2 Skeletal CartilagesConsist primarily of water this is what allows it to spring back to its original shape after being compressed.Contain no blood vessels or nervesSurrounded by dense connective tissue, the perichondriumcontains blood vessels for nutrient delivery to cartilageacts as a girdle to resist outward expansion
3 Skeletal Cartilages Hyaline cartilages Elastic cartilages Provide support, flexibility, and resilienceMost abundant typeElastic cartilagesSimilar to hyaline cartilages, but contain more stretchy elastic fibersBetter able to stand up to repeated bendingOnly found in the external ear and the epiglottisFibrocartilagesCollagen fibers—have great tensile strengthAreas subjected to heavy pressure and stretch- menisci (knee)
4 Respiratory tube cartilages in neck and thorax EpiglottisLarynxThyroidcartilageCartilage inexternal earCartilages innoseTracheaCricoidcartilageLungArticularCartilageof a jointCartilage inIntervertebral discCostalcartilageRespiratory tube cartilagesin neck and thoraxPubicsymphysisBones of skeletonAxial skeletonMeniscus (padlikecartilage inknee joint)Appendicular skeletonCartilagesArticular cartilageof a jointHyaline cartilagesElastic cartilagesFibrocartilagesFigure 6.1
5 Growth of Cartilage Cartilage grows in two ways: Appositional “growth from the outside”Cells secrete matrix against the external face of existing cartilageInterstitial “growth from the inside”Chondrocytes divide and secrete new matrix, expanding cartilage from withinUnder certain conditions calcification of cartilage (calcium salts are deposited in the matrix) occurs duringNormal bone growthOld ageTHIS IS NOT BONE 2 separate tissues!
6 Bones of the Skeleton Two main groups, by location Axial skeleton (brown)Skull, vertebral column, and rib cageAppendicular skeleton (yellow)Bones of the upper and lower limbs and the girdles.
7 Cartilage in Cartilages in external ear nose Articular Cartilage of a jointCartilage inIntervertebral discCostalcartilagePubicsymphysisMeniscus (padlikecartilage inknee joint)Articular cartilageof a jointFigure 6.1
8 Classification of Bones by Shape Long bonesLonger than they are wideAll limb bones except the patella, wrist, and ankle bone are long bones.Short bonesCube-shaped bones (in wrist and ankle)Sesamoid bones (within tendons patella)
9 Classification of Bones by Shape Flat bonesThin, flat, slightly curvedSternum, scapulae, ribs, and most skull bonesIrregular bonesComplicated shapes that fit none of the other classesVertebrae and hip bones
10 Functions of Bones Support Protection Movement For the body and soft organs (framework)ProtectionFor brain, spinal cord, and vital organsMovementLevers for muscle action muscles use bones as levers to move the body.
11 Functions of Bones Storage Minerals (calcium and phosphorus) and growth factorsBlood cell formation (hematopoiesis) in marrow cavitiesTriglyceride (energy) storage in bone cavities
12 Bone Markings Bulges, depressions, and holes serve as Sites of attachment for muscles, ligaments, and tendonsJoint surfacesChannels for blood vessels and nerves
16 Bone Textures Compact bone Spongy bone Dense outer layer that looks smooth and solidSpongy boneHoneycomb of trabeculae internal layer filled with bone marrow
17 Structure of a Long Bone Diaphysis (shaft)Forms the long axis of the boneConstructed from a thick compact bone collar that surrounds a central medullary (marrow) cavityMedullary cavity in adults contains fat (yellow marrow)
18 Structure of a Long Bone EpiphysesBone endsCompact bone exterior & spongy bone interiorEpiphyseal lineremnant of growth plate- a disc of hyaline cartilage that grows during childhood to lengthen the boneArticular (hyaline) cartilage on joint surfaces
19 Articular cartilage Compact bone Proximal epiphysis Spongy bone EpiphyseallinePeriosteumCompact boneMedullarycavity (linedby endosteum)(b)DiaphysisDistalepiphysis(a)Figure 6.3a-b
20 Membranes of Bone Periosteum Covers the entire external surface of bonesOuter fibrous layer dense irregular connective tissueInner osteogenic layer mainly bone forming cellsNerve fibers, nutrient blood vessels, and lymphatic vessels enter the bone via nutrient foraminaSecured to underlying bone by perforating “Sharpey’s” fibersTufts if collagen fibers that extend from the fibrous layer into the bone matrix
21 Membranes of Bone Endosteum Delicate connective tissue membrane on internal surfaces of boneCovers the trabeculae of spongy bone and lines the canals that pass through compact boneAlso contains osteoblasts and osteoclasts
22 Structure of Short, Irregular, and Flat Bones All consist of:Periosteum-covered compact bone on the outsideEndosteum-covered spongy bone withinSpongy bone called diploë in flat bonesBone marrow between the trabeculae
23 Location of Hematopoietic Tissue (Red Marrow) Red marrow cavities of adultsTrabecular cavities of the heads of the femur and humerusTrabecular cavities of the diploë of flat bonesIn most adult long bones the fat containing medullary cavity extends well into the epiphysis and little red marrow is present blood cell production occurs in the heads of the femur (thigh bone) and humerus (long bone of arm)The red marrow found in the diploë of flat bones (sternum) or some irregular bone (hip) is much more active in hematopoiesis and these sites are routinely used for obtaining bone marrow biopsies when problems with blood forming tissue are suspected.Red marrow of newborn infantsMedullary cavities and all spaces in spongy bone
24 Microscopic Anatomy of Bone Cells of bonesOsteogenic cellsStem cells in periosteum and endosteum that give rise to osteoblastsOsteoblastsBone-forming cellsOsteocytesMature bone cellsOsteoclastsCells that break down bone matrix
25 Microscopic Anatomy of Bone: Compact Bone Although compact bone looks solid it is riddled with passageways for nerves, blood vessels, and lymphatic vesselsOsteons—structural units“Tiny pillars”LamellaeWeight-bearingColumn-like matrix tubesHaversian canalContains blood vessels and nerves
26 Microscopic Anatomy of Bone: Compact Bone Perforating (Volkmann’s) canalsAt right angles to the central canalConnects blood vessels and nerves of the periosteum and central canalLacunae—small cavities that contain osteocytesCanaliculi—hairlike canals that connect lacunae to each other and the central canal
27 Microscopic Anatomy of Bone: Spongy Bone TrabeculaeAlign along lines of stressNo osteonsContain irregularly arranged lamellae, osteocytes, and canaliculiCapillaries in endosteum supply nutrients
28 Chemical Composition of Bone: Organic Osteogenic cells, osteoblasts, osteocytes, osteoclastsOsteoid—organic bone matrix secreted by osteoblastsGround substance (proteoglycans, glycoproteins)Collagen fibersProvide strength and flexibility
29 Chemical Composition of Bone: Inorganic Hydroxyapatites (mineral salts)Tiny, tightly packed crystals in and around the collagen fibers in the extracellular matrix65% of bone by massMainly calcium phosphate crystalsResponsible for hardness and resistance to compression
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