WEEK 3 - General Osteology.pdf

BONE TISSUE General Osteology BONE “Stronger than concrete and nearly as strong as steel” SKELETAL SYSTEM BONES CARTILAGES JOINTS (Articulations) BONE The study of bones is OSTEOLOGY The study of joints is ARTHROLOGY Classes of bone: LONG SHORT FLAT IRREGULAR Hum...

BONE TISSUE General Osteology BONE “Stronger than concrete and nearly as strong as steel” SKELETAL SYSTEM BONES CARTILAGES JOINTS (Articulations) BONE The study of bones is OSTEOLOGY The study of joints is ARTHROLOGY Classes of bone: LONG SHORT FLAT IRREGULAR Human skeleton is a living skeleton = Endoskeleton Insects have a non-living skeleton = Exoskeleton Classification of bones FUNCTIONS OF BONE Support Protection Acts as a lever (with muscles) for movement Storage/Release area for minerals Blood cell formation (RBCs) Triglyceride storage (Yellow bone marrow) TYPES OF OSSIFICATION ENDOCHONDRAL: Bone forms by replacement of hyaline cartilage (long bones of the extremities) INTRAMEMBRANOUS: Forms directly in the matrix by increasing growth of collagenous fibers (flat bones of the skull and face) BONE TISSUE Complex and dynamic living tissue Continually remodeling Several tissue working together : osseous, cartilage, dense connective tissue, epithelium, adipose and nervous Basic functions: 1. Support 2. Protect 3. Assist in movement 4. Storage and release of minerals 5. Blood cell production 6. Storage of triglycerides BONE CELLS GENERAL FEATURES OF BONE Diaphysis Epiphyses Metaphyses Epiphyseal plate Articular cartilage Periosteum Medullary cavity Endosteum Compact Bone Observed at the surface of a bone, but can extend deeper Makes up most of the diaphysis of long bones Looks dense (solid) to the naked eye, however actually quite porous when viewed microscopically Offers protection and support Resistant to stresses caused by weight and movement COMPACT BONE TISSUE Osteons (Haversian systems) Structural unit of compact bone Osteonic (Haversian) canal Concentric Lamella(e) Lacunae Space between the lamellae Contain osteocytes Canaliculi COMPACT BONE TISSUE Interstitial lamellae Interosteonic (Volkmann) canals Circumferential lamellae Perforating (Sharpey’s) fibers PERIOSTEUM Fibrous membrane surrounding complete bone Covers Diaphysis ØDoes not surround bone ends at articular cartilage Two layers Outer layer – FIBROUS Inner layer - OSTEOGENIC SPONGY BONE TISSUE Also known as trabecular or cancellous bone Does not contain Osteons Located in the interior of bone, protected by a covering of compact bone Trabeculae: lamellae arranged in an irregular pattern of thin columns Concentric lamellae Osteocytes Lacunae Canaliculi Spaces between the trabeculae are filled with red bone marrow (blood cell production) or yellow bone marrow (adipose tissue) BLOOD SUPPLY Periosteal arteries Enter diaphysis through interosteonic canals Supply periosteum and outer part of compact bone Nutrient artery Enters near center of diaphysis via oblique angled hole called nutrient foramen Path is always away from the dominant growth end of the bone “Go to the elbow and flee the knee!” Metaphyseal arteries Arise from arteries around associated joint Epiphyseal arteries Arise from arteries around associated joint BLOOD SUPPLY BONE FORMATION 4 STAGES Initial formation in embryo and fetus General growth through infancy, childhood, and early adulthood Bone remodeling through life Repair (from fractures) through life BONE FORMATION Initially from mesenchyme, a connective tissue found in the embryo Forms the “general” shape of bone Then goes through one or other type of OSSIFICATION OSSIFICATION INTRAMEMBRANOUS Ossification ØFound in flat bones (skull), most facial bones, and mandible ENDOCHONDRAL Ossification ØMost other bones formed this way including all long bones INTRAMEMBRANOUS Ossification 1. Development of the ossification center 2. Calcification 3. Formation of trabeculae 4. Development of the periosteum ENDOCHONDRAL OSSIFICATION 1. Development of the cartilage model 2. Growth of the cartilage model 3. Development of the primary ossification center 4. Development of the medullary cavity 5. Development of the secondary ossification centers 6. Formation of articular cartilage and the epiphyseal (growth) plate Growth in length (Epiphyseal plate) Zone of reserve/resting cartilage Closes to the epiphysis, consists of small scattered chondrocytes Zone of proliferating cartilage Larger chondrocytes undergo interstitial growth, divide and secrete extracellular matrix Zone of hypertrophic cartilage Large maturing chondrocytes Zone of calcified cartilage Dead chondrocytes because extracellular matrix has calcified Osteoclasts dissolve calcified cartilage, then osteoblasts and capillaries invade area Osteoblasts lay down bone extracellular matrix, process of endochondral ossification, new diaphysis formed as a result Bone growth in thickness Bone Modeling Cartilage model is fairly close to general shape of mature bone Final shape is determined by Ø GRAVITATIONAL FORCES (Pressure Epiphyses) Ø FUNCTIONAL FORCES (Traction Epiphyses) Open (compound) Fracture Comminuted Fracture Greenstick Fracture Impacted Fracture Pott Fracture Colles Fracture Osteoporotic bone JOINTS JOINT CLASSIFICATION SYNARTHROSIS è FIBROUS “Immoveable” ü Suture ü Syndesmosis ü Gomphosis AMPHIARTHROSIS è CARTILAGENOUS “Slighlty moveable” ü Symphysis ü Synchondrosis DIARTHROSIS è SYNOVIAL “Freely moveable” ü Arthrodial, Ellipsoidal, Ginglymus, Sellar, Enarthrodial, Trochoid FIBROUS Joints FIBROUS Joints FIBROUS Joints CARTILAGENOUS Joints SYNOVIAL (Diarthrotic) JOINTS Characteristics: üJoint capsule üArticulating surface üArticular cartilage üSynovial membrane üSynovial fluid SYNOVIAL JOINTS ARTHRODIAL (Gliding) Joints GINGLYMUS (Hinge) Joints TROCHOID (Pivot) Joints ELLIPSOIDAL (Condyloid) Joints SELLAR (Saddle) Joint ENARTHRODIAL (Ball-and-Socket) LEVER SYSTEMS Human movement is caused by the long bones of the body, the joints connecting them, and the muscles that cross these joints A lever system has 4 components: A rigid body to use as a LEVER A FULCRUM around which the lever moves A FORCE applied to the lever to cause motion A FORCE applied to the lever that gives resistance In the human body, the long bones function as the lever, the joints act as the fulcrum, the muscles act as the moving force, and the force of gravity or a weight will act as either a moving of resistive force. FIRST CLASS Lever First Class Lever: Fulcrum is between the moving force (muscle) and the resistance (weight) SECOND CLASS Lever Second Class Lever: The resistance lies between the fulcrum and the force THIRD CLASS Lever Third Class Lever: The force is placed between the fulcrum and the resistive force