1) Skeleton is the supporting structure which:
- enable movement when the bones interact with the skeletal muscles
- give shape & give mechanical support for the body
- protect the internal organs. (eg: the skull protects the brain, the ribcage protects the lungs & heart)
- provide firm base for attachment of skeletal muscles.
- produces blood cells - eg Red Blood Cells are formed in the bone marrow of the long bones.
- stores minerals, eg: calcium & phosphate.
2) 3 types of skeletons:
- Hydrostatic skeleton - consists of internal fluid within a confined spaces of the body & is kept under pressure surrounded by muscles. eg: earthworm.
- Exoskeleton - non-living structure (eg: cuticle) that covers the surface of the body. It support the internal organs, protect internal structure from damages. eg: grasshopper.
- Endoskeleton - consists of a rigid framework of bones & cartilage which muscles are attached. It maintains body shape, support soft body tissues, protecting internal organ from injury.
3) The Human Skeletal System.
a) Is divided into 2:
- i) Axial skeleton: the skull, the vertebral column, ribs & sternum (ribcage)
- ii) Appendicular skeleton: pectoral girdle, pelvic girdle, bones of the limb
- 1) Centrum (solid body)
- 2) Neural canal
- 3) several neural processes
- Function of the structure of a vertebra:
1) Neural spine - provide surface for attachment of muscles & ligaments.
2) Transverse process - same as above
3) Neural arch - protects the spinal cord.
4) Centrum - provides support, absorb shocks, resists compression.
5) Neural canal - provides the passage for spinal cord.
6) articular processes/facets - provides surfaces which articulates with the next vertebra/bones.
4) Axial skeleton:
- consists of the skull, the vertebral column, ribs, sternum.
- i) Skull
a) consists of cranial bones (cranium) & facial bones.
b) functions:
1) the cranium enclose & protect the brain.
2) the facial bones protect & support the entrance of digestive & respiratory system. - ii) The vertebral column:
a) consists of 33 small vertebrae.
b) divided into 5 parts :
1) Cervical vertebrae (neck, 7 vertebrae, C1-C7, C1 is known as atlas, C2 is known as axis)
2) Thoracic vertebrae (thorax & chest region, 12 vertebrae, T1-T12)
3) Lumbar vertebrae (lower back region, 5 vertebrae, L1-L5)
4) Sacrum (lower back region, 5 sacral vertebrae, fused, S1-S5)
5) Coccyx (tailbone, 4 fused caudal vertebrae)
c) Intervertebral disc is located in between the vertebrae.
1) made up of cartilage.
2) functions: act as cushion to absorb shocks when moving, to reduce friction btw
vertebrae.
d) Function of vertebral column:
1) support the head/skull & body
2) encloses & protect the spinal cord
3) provide base for attachment of muscles to the back
4) ... Question: why the vertebral column is made up of 33 vertebrae, not one long bone? - iii) the ribcage: (ribs & sternum)
a) 12 pairs of ribs, articulate with the thoracic vertebrae at the back & join to the sternum in the front portion.
b) ribs are flattened, curved bones.
c) functions:
1) protects the heart & lungs
2) role in breathing.
d) sternum is a flatenned, kite-shape bone, located at the anterior thoracic wall.
e)Main characteristic of vertebrae.
1) Cervical vertebra - has a pair of vertebrarterial canals, has thin centrum (plural: centra)
2) Thoracic vertebra - has long & backward/downward pointing neural spine, fairy large centrum, heart-shaped centrum.
3) Lumbar vertebra - thick & big centrum, short & broad neural spine, large & broad/flat transverse process.
4) refer pg 4 of yr notes.
click here - to view animated human skeletal system
.... to be continued ....
