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Parts of the skeletal system

Bones (skeleton)JointsCartilagesLigaments

Two divisions of the skeletal system

Axial skeletonAppendicular skeleton

Five primary Functions of the Skeletal System

SupportStorage of Minerals (calcium) and Lipids (yellow marrow)Blood Cell Production (red marrow)ProtectionLeverage and Motion

Adult skeleton has \___ bones

206

Two basic types of bone tissue

Compact boneSpongy bone

Compact Bone

Hard

Spongy Bone

Bone tissue that consists of an open network of struts and plates that resembles latticeworkInner layer of most bones and ends of epiphysis of long bones

Bones are classified by

ShapeInternal tissue organizationBone markings (surface features

marks)

Six bone shapes

Flat bonesLong bonesIrregular bonesSutural bonesSesamoid bonesShort bones

Sutural Bones

Small

Irregular Bones

Have complex shapesEx: spinal vertebrae and pelvic bones

Short bones

Small and thickEx: ankle and wrist bones

Flat bones

Thin with parallel surfaces

Flat bones are found in \___

skull

Long bones

Long and thin

Long bones are found in \___

arms

Sesamoid bones

Small and flat

Sesamoid bones develop inside \___

tendons near joints of knees

Depressions or grooves are found along

bone surface

Elevations or projections

Where tendons and ligaments attachAt articulations with other bones

Tunnels

Where blood and nerves enter bone

Structure of a long bone

DiaphysisEpiphysisMetaphysis

Diaphysis

The shaftA heavy wall of compact bone

Epiphysis

Wide part at each endArticulation with other bonesMostly spongy (cancellous) boneCovered with compact bone (cortex)

Metaphysis

Where diaphysis and epiphysis meet

Osteon (Haversian System)

A unit of bone

Central (Haversian) canal

Run lengthwise in long bonesCarries blood vessels and nerves

Perforating (Volkman's) canal

Canal perpendicular to the central canalCarries blood vessels and nerves

Lacunae

Cavities containing bone cells (osteocytes)Arranged in concentric rings

Lamellae

Rings around the central canalSites of lacunae

Canaliculi

Allow for transportRadiate from the central canal to lacunae

Yellow Bone Marrow

has adipose tissue (fat) that stores energy

Red Bone Marrow

forms blood cells (hematopoiesis)

Bone cells make up \___% of bone mass

2

Four types of cells in bones

OsteocytesOsteoblastsOsteogenic cellsOsteoclasts

Osteocytes

bone cells

Osteoblasts

bone forming cells

Osteogenic cells

stem cells

Osteoclasts

Bone-destroying cells

In embryos

the skeleton is primarily \___ cartilage

During development

most hyaline cartilage is replaced by \___

Cartilage remains in isolated areas:

Bridge of the noseParts of ribsJoints

Human bones grow until about age \___

25

Osteogenesis

Bone formation

Ossification

The process of replacing other tissues with bone

Calcification

The process of depositing calcium saltsOccurs during bone ossification and in other tissues

Two main forms of ossification

Endochondral ossificationIntramembranous ossification

Endochondral Ossification

Ossifies bones that originate as hyaline cartilageMost bones originate as hyaline cartilageThere are seven main steps in endochondral ossification

Intramembranous (dermal) Ossification

Occurs in the dermisProduces dermal bones such as mandible (lower jaw) and clavicle (collarbone)

Types of bone fractures

Closed (simple) fractureOpen (compound) fracture

Closed (simple) fracture

Break that does not penetrate the skin

Open (compound) fracture

Broken bone penetrates through the skin

Types of Fractures

DisplacedEpiphysealCollesCompressionComminutedGreenstickTransverseSpiralPott's

Transverse

break a bone shaft along its long axis

Displaced

produce new and abnormal bone arrangements

Compression

occur in vertebrae subjected to stress

Spiral

produced by the twisting stresses along the length of the bone

Epiphyseal

tend to occur where the bone matrix is undergoing calcification

Comminuted

shatter the affected area into many fragments

Greenstick

only one side of broken

Colles

break in distal portion of the radius

Pott's

occurs at ankle

Repair of bone fractures

1. Fracture hematoma formation2. Callus formation3. Spongy bone formation4. Compact bone formation

Fracture hematoma formation

blood-filled swelling is formed

Callus formation

break is splinted by fibrocartilage to form a callus

Spongy bone formation

fibrocartilage callus is replaced by a bone callus

Compact bone formation

bone callus is remodeled to form a permanent patch

Osteoporosis

Severe bone lossAffects normal functionOver age 45

Axial skeleton

Forms the longitudinal part of the bodyDivided into three parts

Three parts of axial skeleton

SkullVertebral columnBony thorax

Skull

Protects the brain

Skull contains

22 bones8 cranial bones14 facial bones

Cranial bones

form the braincase

Facial bones

protect and support entrances to digestive and respiratory tracts

Sinuses

Cavities that decrease the weight of the skullLine with mucous membranesProtect the entrances of the respiratory system

Fetal skull

large compared to the infants total body lengthallows the brain to growconverts to bone within 24 months after birth

3 parts of sternum

manubrium

Fontanelles

fibrous membranes connecting the cranial bones

Vertebrae

Separated by intervertebral discs

Spinal curves

Cervical curveThoracic curveLumbar curveSacral curve

Cervical curve

a secondary curve

Thoracic curve

a primary curve

Lumbar curve

a secondary curve

it develops with the ability to stand.L1 - L5

Sacral curve

a primary curve

Coccyx

4 fused vertebrae

Bony thorax

Forms a cage to protect major organsMade up of three parts

Three parts that make up the bony thorax

SternumRibsThoracic vertebrae

Appendicular Skeleton

126 bonesAllows humans to move and manipulate objectsIncludes all bones besides axial skeleton

The supportive girdles

pectoralpelvic

Pectoral (shoulder) girdle

Clavicle (collarbone)Scapula (shoulder blade)

Clavicle and scapula allow \___

Allows the upper limb to have exceptionally free movement

The arm is formed by \___

Humerus

Forearm is formed by \___

UlnaRadius

Hand is formed by

Carpals (wrist)Metacarpals (palm)Phalanges (fingers)

Pelvic Girdle

Hip bonesThe total weight of the upper body rests on the pelvisProtects several organs

Pelvic Girdle is composed of three pair of fused bones

IliumIschiumPubic bone

Organs that the pelvic girdle protects

Reproductive organsUrinary bladderPart of the large intestine

The thigh has \___

Femur