William Sweetman

Skeletal System Consists of bones, cartilage, joints, ligaments, and tendons Made of connective tissues Connective Tissue Type of tissue in which the proportion of cells to extracellular matrix is small Bone A form of connective tissue, is one of the hardest tissues in the body

 The formation of bones from fibrous tissues, continues until maturity  Bone growth is balanced between the actions of osteoblasts and osteoclats  Osteoblasts: immature bone cells that produce bony tissue  Osteoclats: are phagocyte cells that eat away bone tissue from the medullary cavity of the bone

 When osteoblasts mature they become osteocytes  Red bone marrow, located in cancellous bone, is hematopoietic ◦ Produces red blood cells, white blood cells, and clotting cells ◦ The medullary cavity of bone, or inner space of bone, contains yellow bone marrow  In adult animals, yellow bone marrow replaces red marrow

Cartilage Another form of connective tissue more elastic than bone Articular cartilage Covers the joint surfaces of bone Meniscus A curved fibrous cartilage found in some joints that cushions force applied to joints

 Connections between bones  Classifications › Synarthroeses: allow no movement › Amphiarthroses: allow slight movement › Diarthroses: allow free movement  Suture: a jagged line where bones join and form a non-movable joint

 Fontanelle: a soft spot remaining at a junction of sutures that usually close at birth  Symphysis: a joint where two bones join and are held firmly together so they form a junction  Ball-and-sock joints: a wide range of motions in many directions

 Ligaments: a band of fibrous connective tissue that connect bones  Tendons: A band of fibrous connective tissues that connect muscle to bones  Brusa: a fibrous sac that acts as a cushion to ease movement in areas of friction

Synovial Membrane and Fluid  Synovial Membrane: the inner lining of Bursae and synovial joints Secretes synovial fluid which acts as a lubricant to make joint movement smooth

Axial and Appendicular Skeleton  Axial  The frame work of the body  Appendicular  Consists of extremities, shoulder, pelvic griddle, and cranium  Vertebral Colum  Supports the head and body, and protects the spinal cord

B ODY Solid portion ventral to the spinal cord; midline portion Arch The dorsal part of the vertebrae that surrounds the spinal cord Lamina: the left or right dorsal halves of the arch Spinous process: a single projection from the dorsal part of the vertebral arch

Transverse and Articular process  Transversal process: project laterally from the right and left sides of the vertebral arch  Articular process: are paired cranial and caudal projections located on the dorsum of the vertebral arch  Vertebral foramen: an opening in the midline of the vertebra through which the spinal cord passes through

Bone classifications Ribs: paired bones attached to the thoracic vertebra Sternum: the breastbone, forms midline ventral portion of rib cage Manubrium: the cranial portion Xiphoid: the caudal portion Thoracic cavity: protects hearts and lungs

Bone classifications Scapula: the shoulder blades Clavicle: the collarbone Humorous: the long bone of the proximal limb Radius: the cranial bone of the front limb Ulna: the caudal bone of the front limb Olecranon: proximal projection found in the ulna

Carpal bones: irregular shaped in the area known as the wrist Metacarpals; bones found distal to the carpals Splint bones: in horses metacarpals 2 and 4 do not articulate with the phalanges Interosseous: splint bones attached by ligaments to the large third metacarpal (cannon bone)

Bone classifications Phalanges: the bones of the digits Digit: bones analogous to the human figure Sesamoid bones: small nodular bones embedded in a tendon or joint capsule Femur: the proximal long bone of the rear Patella: a large sesamoid bone in the rear limb Tibia: the larger and more weight bearing bone

Bone classifications Fibula: a long slender bone Ambulation: a type of movement involving running, walking, or moving from one place to another Fascia: a sheet of fibrous connective tissue that covers, supports, and separates muscles Linea alba: a fibrous band of connective tissue on the ventral abdominal wall

 Three main parts; the hip  Ilium: the largest pair, blade shaped  Ischiam: the caudal part of the bones  Pubis: the ventral pair of bones that are fused on the midline by a cartilaginous joint  Acetabalum: the largest socket of the pelvic bone that forms where the 3 bones meet

Ranges of Motion Abductor: muscle that moves away from midline Adductor: muscle moves towards midline Flexor: muscle that bends at its joint Extensor: muscle that straightens Levator: muscle that rises Rotator: muscle that rotates

 Depressor: muscle that lowers  Supinator: muscle that rotates  Pronator: muscle that rotates

 Pectoral: chest  Epaxial: pelvic axis  Intercostal: between the ribs  Infraspinatus: located beneath the spine of the scapula  Supraspinatus: located above the spine of the scapula  Orbicularis: muscles surrounding another structure