SKELETAL SYSTEM BONE TISSUE

-bones -cartilages -ligaments -tendons

study of bone structure and tx of bone disorders

• support • protection • assistance in movement • mineral homeostasis • blood cell protection • triglyceride storage

new bone

tissue in which new blood cells are formed -INFANTS: in medullary cavities of diaphysis and all areas of spongy bone -ADULTS: between trabecular and spongy bones in flat bones, skull, sternum, ribs, hips, etc.

crystals form, combining with other ions and these mineral salts are deposited in a framework of collagen fibres - INITIATED BY OSTEOBLASTS

calcium phosphate (most abundant) and calcium hydroxide

-80% of bones -few spaces -found beneath periosteum -protection, support, resists compression

-20% of bones -does not contain osteons -located in interior of bone -trabecular

• initial bone formation • growth of bone during development • remodelling of bone • bone repair

loosely organized, mainly mesodermal embryonic tissue, develops into connective and skeletal tissues

INITIAL BONE FORMATION -week 8 of embryo development (flat bones like cranial, rib clavicle) -bone forms directly within mesenchyme -mesenchyme cells to cartilage to bone

INITIAL BONE FORMATION -2nd month of development (long bones like tibia, femur, humerous) -forms from hyaline cartilage which develops from mesenchyme cartilage

• INTERSTITIAL GROWTH OF CARTILAGE - on epiphyseal side of the epiphyseal plate • REPLACEMENT OF CARTILAGE - on diaphysial side through endochondral ossification

• minerals • vitamins • hormones

• open (compound) • comminuted • greenstick • impacted • pott • colles

LONG BONE STRUCTURE -tube or shaft through long bone -surrounds medullary cavity

LONG BONE STRUCTURE -bone ends -thin layer of hyaline cartilage covers joint surface

LONG BONE STRUCTURE -double layer membrane covering external surface of bone

LONG BONE STRUCTURE -internal bone covering

-found in periosteum and endosteum -in growing bones they are squamous cells and differentiate into osteoblasts

-bone forming cells

-mature bone cells that occupy spaces (lacunae) that conform to their shape -monitor and maintain bone matrix -communicate info to cells about bone remodelling

-giant multinucleate cells located at sites of bone resorption -increase SA for enzymatically degrading the bones and seal off area from surrounding matrix -dissolve bone -concentrated in endosteum