Anatomy and Physiology of Dogs and Cats Bones, Joints, Synovial Fluid

Bones Cellular structures where the extracellular fluid environment of the cell is surrounded by a rigid, calcified frame

Function of the Skeleton Gives identifiable form to body Provides protection Location of blood formation Mineral source Movement Accommodates loads and stresses

Joint Moveable union between two bones Enclosed by a joint capsule filled with synovial fluid Why SF?

Axial Skeleton Lie on long axis (midline) of body Includes: – Skull – Vertebrae – Ribs – Sternum

Appendicular Skeleton Made up of bones of the front (pectoral) and hind (pelvic) limbs and their respective pectoral girdle (shoulder) and pelvic girdle (pelvis)

A & P of Long Bones Contains spongy (cancellous) and compact bone Spongy bone have trabeculae which are mineralized tissue Regions between trabeculae are filled with marrow

A & P of Long Bones Rigidity and strength of long bones is caused by the hardness of compact bone and the scaffolding arrangement of the trabeculae (parallel to the lines of maximum stress)

A & P of Long Bones The epiphysis refers to either extremity of a long bone and the diaphysis is the cylindrical shaft between the two epiphyses The metaphysis is the flared part of the bone at the ends of the diaphysis

A & P of Long Bones The diaphysis contains the marrow (medullary) cavity that is surrounded by compact bone – Bone marrow is the site of blood production

A & P of Long Bones The epiphyses have spongy bone surrounded by compact bone The epiphyseal plate is composed of hyaline cartilage and represents the point of growth in a longitudinal direction – In mature bones the cartilage has been replaced by bone

A & P of Long Bones The contact area of the bone that articulates with its neighboring bone at a moveable joint is covered with articular cartilage All other outer surfaces are covered with periosteum