skeletal system and bone development

bone

made of osseous tissue, Functions: support and protection / body movement / storage of inorganic materials / blood cell formation in bone marrow (hematopoiesis)

about _ bones are in an adult 206; this number depends on bone fusion as a child

axial division

• head, neck, trunk

• includes skull and hyoid bone (tongue attaches to this bone BUT does not join any other bone)

• includes vertebral column

• includes thoracic cage (12 pairs of ribs)

appendicular division

limbs & bones that connect to
pectoral girdle (shoulders) & upper limbs
pelvic girdle (hips) & lower limbs

provide stability and support

long bone

- typically longer than they are wide
- have a shaft with heads at both ends
- contain mostly compact bone

bone anatomy primarily based on this type of bone

ex. femur, humerus

short bone

- typically cube-shaped
- contain mostly spongy bone

ex. carpals (wrist), tarsals (ankles)

flat bone

- thin and flattened BUT usually curved
- thin layers of compact bone around a layer of spongy bone

ex. skull, ribs, sternum

irregular bone

irregular shape, do not fit into other bone classification categories

ex. vertebrae, hip

sesamoid bone

enshrouded (completely within) by a tendon

ex. kneecap/patella (at a joint for stability)

ossification

the process of forming bones from hyaline cartilage and fibrous membrane (which the human skeleton starts as)

two types: intramembranous (flat bones and skull) and endochondral (all others)

by age ____, the skeleton is completely hardened and done developing

25

epiphyseal disk

growth plate

- band of cartilage found between epiphysis and diaphysis
- typically found in long bones
- increase bone length as cells ossify

osteoblasts

build new bone from cartilage

osteocysts

maintain the matrix of healthy bone

osteoclast

dissolve bone tissue to release minerals - leads to process of resorption (minerals going to blood for transport)