Skeletal System http://www.youtube.com/watch?v=e54m6XOpRgU

What is it? Framework of structures Made of bones & cartilage Supports & protects the body Axial Skeleton Includes skull, vertebrae, ribs, and sternum

Axial Skeleton Skull Vertebrae Many plates of bones fused together Soft spot on top of skull Fontanel Vertebrae Five distinct regions Cervical Thoracic Lumbar Sacral Coccygeal

Cervical Vertebrae of the neck region Atlas  called “C1”, the first cervical vertebra Forms joint that lets you nod “yes” Axis  called “C2”, the second cervical vertebra Forms joint that lets you nod “no” 7 cervical vertebrae in all mammals

Thoracic Vertebrae of the body region, always have a rib attached and a spine on top “True ribs” Directly attached to sternum with cartilage “False ribs” Connect to each other with cartilage, not the sternum “Floating ribs” Seen in the dog, have cartilage on the tips but do not attach to anything

Lumbar Vertebrae of the lower back Carnivores tend to have more – greater flexibility Herbivores need to have short, strong back to support large digestive and reproductive organs

Sacral Vertebrae of the pelvic region Fused together on the ventral side Herbivores generally have more to add strength & support to the back. Carnivores less for flexibility

Coccygeal Vertebrae of the tail region Used for balance Become smaller at the end of the tail

Appendicular Skeleton The fore and hind limbs Forelimb Scapula- shoulder blade attached with muscle Clavicle Cat is the only domestic animal with a clavicle Humerus Forms the upper arm Ulna Forms the elbow joint, fused with the radius in herbivores

Appendicular Skeleton Forelimb Radius- forms the forearm Carpus Commonly called the “knee” in horses, the “wrist” in dogs and humans Metacarpals- commonly called the cannon region of the forelimb

Appendicular Skeleton Metacarpals Number depends on species: Humans: 5 Horses: 1 plus 2 accessory metacarpals, called splint bones Dogs & Cats: 4 plus the dewclaw Cattle: 1 that splits at bottom into a cloven hoof & 2 dewclaws Pigs: 4 (2 toes & 2 dewclaws)

Appendicular Skeleton Forelimb Proximal phalanx (P1) Bones of the finger, hoof, and claw Intermediate phalanx (P2) Distal phalanx (P3) The coffin bone in horses Proximal sesamoids Tucked in behind P1 Distal sesamoid Tucked in underneath P3

Appendicular Skeleton Hind Limb Pelvis Tuber coxae-part of pelvis that forms the “point of hip” Ischiatic tuberosity-part of pelvis that forms the “seat bones” Femur Patella Forms the “stifle” joint in horses, knee in dogs or humans Tibia Main bone of the gaskin of the horse

Appendicular Skeleton Hind Limb Fibula Fused with the tibia & considered vestigial in herbivores Tarsus Commonly called “hock” Human ankle Metatarsal Cannon region in the hind limb. Number depends on species P1 P2 P3 Proximal & distal sesamoids

Axial and Appendicular Skeleton Axis Vertebrae Skull Cervical Sacral Thoracic Lumbar Coccygeal Atlas Scapula Pelvis Femur Patella Humerus Ribs Olecranon Fibula Tibia Radius Tarsals Carpals Metatarsals Ulna Phalanges Phalanges Sesamoids Metacarpals

Classification of Bones Short Bone Cube shaped (carpus & tarsus) Flat Bone Plate of bone (scapula, rib, skull) Irregular Bone Complex shaped (vertebrae) Sesamoid Small, seed-shaped bone (proximal & distal sesamoids, patella) Long Bone Bone is longer than it is wide (femur, tibia, humerus)

Bone Anatomy Diaphysis Epiphysis Metaphysis Medullary Cavity Endosteum Body of a long bone Epiphysis Enlarged ends of long bones Metaphysis Joining point of diaphysis & epiphysis Medullary Cavity Space within bone filled with marrow Endosteum Thin inner protective layer lining the medullary cavity

Bone Anatomy Epiphysis Diaphysis Periosteum Medullary cavity Endosteum Bone marrow Metaphysis

Bone Growth Occurs in the epiphysis of long bones Epiphyseal growth plates produce cartilage, which gradually turns into bone via a process called ossification.

Fractures Simple Compound Complete Incomplete Bone does not break skin Bone breaks through skin, much more serious Complete Fracture goes completely across the bone. Incomplete Fracture does not go completely across bone.

Classifying Fractures Fissure fracture Incomplete break, along the long axis of the bone Greenstick fracture Incomplete break on one side of a bone, usually due to a bending force Transverse fracture Break across the bone Comminuted fracture Bone shatters into many pieces

Bone Fractures Fissured Greenstick Transverse Comminuted