Divisions of the skeleton

• What are the 2 divisions of the skeleton?

  1. Axial
  2. Appendicular
• The axial skeleton is made up of the skull, vertebral column, ribcage, sternum, hyoid bone. They also protect the vital organs.
• The skull is part of the superior part of the body, which contains the cranium and facial bones.
• The cranium encloses the brain, which allows the facial bones to attach.
• The facial bones protect and support facial organs.
• The verterbral column is part of the axial skeleton, whcih allows the person to stand up right.

  • contains ligaments and muscle movements
  • supports the head
  • have 4 divisions: cervical, lumbar, thoracic, saccrum
• The ribcage contains the sternum and ribs. This is to protect the front.

  • ribs contain 12 on each side and joins onto the sternum, which are the top 10 ribs that attach to the cartilage.
• The appendicular skeleton is the skeleton of the upper and lower limbs.
• The structure of the limbs contain:

  • single, large, long bone, which is the humerus and femur
  • has 2 distal bones, which are long and thinner
• The ulna and radius are superior, mobile and weight bearing.
• The tibia and fibula are inferior, immobile and non-weight bearing.
• Bipedalism is the ability to walk on two legs using 2 limbs, which are the upper limb and lower limb.
• The upper limb in bipedalism does not need stability because it is adapted to manipulated objects and precise movements.
• The lower limb needs more stability due to its role as a support base when walking or running.
• The hands do not need stability because it is not involved with locomotion.

  Structure of hands:

  • Carpals (8) - short bones
  • Metacarpals (5) - long bones
  • Phalanges (14) - 2 in thumb
• The humerus is lighter and is not responsible for long strides and for not taking weight as it is not stable, therefore less articulation.
• The femur is more deeper in articulation and is for long strides and more stable.
• Pronation and supernation occur when we move our forearms and wrists. They have a wide surface area to move the wrist, which allows for rotation.
• Supination occurs when the palm faces upwards while pronation occurs when the palm faces downwards.
• The ankle joint is stable, the tibia is robust (weight bearing).
• The limbs attach to the axial skeleton by the pectoral girdle, which contains the clavicle and scapula.
• The clavicle stabilises for the shoulder blade as it keeps it in the right position.
• The Scapula is free moving and does the muscle attachment and joins the upper limb.
• The lower limb also attaches using the pelvic girdle, containing the hip bone, saccrum and are weight bearing.
• The hip bone contains:

  • illium
  • pubis
  • ischium

  And fuse together to form the hip bone.
• Female pelvis is bigger because they have potential to make birth and maximise their space for that.

  • more circular
  • outlet is more open