Skeletal CartilageSkeletal Cartilage

Contains no blood vessels or nervesContains no blood vessels or nerves Surrounded by the perichondrium (dense Surrounded by the perichondrium (dense

irregular connective tissue) that resists irregular connective tissue) that resists outward expansionoutward expansion

Three types – hyaline, elastic, and Three types – hyaline, elastic, and fibrocartilagefibrocartilage

Hyaline CartilageHyaline Cartilage

Provides support, flexibility, and resilienceProvides support, flexibility, and resilience Is the most abundant skeletal cartilageIs the most abundant skeletal cartilage Is present in these cartilages:Is present in these cartilages:

Articular – covers the ends of long bonesArticular – covers the ends of long bones Costal – connects the ribs to the sternumCostal – connects the ribs to the sternum Respiratory – makes up larynx, reinforces air Respiratory – makes up larynx, reinforces air

passagespassages Nasal – supports the noseNasal – supports the nose

Elastic CartilageElastic Cartilage

Similar to hyaline cartilage, but contains Similar to hyaline cartilage, but contains elastic fiberselastic fibers

Found in the external ear and the epiglottisFound in the external ear and the epiglottis

FibrocartilageFibrocartilage

Highly compressed with great tensile strengthHighly compressed with great tensile strength Contains collagen fibersContains collagen fibers Found in menisci of the knee and in Found in menisci of the knee and in

intervertebral discsintervertebral discs

Growth of CartilageGrowth of Cartilage

Appositional – cells in the perichondrium Appositional – cells in the perichondrium secrete matrix against the external face of secrete matrix against the external face of existing cartilageexisting cartilage

Interstitial – lacunae-bound chondrocytes Interstitial – lacunae-bound chondrocytes inside the cartilage divide and secrete new inside the cartilage divide and secrete new matrix, expanding the cartilage from withinmatrix, expanding the cartilage from within

Calcification of cartilage occursCalcification of cartilage occurs During normal bone growthDuring normal bone growth During old ageDuring old age

Bones and Cartilages of the Human Bones and Cartilages of the Human BodyBody

Figure 6.1

Classification of BonesClassification of Bones

Axial skeleton – bones of the skull, vertebral Axial skeleton – bones of the skull, vertebral column, and rib cagecolumn, and rib cage

Appendicular skeleton – bones of the upper Appendicular skeleton – bones of the upper and lower limbs, shoulder, and hipand lower limbs, shoulder, and hip

Classification of Bones: By ShapeClassification of Bones: By Shape

Long bones – Long bones – longer than longer than they are wide they are wide

(e.g., (e.g., humerus)humerus)

Figure 6.2a

Classification of Bones: By ShapeClassification of Bones: By Shape

Short bonesShort bones Cube-shaped Cube-shaped

bones of the bones of the wrist and wrist and ankleankle

Bones that Bones that form within form within tendons (e.g., tendons (e.g., patella)patella)

Figure 6.2b

Classification of Bones: By ShapeClassification of Bones: By Shape

Flat bones – Flat bones – thin, thin, flattened, flattened, and a bit and a bit curved (e.g., curved (e.g., sternum, and sternum, and most skull most skull bones)bones)

Figure 6.2c

Classification of Bones: By ShapeClassification of Bones: By Shape

Irregular Irregular bones – bones – bones with bones with complicated complicated shapes (e.g., shapes (e.g., vertebrae vertebrae and hip and hip bones)bones)

Figure 6.2d

Function of BonesFunction of Bones

Support – form the framework that supports Support – form the framework that supports the body and cradles soft organsthe body and cradles soft organs

Protection – provide a protective case for the Protection – provide a protective case for the brain, spinal cord, and vital organsbrain, spinal cord, and vital organs

Movement – provide levers for musclesMovement – provide levers for muscles

Function of BonesFunction of Bones

Mineral storage – reservoir for minerals, Mineral storage – reservoir for minerals, especially calcium and phosphorusespecially calcium and phosphorus

Blood cell formation – hematopoiesis occurs Blood cell formation – hematopoiesis occurs within the marrow cavities of boneswithin the marrow cavities of bones

Bone MarkingsBone Markings

Bulges, depressions, and holes that serve as: Bulges, depressions, and holes that serve as: Sites of attachment for muscles, ligaments, and Sites of attachment for muscles, ligaments, and

tendonstendons Joint surfacesJoint surfaces Conduits for blood vessels and nervesConduits for blood vessels and nerves

