Skeletal system

• how many bones are in the body 


  206
• the bone tissue stores calcium
• Babies have 100 more bones than adults
• The skeletal system is composed of 206 bones consisting of a central axis to which the appendicular skeleton is attached
• the axial skeleton consists of the 80 bones along the central axis of the human body used mainly for structure and protection
• the appendicular skeleton is composed of 126 bones in the human body mainly used for movement
• The axial skeleton consists of the vertebrae, rib cage and the skull
• the appendicular skeleton consists of the upper and lower limbs
• bones in the axial skeleton


  cranium, sternum, ribs, cervical vertebrae, thoracic vertebrae, lumbar vertebrae, sacrum, coccyx
• bones in the appendicular skeleton

  scapula, clavicle, humerus, radius, ulna, carpals, metacarpals, phalanges, ilium, ischium, pubis, femur, patella, tibia, fibula, tarsals, talus, metatarsals
• what are the functions of the skeleton


  • protection
  • support
  • blood cell production
  • shape / posture
  • mineral storage
• Protection


  • the hard nature of the bone means that the skeleton can protect the more delicate parts of the body
  • cranium protects the soft tissue of the brain
• support


  • holds your vital organs in place when playing sport.
  • vertebrae supports the head
• shape

  • gives shape to the body and makes you tall or short.
  • without the skeleton, the body would be shapeless
• movement

  • the skeleton is jointed to allow us to move when the muscles attached to them contract
  • walking, jogging, sprinting
• blood cell production


  • red and white blood cells are made in red bone marrow which is found at the ends of the femur and humerus and in the ribs, sternum, pelvis and vertebrae
  • femur contains bone marrow
• mineral storage


  • blood tissues store several minerals, including calcium.
  • when required, bone releases minerals into the blood, facilitating the balance of minerals in the body.
  • it also stores fat to be used as energy if required in the form of yellow bone marrow
• types of bones


  • long
  • short
  • flat
  • irregular
  • sesamoid
• long bones


  generally longer in length than width. e.g. femur, phalanges
• short bones


  bones that are short and fat in shape. e.g. tarsals, carpals
• flat bones


  bones that are flat and usually for protection or attachment. e.g. sternum, ilium
• irregular bones


  random bones that do not fit into another category e.g. vertebrae
• sesamoid


  similar to short bones but they are floating between tendons. e.g. patella
• bone functions


  • long - movement and blood cell production
  • short - support
  • flat - protection and movement
  • irregular - support, movement and protection
  • sesamoid - movement
• how long bones carry out their function


  muscles attach to the ends of long bones with the length of the bone making it an ideal lever to facilitate movement.

  both yellow and red bone marrow is produced in the marrow cavity of long bones. this is vital for the production of blood cells
• how short bones carry out their function


  short bones give support and stability because they are as wide as they are long. they act as small 'jigsaw' pieces that bridge between gapes between bones that facilitate movement. short bones are not involved in movement.
• how flat bones carry out their function


  flat bones have a large, flat area which can protect vital organs beneath. the large flat bones also provide extensive areas for muscular attachment
• how irregular bones carry out their function


  irregular bones form support for the pharynx and larynx. the bony prominences make ideal attachment sites for muscles. the vertebrae protect the spinal chord
• how sesamoid bones carry out their function


  sesamoid bones are found in joints where they form a smooth surface for tendons to slide over. this increases the force that the tendon can transmit
• what are the 3 types of joint


  • freely moveable (synovial)
  • slightly moveable
  • fixed
• what are the 6 types of synovial joint


  • ball & socket
  • condyloid
  • saddle
  • hinge
  • pivot
  • plane
• articular cartilage


  hard and glossy smooth tissue which coats the end of bones where they meet and enables them to move without friction
• ligaments 


  strong and slightly elastic tissue which holds 2 bones in place and more stability and aid motion
• synovial membrane


  layer which lines the synovial joint and produces the synovial fluid
• synovial fluid


  thick, white fluid which helps lubricate the joint
• meniscus


  small pads of tissue which sit between the joint and act as a shock absorber to cushion impact
• fat pads


  shock absorber which fills the spaces between the joints
• bursae


  small sacks of fluid that work as a cushion and gliding surface to prevent the skin rubbing on the bones
• joint capsule


  protective layer around the end of the joint
• types of joint

  1. fixed
  2. slightly movable (cartilaginous)
  3. freely movable (synovial)