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The Function & Classification of The Function & Classification of BonesBones

Table of Contents

The Skeletal SystemThe Skeletal System

Parts of the skeletal systemParts of the skeletal system Bones (skeleton)Bones (skeleton) JointsJoints CartilagesCartilages LigamentsLigaments

Divided into two divisionsDivided into two divisions Axial skeletonAxial skeleton Appendicular skeletonAppendicular skeleton

Functions of BonesFunctions of Bones

Support of the bodySupport of the body Protection of soft organsProtection of soft organs Movement due to attached skeletal Movement due to attached skeletal

musclesmuscles Storage of minerals and fatsStorage of minerals and fats Blood cell formationBlood cell formation

Bones of the Human BodyBones of the Human Body

The adult skeleton has 206 bonesThe adult skeleton has 206 bones Two basic types of bone tissueTwo basic types of bone tissue

Compact boneCompact bone Dense & SmoothDense & Smooth HomogeneousHomogeneous

Spongy boneSpongy bone Small needle-like Small needle-like

pieces of bonepieces of bone Many open spacesMany open spaces

Figure 5.2b

Classification of Bones on the Classification of Bones on the Basis of ShapeBasis of Shape

Figure 5.1

Long BonesLong Bones

• Typically longer than Typically longer than widewide

• Have a shaft with Have a shaft with heads at both endsheads at both ends

• Contain mostly Contain mostly compact bonecompact bone

• Examples: Femur, Examples: Femur, humerushumerus

Short BonesShort Bones

Generally cube-Generally cube-shapeshape

Contain mostly Contain mostly spongy bonespongy bone

Examples: Carpals, Examples: Carpals, tarsalstarsals

Flat BonesFlat Bones

Thin and flattenedThin and flattened

Usually curvedUsually curved

Thin layers of compact Thin layers of compact bone around a layer of bone around a layer of spongy bonespongy bone

Examples: Skull, ribs, Examples: Skull, ribs, sternumsternum

Irregular BonesIrregular Bones

Irregular shapeIrregular shape

Do not fit into other bone Do not fit into other bone classification categoriesclassification categories

Example: Vertebrae and Example: Vertebrae and hiphip

HomeworkHomework

Page 174 Short Answer Essay #1-5Page 174 Short Answer Essay #1-5

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The Function & Classification of The Function & Classification of BonesBones

Structure of a Long BoneStructure of a Long Bone

Table of Contents

Gross Anatomy of a Long Gross Anatomy of a Long BoneBone

DiaphysisDiaphysis ShaftShaft Composed of Composed of

compact bonecompact bone Epiphysis Epiphysis

Ends of the boneEnds of the bone Composed mostly of Composed mostly of

spongy bonespongy bone

Figure 5.2a

Structures of a Long BoneStructures of a Long Bone PeriosteumPeriosteum

Outside covering of Outside covering of the diaphysisthe diaphysis

Fibrous connective Fibrous connective tissue membranetissue membrane

Sharpey’s fibers Sharpey’s fibers (perforating)(perforating)

Secure periosteum Secure periosteum to underlying boneto underlying bone

ArteriesArteries Supply bone cells Supply bone cells

with nutrientswith nutrientsFigure 5.2c

Structures of a Long BoneStructures of a Long Bone

Articular cartilageArticular cartilage Covers the Covers the

external surface external surface of the epiphysesof the epiphyses

Made of hyaline Made of hyaline cartilagecartilage

Decreases friction Decreases friction at joint surfacesat joint surfaces

Figure 5.2a

Structures of a Long BoneStructures of a Long Bone

Medullary cavityMedullary cavity Cavity of the shaftCavity of the shaft Contains yellow Contains yellow

marrow (mostly fat) marrow (mostly fat) in adultsin adults

Contains red Contains red marrow (for blood marrow (for blood cell formation) in cell formation) in infantsinfants

Figure 5.2a

Bone MarkingsBone Markings

Surface features of bonesSurface features of bones Sites of attachments for muscles, Sites of attachments for muscles,

tendons, and ligamentstendons, and ligaments Passages for nerves and blood vesselsPassages for nerves and blood vessels Categories of bone markingsCategories of bone markings

Projections and processes – grow out from Projections and processes – grow out from the bone surfacethe bone surface

Depressions or cavities – indentationsDepressions or cavities – indentations

Microscopic Anatomy of Microscopic Anatomy of BoneBone

Osteon (Haversian System)Osteon (Haversian System) A unit of boneA unit of bone

Central (Haversian) canalCentral (Haversian) canal Opening in the center of an osteonOpening in the center of an osteon Carries blood vessels and nervesCarries blood vessels and nerves

Perforating (Volkman’s) canalPerforating (Volkman’s) canal Canal perpendicular to the central canalCanal perpendicular to the central canal Carries blood vessels and nervesCarries blood vessels and nerves

Microscopic Anatomy of Microscopic Anatomy of BoneBone

Figure 5.3

Microscopic Anatomy of Microscopic Anatomy of BoneBone

LacunaeLacunae Cavities containing Cavities containing

bone cells bone cells (osteocytes)(osteocytes)

Arranged in Arranged in concentric ringsconcentric rings

LamellaeLamellae Rings around the Rings around the

central canalcentral canal Sites of lacunaeSites of lacunae

Detail of Figure 5.3

Microscopic Anatomy of Microscopic Anatomy of BoneBone

Canaliculi Canaliculi Tiny canalsTiny canals Radiate from the Radiate from the

central canal to central canal to lacunaelacunae

Form a transport Form a transport systemsystem

Detail of Figure 5.3