Bone Markings: Projections – Bone Markings: Projections – Sites of Muscle and Ligament Sites of Muscle and Ligament

AttachmentAttachment

Tuberosity – rounded projectionTuberosity – rounded projection Crest – narrow, prominent ridge of boneCrest – narrow, prominent ridge of bone Trochanter – large, blunt, irregular surfaceTrochanter – large, blunt, irregular surface Line – narrow ridge of boneLine – narrow ridge of bone

Tubercle – small rounded projectionTubercle – small rounded projection Epicondyle – raised area above a condyleEpicondyle – raised area above a condyle Spine – sharp, slender projectionSpine – sharp, slender projection Process – any bony prominenceProcess – any bony prominence

Bone Markings: Projections – Bone Markings: Projections – Sites of Muscle and Ligament Sites of Muscle and Ligament

AttachmentAttachment

Bone Markings: Projections – Bone Markings: Projections – Projections That Help to Form Projections That Help to Form

JointsJoints Head – bony expansion carried on a narrow Head – bony expansion carried on a narrow

neckneck Facet – smooth, nearly flat articular surfaceFacet – smooth, nearly flat articular surface Condyle – rounded articular projectionCondyle – rounded articular projection Ramus – armlike bar of boneRamus – armlike bar of bone

Bone Markings: Depressions and Bone Markings: Depressions and OpeningsOpenings

Meatus – canal-like passagewayMeatus – canal-like passageway Sinus – cavity within a boneSinus – cavity within a bone Fossa – shallow, basin-like depressionFossa – shallow, basin-like depression Groove – furrowGroove – furrow Fissure – narrow, slit-like openingFissure – narrow, slit-like opening Foramen – round or oval opening through a Foramen – round or oval opening through a

bonebone

Gross Anatomy of Bones: Bone Gross Anatomy of Bones: Bone TexturesTextures

Compact bone – dense outer layerCompact bone – dense outer layer Spongy bone – honeycomb of trabeculae filled Spongy bone – honeycomb of trabeculae filled

with yellow bone marrowwith yellow bone marrow

Bone MarkingsBone Markings

Table 6.1

Structure of Long BoneStructure of Long Bone

Long bones consist of a diaphysis and an Long bones consist of a diaphysis and an epiphysisepiphysis

DiaphysisDiaphysis Tubular shaft that forms the axis of long bonesTubular shaft that forms the axis of long bones Composed of compact bone that surrounds the Composed of compact bone that surrounds the

medullary cavitymedullary cavity Yellow bone marrow (fat) is contained in the Yellow bone marrow (fat) is contained in the

medullary cavitymedullary cavity

Structure of Long BoneStructure of Long Bone

EpiphysesEpiphyses Expanded ends of long bonesExpanded ends of long bones Exterior is compact bone, and the interior is Exterior is compact bone, and the interior is

spongy bonespongy bone Joint surface is covered with articular (hyaline) Joint surface is covered with articular (hyaline)

cartilagecartilage Epiphyseal line separates the diaphysis from the Epiphyseal line separates the diaphysis from the

epiphysesepiphyses

Structure of Long BoneStructure of Long Bone

Figure 6.3

Structure of Long BoneStructure of Long Bone

Figure 6.3a

Structure of Long BoneStructure of Long Bone

Figure 6.3b

Structure of Long BoneStructure of Long Bone

Figure 6.3c

Bone MembranesBone Membranes

Periosteum – double-layered protective Periosteum – double-layered protective membranemembrane Outer fibrous layer is dense regular connective tissueOuter fibrous layer is dense regular connective tissue Inner osteogenic layer is composed of osteoblasts Inner osteogenic layer is composed of osteoblasts

and osteoclastsand osteoclasts Richly supplied with nerve fibers, blood, and Richly supplied with nerve fibers, blood, and

lymphatic vessels, which enter the bone via nutrient lymphatic vessels, which enter the bone via nutrient foraminaforamina

Secured to underlying bone by Sharpey’s fibersSecured to underlying bone by Sharpey’s fibers

Bone MembranesBone Membranes

Endosteum – delicate membrane covering Endosteum – delicate membrane covering internal surfaces of boneinternal surfaces of bone

Structure of Short, Irregular, Structure of Short, Irregular, and Flat Bonesand Flat Bones

