs
Condyloid joint – found in the wrist
Work Sheet 4.3 – Movement
There are a number of different types of joint movement:
Flexion – bending at the joint e.g. drawing the leg back before kicking a ball
Extension – straightening the joint e.g. straightening the leg to kick a ball
Adduction – movement towards the body’s central line e.g. arm pull in a breast stroke
Abduction – movement away from the body’s central line e.g. legs during a star jump
Rotation – a turning movement around an imaginary line e.g. bowling in cricket