2Skeletal SystemBony tissues that form the body’s framework comprise the Skeletal System.In domesticated animals, the skeletal system is internal, called an endoskeleton, and are basically alike in most species.
3Skeletal SystemThe number of bones in a horse’s neck are the same as those in a rabbit’s, but the size and length vary.
4Skeletal SystemThe outer layers of bones are composed of hard mineral deposits. About 26% of total bone mass is composed of mineral matter.The remainder of the composition of bones includes 20% protein, 4% fat, and 50% water.
5Skeletal System About 85% of the mineral matter is calcium phosphate. The remaining 15% is calcium carbonate.
6Skeletal SystemThe inner core of bones is soft tissue called bone marrow.Some of the bone marrow consists of yellow fat, called yellow marrow.The other portion is made of red tissue called red marrow, that is responsible for red blood cell formation.
7Skeletal SystemAs an animal grows, bones increase in size and length in the region of cartilage between the end and shaft of bones.As the animal matures, this cartilage ossifies (becomes bony material).
8Skeletal SystemIn mature animals, bone is continually being reabsorbed and replaced, but no new bone growth occurs.Osteoporosis occurs when the bone that is reabsorbed is not replaced.
9Skeletal SystemAs long bones grow in length, they also increase in diameter.This is caused by the production of new bony tissue in the periosteum that surrounds the outside of the bone.
10Skeletal SystemBone growth is affected by hormones, vitamins, and other nutrients.Therefore, bones can become fragile or distorted due to nutritional deficiencies.Breaks in bones repair when the ends fill with a fibrin clot, that becomes bony tissue.
11Skeletal SystemThe skeletal system provides body support and leverage for muscle movement, which is made possible by several types of joints.
12Skeletal SystemBall-and-socket joints can move in all directions (shoulder).Hinge joints move in only two directions (knee).Pivot joints allow for movement in several directions (neck)
13Skeletal SystemGliding joints allow for flexibility to move forward, backward, or sideways (vertebrae)
14Skeletal SystemJoints are held together by ligaments and are enclosed by a capsule which contains synovial fluid to lubricate the joint and allow friction-free movement.
15Skeletal SystemThe skeletal system of animals of the phylum Chordata can be divided into three parts:the axial (spine, ribs, sternum, skull)the pectoral limb (foreleg)the pelvic limb (pelvic girdle and hindlegs)
23Skeletal SystemBones are divided into four classes based on their shape and function:Long bones (support)Flat bones (muscle attachment and organ protection)Short bones (help in movement and change the direction of tendons)Irregular bones (vertebrae)
24Skeletal System Parts of the skeletal system protect vital organs. Skull (protects the brain)Rib cage (protects the heart, lungs, and certain abdominal organs)Vertebrae (protect the spinal column)