ANAT 121 Lecture 4 Skeletal System PDF

ANAT 121 | GROSS ANATOMY Importance: for body structure, protection of LECTURE 4 organs, and produces red blood cells. SKELETAL SYSTEM Cartila...

ANAT 121 | GROSS ANATOMY Importance: for body structure, protection of LECTURE 4 organs, and produces red blood cells. SKELETAL SYSTEM Cartilage: Flexible connective tissue with living cells Bones arrange in pairs or bundles 1/3 organic, 2/3 inorganic material Matrix contains more collagen and less mineral Average total number: 319 bones than bone this does not include the bones of the dew claw Softer and more elastic than bone since many dogs do not have this Found at the end of bones, in the nose, ears, and trachea. Three Major group of S.S Importance: Prevents friction and withstands 1. Axial- skull, vertebral column, ribs and sternum shocks. 2. Appendicular- Thoracic and Pelvic Limbs Tendons: thick strand attaching muscle to bone 3. Visceral- Baculum= os penis (dogs) Made of strong fibrous collagen. Axial Skeleton Touch and does not stretch Vertebral Column= 50 Capable of withstanding tension Skull + Hyoid = 50 Importance: Enables movement of bones. Ribs + Sternum = 34 Ligaments: A flexible band attaching a bone to another Appendicular bone Pectoral limb= 92 Made of touch elastin fibers Pelvic limb= 92 Elastic, can stand and “snap-back” Importance: Keep bones stable and prevent Heterotrophic dislocation. Baculum = 1 Function of bone Total: 319 | Adult human 206 bones Supports and protects soft organs of the body Acts as levers for muscular action Stores calcium and phosphorus Encloses the blood forming elements (RBC, WBC, Hb, platelets) and in the adult, the bone also stores fat. Topic: Bone, Cartilage, Ligaments, Tendons Bone: hard tough connective tissue with living cells arrange in rings Living Cells (osteocytes) for growing and repair Matrix secreted made mostly of minerals (calcium and phosphate) for rigid structure Contain protein (collagen) gives strengths and flexibility= less brittle and prone to breakage Classification of Bones according to Shapes o Ex. skull, jaws, gill covers, and the shell (of tortoises and turtles). 1. Long bones (ossa longa) Found mainly in the limbs/extremities Structure of the bone Has a body/shaft called diaphysis and two Compact bone (substancia compacta/corticalis) ends called the epiphyses Cancellous or spongy bone (substancia Long bones form levers and possess great spongiosa) tensile strength The spongy bone of the skull is known as End of long bones are covered by hyaline diploe. cartilage as they enter the formation of joints Long Bones Enlargement of each extremity of a long Diaphysis and epiphyses (in young, epiphyseal bone serves a dual purpose: plate) o Decreases the risk of dislocation Medullary cavity – hollow portion o Provides a large bearing surface for o Young – red marrow articulation 2. Short Bone (ossa brevis) o Adult – red and yellow marrow (fat) Cortex – compact bone surrounding the shaft of Carpal (wrist), tarsal (ankle) – contains 7 the long bone bones Associated with the spread of pressure Bone Covering Layers exerted in these regions 3. Sesamoid Bones (ossa sesamoida) Periosteum – layer of specialized connective To alter the course of tendons at the places tissue covering the non-articular surface of the where greatest friction is developed. bone 4. Flat bones (ossa plana) o Perichondrium- connective tissue Found in the thoracic and pelvic girdles and covering the cartilage of articular in the head and thorax surface For PROTECTION Endosteum – thin fibrous membrane that lines the medullary cavity and osteonal (Haversian) Weigh less canals of a bone Cranium = outer and inner tables of an compact bones and intermediate uniting Mucoperiosteum spongy bone called diploe Pneumatic bones (ossa pneumatica) – Name given to the covering of the bones which bones which contain air cavities participate in forming boundaries of the 5. Irregular Bones (ossa iregulata) respiratory or digestive system. Vertebral column, bones of the skull that Lines all of the paranasal sinuses and contains are not flat, 3 parts of the hip bone (os mucous cells coxae) Vessels and Nerve of Bones Jutting processes are the characteristic features Vessels For muscular and ligamentous attachment; Nutrient artery and vein (nutrient foramen) some for articulation Anastomosing vessel of the epiphyseal plate Development of Bone and the periosteum Endochondral/replacement/cartilage bones Nerves o bones arising from cartilages Sensory nerves Membrane/Dermal bones o develop from connective tissue sheets or membranes (roof of the cranium)