Bones

Bone

living tissue capable of changing its structure as the result of stresses to which it is subjected

• consists of cells, fibers and matrix

• calcification hardens surface

• protective function

• lever storage and protection

forms

• compact

• cancellous

Compact bone

solid mass

Cancellous bone

branching network of trabeculae

Long bones

found in limbs (humerus, femur, metacarpals/tarsals. phalanges)

tubular shaft, diaphysis, and ephyisis

growth

• epiphysis separates by epiphyseal cartilage

• metaphysis = lies between diaphysis

• central marrow cavity with bone marrow

• periosteum = connective tissue sheath covering the outer compact bone

Short bones

found in hand and foot

• cuboidal in shape

composed

• cancellous bone surrounded by thin layer of compact bone

• periosteum and hyaline cartilage

Flat bone

found in vault of skull

• thin inner and outer layers of compact bone,

• tables separated by cancellous bone (diploe)

Irregular bones

unassigned groups

• thin shell of compact bone with interior made of cancellous bone

Sesamoid bone

small nodules of bones found on certain tendons

EX: Patella

Surface markings of bones

irregularities in bones that first appear at puberty

some are large with special names

Bone marrow

occupies marrow cavity in long and short bones and cancellous tissue in flat and irregular bones

starts as red at birth = becomes yellow at the age of 7

periosteum

thick layer of fibrous tissue has abundant vascular supply and osteogenic deep cells

provides rich nerve supply = highly senstiive

Bone development

menbranous and endochondral

• developed directly from connective tissue membrane

• cartilaginous model is laid down and later replaced by bone.

Membranous method

bones of the vault of skull

• serves to protect underlying developing brain

Endochondral method

long bones of limbs are developed in a slow process until 18-20th year

• diaphysis (found in shaft of bone)

• epiphysis (ends of bone)