Thin plates of periosteum-covered compact Thin plates of periosteum-covered compact bone on the outside with endosteum-covered bone on the outside with endosteum-covered spongy bone (diploë) on the insidespongy bone (diploë) on the inside

Have no diaphysis or epiphysesHave no diaphysis or epiphyses Contain bone marrow between the trabeculaeContain bone marrow between the trabeculae

Structure of a Flat BoneStructure of a Flat Bone

Figure 6.4

Location of Hematopoietic Tissue Location of Hematopoietic Tissue

(Red Marrow)(Red Marrow) In infantsIn infants Found in the medullary cavity and all areas of Found in the medullary cavity and all areas of

spongy bone spongy bone In adultsIn adults

Found in the diploë (between inner and outer Found in the diploë (between inner and outer walls) of flat bones, and the head of the femur and walls) of flat bones, and the head of the femur and humerushumerus

Microscopic Structure of Bone: Microscopic Structure of Bone: Compact BoneCompact Bone

Haversian system, or osteon – the structural Haversian system, or osteon – the structural unit of compact boneunit of compact bone Lamella – weight-bearing, column-like matrix Lamella – weight-bearing, column-like matrix

tubes composed mainly of collagentubes composed mainly of collagen Haversian, or central canal – central channel Haversian, or central canal – central channel

containing blood vessels and nervescontaining blood vessels and nerves Volkmann’s canals – channels lying at right angles Volkmann’s canals – channels lying at right angles

to the central canal, connecting blood and nerve to the central canal, connecting blood and nerve supply of the periosteum to that of the Haversian supply of the periosteum to that of the Haversian canalcanal

Microscopic Structure of Bone: Microscopic Structure of Bone: Compact BoneCompact Bone

Osteocytes – mature bone cellsOsteocytes – mature bone cells Lacunae – small cavities in bone that contain Lacunae – small cavities in bone that contain

osteocytesosteocytes Canaliculi – hairlike canals that connect Canaliculi – hairlike canals that connect

lacunae to each other and the central canallacunae to each other and the central canal

Microscopic Structure of Bone: Microscopic Structure of Bone: Compact BoneCompact Bone

Figure 6.6a, b

Microscopic Structure of Bone: Microscopic Structure of Bone: Compact BoneCompact Bone

Figure 6.6a

Microscopic Structure of Bone: Microscopic Structure of Bone: Compact BoneCompact Bone

Figure 6.6b

Microscopic Structure of Bone: Microscopic Structure of Bone: Compact BoneCompact Bone

Figure 6.6c

Chemical Composition of Bone: Chemical Composition of Bone: OrganicOrganic

Osteoblasts – bone-forming cellsOsteoblasts – bone-forming cells Osteocytes – mature bone cellsOsteocytes – mature bone cells Osteoclasts – large cells that resorb or break Osteoclasts – large cells that resorb or break

down bone matrixdown bone matrix Osteoid – unmineralized bone matrix Osteoid – unmineralized bone matrix

composed of proteoglycans, glycoproteins, composed of proteoglycans, glycoproteins, and collagenand collagen

Chemical Composition of Bone: Chemical Composition of Bone: InorganicInorganic

Hydroxyapatites, or mineral saltsHydroxyapatites, or mineral salts Sixty-five percent of bone by massSixty-five percent of bone by mass Mainly calcium phosphatesMainly calcium phosphates Responsible for bone hardness and its resistance to Responsible for bone hardness and its resistance to

compressioncompression

Bone DevelopmentBone Development

Osteogenesis and ossification – the process of Osteogenesis and ossification – the process of bone tissue formation, which leads to:bone tissue formation, which leads to: The formation of the bony skeleton in embryosThe formation of the bony skeleton in embryos Bone growth until early adulthoodBone growth until early adulthood Bone thickness, remodeling, and repairBone thickness, remodeling, and repair

Formation of the Bony SkeletonFormation of the Bony Skeleton

Begins at week 8 of embryo developmentBegins at week 8 of embryo development Intramembranous ossification – bone develops Intramembranous ossification – bone develops

from a fibrous membranefrom a fibrous membrane Endochondral ossification – bone forms by Endochondral ossification – bone forms by

replacing hyaline cartilagereplacing hyaline cartilage

Intramembranous OssificationIntramembranous Ossification

Formation of most of the flat bones of the Formation of most of the flat bones of the skull and the claviclesskull and the clavicles

Fibrous connective tissue membranes are Fibrous connective tissue membranes are formed by mesenchymal cellsformed by mesenchymal cells