The Skeletal System

Functions of the Skeleton
1. Support
  1. Human Skeleton is an upright frame- gives human body it's characteristic shape.
  2. Arranged to provide means of support- body and its component parts.
2. Protection
  1. Bones form protective containers for internal organs.
    1. E.g. *Flat bones of skull surround and protect the brain. * Bones of thorax protect the heart and lungs. *Pelvic Girdle protects the reproductive organs.
3. Movement
  1. Muscles attach to bones, enabling them to act as levers.
    1. Allows a range of movement at joints and provides mobility.
4. Development of blood cells
  1. Many bones in human skeleton are hollow, with cavities containing bone marrow.
    1. In adults, bone marrow is the red blood cell production site.
5. Mineral reservoir
  1. Approximately 97% of mineral calcium is stored in bones.
    1. If store is diminished, e.g. pregnancy, menopause or poor diet, bones become more brittle- Can lead to Osteoporosis (occurs when bone mass diminishes). Sufferers more prone to suffer breaks or fractures as their bones become weaker.
Types of Joint + Cartilage, Tendons and Ligaments
1. Types of Joint
  1. A joint is formed where two or more bones meet. Three groups of joints are: *Fibrous Joints *Cartilaginous Joints *Synovial Joints
    1. Fibrous Joints
      1. Found where two bones dovetail together, bound together with thin bands of fibrous tissue called STRUCTURES.
      2. DO NOT permit any movement-also known as fixed or immovable joints.
      3. E.g. Fibrous joints are found between the bones of the skull (cranium).
    2. Cartilaginous Joints
      1. Permit limited movement -also known as slightly moveable joints.
      2. Formed where two bones are connected by a pad of FIBROCARTILAGE- acts as shock absorber.
        Also surrounded by fibrous connective tissue- holds joint in place.
      3. E.g. Between vertebrae and between pubic bones (pubic symphysis).
    3. Synovial Joints
      1. Formed where two or more bones meet.
      2. Freely moveable and are named according to movements they permit.
        Movements dependent on shape and size of bones which form them, as well as muscle tone.
        There are a total of about 70 synovial joints in the body.
      3. Ends of bones which form these joints are covered with fibrous connective tissue called ARTICULAR/HYALINE CARTILAGE.
        Helps reduce friction between bones.
      4. Contained in connective tissue which enables free movement and nourishes cartilage cells.
      5. Bones of a synovial joint do not meet but instead for a synovial cavity, lined with synovial membrane, except over ends of bone. Entire cavity (including ends of bones) enclosed within a FIBROUS CAPSULE- protects joint.
2. Cartilage, Tendons and Ligaments
  1. Tendons
    1. Strong, fibrous bands of connective tissue which ATTACH MUSCLES TO BONES.
    2. Almost inelastic.
    3. Contraction of a muscle through a tendon causes movement of a bone joint. E.g. Achilles tendon which attaches calf muscle (gastrocnemius) to heel of foot (calcaneum).
    4. Flattened sheet of tendinous fibres= an APONEUROSIS E.g. palmar aponeurosis on palm of hand, and inguinal ligament in the groin.
  2. Ligaments
    1. Bands of strong, fibrous connective tissue which holds bones together across joints and stretch to allow movement.
  3. Cartilage
    1. Type of firm connective tissue with dense network of collagen and elastin fibres.
    2. It's unusual as contains NO BLOOD VESSELS or NERVES.
    3. Hyaline cartilage- particular cartilage that covers end of long bones and also forms the nose, larynx, trachea and bronchi.
    4. *Fibrocartilage provides strength and rigidity and is located in intervertebral discs. *Elastin cartilage provides strength and support and helps maintain shape of internal organs.

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The Skeletal System

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	Created by Molly Heathcote about 8 years ago

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