BONE AND CARTILAGE

BONE AND CARTILAGEWHAT IS BONE?BONE IS A CALICIFIED, LIVING,CONNECTIVE TISSUE THAT FORMS THE MAJORITY OF THE SKELETON. IT CONSISTS OF AN INTRACELLULAR CALCIFIED MATRIX, WHICH ALSO CONTAINS COLLAGEN FIBERS AND SEVERAL TYPES OF CELLS WITH IN THE MATRIX.BONES OF THE SKELETON ARE COMPLEX,DYNAMIC ORGANS CONTAINING ALL TISSUE TYPES.THE PRIMARY COMPONENT IS BONE CONNECTIVE TISSUE ,ALSO CALLED OSSEOUS CONNECTIVE TISSUE.THEY ALSO CONTAIN CONNECTIVE TISSUE PROPER, CARTILAGE CONNECTIVE TISSUE ,SMOOTH MUSCLE TISSUE ,FLUID CONNECTIVE TISSUE,EPITHELIAL TISSUE AND NERVOUSE TISSUE.THE MATRIX OF BONE CONNECTIVE TISSUE IS STURDY AND RIGID DUE TO DEPOSITION OF MINERALS IN THE MATRIX CALCIFICATION.

FUNCTIONS OF BONE

PROVIDES LOCOMOTION.PROVIDES STRUCTURAL SUPPORT AND SERVE AS A FRAMEWORK FOR THE ENTIRE BODY.PROTECTS DELICATE TISSUES AND ORGANS FROM INJURY AND TRAUMA.E.g. RIBCAGE PROTECTS HEART AND THE LUNGS, CRANIAL BONES ENCLOSE AND PROTECT BRAIN, VERTEBRAE ENCLOSES SPINAL CORD.RESERVOIRS OF CALCIUM AND PHOSPHOROUS.PRODUCTION OF BLOOD CELLS.

STRUCTURE OF THE BONE Epiphysis: The rounded ends of a bone.Diaphysis: Shaft of the bone.Articular cartilage: which reduces friction and absorbs shocks at free movable joints.Spongy bone Endosteum : Membrane that lines the cavity of the bone Periosteum: tough membrane that surrounds the bone where ever they arent covered by the articular cartilage.Medullary cavity: the cavity inside the bone which consists of bone marrow ( yellow in adults).Nutrient foramen: external opening of the nutrient canal in the bone.Epiphyseal line: the part of the bone which replaces the epiphyseal plate.Spongy bone Compact bone

CLASSIFICATION THE BONES

BONES ARE CLASSIFIED ON THE BASIS OF :SHAPE AND STRUCTUREDEVELOPMENT REGIONMACROSCOPIC CLASSIFICATIONMICROSCOPIC CLASSIFICATION

CLASSIFICATION ON THE BASIS OF SHAPE AND STRUCTURE

LONG BONESSHORT BONESFLAT BONESIRREGULAR BONESSESAMOID BONE PNEUMATIC BONES

LONG BONES

MOST COMMON BONE SHAPEHAVE GREATER LENGTH THAN WIDTHELONGATED CYLINDRICAL SHAFT

SHORT BONES

HAVE LENGTH NEARLY EQUAL TO THEIR WIDTHEXTERNAL SURFACES OF SHORT BONES ARE COVERED BY COMPACT BONE AND INTERIOR IS COMPOSED OF SPONGY BONE.E.g. CARPELS AND TARSELS

FLAT BONES

THEY HAVE FLAT ,THIN SURFACESCOMPOSED OF ROUGH PARALLEL SURFACE OF COMPACT BONE WITH A LAYER OF INTERNALY PLACED SPONGY BONEE.g. SCAPULA , STERNUM

IRREGULAR BONES

HAVE AN IRREGULAR AND COMPLEX SHAPE E.g.vertebrae, ossa coxae

SESAMOID BONES ROUND OR OVAL BONES THAT DEVELOP IN THE ARTERIES E.g. PATELA

PNEUMATIC BONES

THESE BONES HAVE AIR SPACES THESE AIR SPACES KEEPS THE BONE LIGHTER IN WEIGHTE.G.MAXILARY BONES, SPHENOID , ETHMOITAL MACROSCOPIC CLASSIFICATION COMPACT BONES SPONGY BONES MICROSCOPIC CLASSIFICATIONLAMELLER BONE NON LAMELLER BONECLASSIFICATION ON THE BASIS OF DEVELOPEMENTENDOCHONDRALINTRAMEMBRANOUS CARTILAGE IT IS A SEMI RIGID CONNECTIVE TISSUE WHICH IS WEAKER THAN BONE AND IS MORE RESILIENT.IT CONSISTS OF SPECIAL CELLS CALLED THE CHONDROCYTES ALONG WITH COLLAGEN IT IS INSENSITIVE AS IT DOES NOT HAVE ANY NERVE SUPPLYHYALINE CARTILAGE

MOST ABUNDANT TYPE OF CARTILAGE IT PROVIDES SUPPORT THROUGH FLEXIBILITY AND RESILIENCE AND ITS EXTRACELLULAR MATRIX HAS TRANSLUCENT APPEARANCE, WITH NO CLEARLT VISIBLE COLLAGEN FIBERS WHEN VIEWED IN A MICROSCOPE SECTION.MOST HYLAINE CARTILAGE IS SURROUNDED BY A DENSE CONNECTIVE TISSUE COVERING CALLED PERICHONDRIUM.FOUND: TRACHEA, PORTIONS ON LARYNX, THE ARTICULLAR CARTILLAGE ON BONE. FIBROUS CARTILAGE

IT HAS AN EXTRACELLULAR MATRIX WITH THICK COLLAGEN FIBERS THAT HELP RESIST BOTH TENSILE AND COMPRESSIVE FORCES.IT ACTS AS A SHOCK ABSORBER IT LACKS A PERICHONDRIUM BECAUSE STRESS APPLIED AT THE SURFACE WOULD QUICKLY DESTROY THIS LAYER.FOUND:PUBIC SYMPHOSIS, INVERTEBRAL DISCS,MENISCI OF THE KNEEELASTIC CARTILAGE

ELASTIC CARTILAGE CONTAINS HIGHLY BRANCED ELASTIC FIBERS WITH ITS EXTRACELLULAR MATRIX.IT IS SURROUNDED BY A PERICHONDRIUM ITS TYPICALLY FOUND IN THE REGIONS REQUIRING A HIGHLY FLEXIBLE FORM OF A SUPPORT.FOUND: AURICLE OF THE EAR ,EPIGLOTTIS.