The skeletal system

Structure and function of bone

Organization of the skeleton

Joints

Functions of bone (skeleton)

Support and protection

Blood cell formation

Mineral storage (calcium especially)

Site for muscle attachmentbody movement

Bones classified by shape: long, short, flat, irregular, round

Bone enclosed in periosteum, which is continuouswith tendons and ligamentsblood vessels in periosteum

Epiphysis- endsspongy bone contains red marrowcompact bone, articular cartilage

Diaphysis- middlecompact bonemedullary cavity- contains yellow marrow (fat)lined with endosteum (squamous epithelium)

Compact boneosteocytes within lacunaearranged in concentric circles called lamellae

This surround a central canal; complex is calledHaversian system

Canaliculi connect osteocytes to central canal andto each other

Prenatal developmentskeleton is mostly cartilaginous

Cartilage cells and then osteoblasts start todeposit minerals

Cartilaginous disk (epiphyseal disk) remainsin epiphysis

Cells eventually stop dividing

Adults continually break down and build up bone

Osteoclasts remove damaged cells and releasecalcium into blood

Osteoblasts remove calcium from blood and buildnew matrix. They become trappedosteoclasts

Types of bone breaks

Simple- skin is not piercedCompound- skin is piercedComplete- bone is broken in halfPartial- broken lengthwise but not into two

partsGreenstick- incomplete break on outer arcComminuted- broken into several piecesSpiral- twisted

Fracture repair

Hematoma- blood clot in space between edgesof break

Fibrocartilage callus- begins tissue repair

Bony callus- osteoblasts produce trabeculae(structural support) of spongy bone andreplace fibrocartilage

Remodeling- osteoblasts build new compact bone,osteoclasts build new medullary cavity

Axial skeletonskull (cranium and facial bones) hyoid bone (anchors tongue and muscles

associated with swallowing) vertebral column (vertebrae and disks) thoracic cage (ribs and sternum)

Appendicular skeletonpectoral girdle (clavicles and scapulae)upper limbs (arms)pelvic girdle (coxal bones, sacrum, coccyx)lower limbs (legs)

posterior viewp. 135

Axial skeleton supports and protects organsof head, neck and trunk

Appendicular skeleton- bones of limbs and bones that anchor them to the axialskeleton

Articulation- where joints are formed

22 bones in skull6 in middle ears1 hyoid bone26 in vertebral column25 in thoracic cage

4 in pectoral girdle60 in upper limbs60 in lower limbs2 in pelvic girdle

206 bones in all

The skull

8 sutured bones in craniumFacial bones: 13 sutured bones, 1 mandible

Craniumencases brainattachments for musclessinuses

Allows forgrowth

Vertebral column

7 cervial vertebrae12 thoracic5 lumbar1 sacrum (5 fused 1 coccyx (4 fused)

Vertebrae vary in size and morphology

Thoracic cageribsthoracic vertebraesternumcostal cartilages

True ribs are directly attached to the sternum(first seven pairs)Three false ribs are joined to the 7th ribTwo pairs of floating ribs

Clavicles and scapulae

Help brace shouldersAttachment sites for muscles

Bones of upper limb

Humerus (upper arm)Radius; ulnaCarpals, metacarpals, phalanges

Bones of lower limb

FemurPatellaTibia, fibulaTarsals, metatarslas, phalanges