The Skeletal The Skeletal SystemSystem

Supports the body

Protects soft organs

Allows movement due to attached skeletal muscles

Stores minerals and fats

Blood cell formation

The Skeletal SystemThe Skeletal SystemParts of the skeletal systemParts of the skeletal system– Bones (skeleton)Bones (skeleton)– JointsJoints– CartilagesCartilages– LigamentsLigaments

Two subdivisions of Two subdivisions of the skeletonthe skeleton– Axial skeletonAxial skeleton

skull, spine, ribs skull, spine, ribs– Appendicular skeletonAppendicular skeleton

shoulders, arms shoulders, arms hips, legs hips, legs

Bones of the Bones of the Human BodyHuman Body

The adult skeleton The adult skeleton has 206 boneshas 206 bones

Two basic types of Two basic types of bone tissuebone tissue

– Compact boneCompact bone

– Spongy boneSpongy bone

Classification of Bones by shapeClassification of Bones by shape

Long bonesLong bones– Typically longer than Typically longer than

they are widethey are wide– Have a shaft with Have a shaft with

heads at both endsheads at both ends– Contain mostly Contain mostly

compact bonecompact bone– ExampleExample::

FemurFemur

HumerusHumerus

Shaft

Classification of Bones by ShapeClassification of Bones by ShapeShort bonesShort bones

– Generally cube-shapeGenerally cube-shape– Contain mostly Contain mostly

spongy bonespongy bone– ExampleExample::

CarpalsCarpals

TarsalsTarsals

Classification of Bones by ShapeClassification of Bones by ShapeFlat bonesFlat bones

– Thin, flattened, and Thin, flattened, and usually curvedusually curved

– Two thin layers of Two thin layers of compact bone compact bone surround a layer of surround a layer of spongy bonespongy bone

– ExampleExample: : SkullSkullRibsRibsSternumSternum

Classification of Bones by ShapeClassification of Bones by Shape

Irregular bonesIrregular bones– Irregular shapeIrregular shape– Do not fit into other Do not fit into other

bone classification bone classification categoriescategories

– ExampleExample: :

Vertebrae Vertebrae

Hip bonesHip bones

Anatomy of a Long BoneAnatomy of a Long Bone

DiaphysisDiaphysis– ShaftShaft– Composed of compact Composed of compact

bonebone

EpiphysisEpiphysis – Ends of the boneEnds of the bone– Composed mostly of Composed mostly of

spongy bonespongy bone

Anatomy of a Long BoneAnatomy of a Long Bone

PeriosteumPeriosteum– Outside covering of Outside covering of

the diaphysis (shaft)the diaphysis (shaft)– Fibrous connective Fibrous connective

tissue membranetissue membrane

Cartilage = Connective TissueCartilage = Connective Tissue

CartilageCartilage– Covers the external surface of long bonesCovers the external surface of long bones– Made of “Made of “hyaline cartilagehyaline cartilage””– Decreases friction at joint surfacesDecreases friction at joint surfaces

When you’re When you’re growing….growing….

Epiphyseal plateEpiphyseal plate– Flat plate of hyaline Flat plate of hyaline

cartilage seen in cartilage seen in young, growing bone young, growing bone (a.k.a. = growth plate)(a.k.a. = growth plate)

Epiphyseal lineEpiphyseal line– Remnant of the Remnant of the

epiphyseal plateepiphyseal plate– Seen in adult bonesSeen in adult bones

Anatomy of a Long BoneAnatomy of a Long BoneMedullary cavityMedullary cavity

– Cavity inside of the Cavity inside of the shaftshaft

– Contains yellow Contains yellow marrow (mostly fat) in marrow (mostly fat) in adults. With severe adults. With severe blood loss, can be blood loss, can be converted to red converted to red marrowmarrow

– Contains red marrow Contains red marrow (for blood cell (for blood cell formation) in infantsformation) in infants