Anatomy and Physiology of Dogs and

CatsBones, 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– In mature bones the cartilage has been replaced by bone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