SKELETAL SYSTEM REVIEW

The Skeleton Comprised of 206 bones Function: –SUPPORT - framework of body –PROTECTION - Protects vital organs –LEVERAGE - Works with muscular system in movement –STORAGE - of minerals and fats –HEMATOPIESIS - Red blood cell development

Axial Skeleton Consists of: –SKULL Eight cranial bones 14 bones of face –SPINAL COLUMN –RIBS –STERNUM

Appendicular Skeleton Consists of: (Appendages) –ARM bones –LEG bones –SHOULDER GIRDLE –PELVIS Two pelvic bones –Formed of three fused bones Ilium –Large, flared upper bone

Spinal Column 26 vertebrae divided into 5 regions: –Cervical –Thoracic –Lumbar –Sacrum –Coccyx Between vertebrae –Disks of cartilage Add strength and flexibility

Bone Formation Bones formed from cartilage 3 types of bone cells –OSTEOBLASTS = produce bone –OSTEOCYTES = m ature bone cells –OSTEOCLASTS = breakdown bone

Structure of a Long Bone DIAPHYSIS = shaft of compact bone tissue –Yellow bone marrow located inside medullary cavity EPIPHYSIS = ends of spongy bone tissue –Contains red bone marrow PERIOSTEUM = thin layer of fibrous tissue covering outside of bone –Nourishes and protects bone –Generates new bone cells for growth and repair

Joints (articulations)- when 2 bones come together Classified by amount of movement they allow –SYNARTHROSIS = immoveable joint (Example: Sutures of the skull) –AMPHIARTHROSIS = slightly moveable joint –DIARTHROSIS (Synovial joint) = freely moveable joint (Contain synovial fluid which acts as a lubricant to allow for free movement)

Movement at Joints Flexion…..movement reducing the angle between articulating bones Extension…..movement increasing the angle between articulating bones Abduction…..Movement away from the longitudinal axis of the body Adduction….Movement toward from the longitudinal axis of the body Circumduction….Movement forms a cone such as hip and arm circles Rotation…Movement is around the longitudinal axis of the limb or body

Ossification & Growth OSSIFICATION ………The formation of bone –Formation of bones begins in the fetus from a hyaline cartilage model (endochondral ossification) –BONE GROWTH….. Some bones continue to grow until age –EPIPHYSEAL PLATES…. plates in long bones containing actively growing cartilage that is constantly being converted to bone (endochondral growth). –The epiphyseal plate closes in the adult and there is no more growth in length. –Appositional growth……bones also must grow in diameter, this occurs by osteoblast activity under the periosteum

Growth in Bone Length

Bone Remodeling Bone is constantly changing tissue. It is constantly breaking down or building up in response to mechanical stress and hormones Mechanical stress……causes more bone creation The hormones are attempting to maintain a constant blood calcium level

Hormones PARATHYROID HORMONE …..is released in response to low blood calcium. Parathyroid hormone stimulates osteoclasts to break bone down, hence raising blood calcium levels. CALCITONIN from the thyroid gland is released in response to high blood calcium and its effect is to decrease osteoclastic activity, thereby lowering blood calcium. BONES ARE THE CALCIUM BANK OF THE BODY. BOTH, THE NERVOUS AND THE MUSCULAR SYSTEM NEED CALCIUM

Aging & the Skeletal System Reduction of bone mass begins in one’s thirties About 3% of the bone mass is lost per decade Bone loss is more pronounced in women –Post-menopausal osteoporosis….Occurs when a female’s menstrual and ovarian cycle stops –Estrogen levels diminish greatly causing her osteoclasts to be more active which triggers a loss in bone mass –Increased calcium intake, and exercise are helpful. Hormone replacement is often implemented

Clinical Aspects of the Skeleton INFECTIONS –OSTEOMYELITIS = inflammation of bone Caused by pus-forming bacteria –TUBERCULOSIS FRACTURES = break in bone usually caused by trauma Effects depend on location & severity Closed fracture (skin not broken) Open fracture (accompanied by skin wound)

Types of Fractures

Metabolic Bone Diseases OSTEOPOROSIS = loss of bone mass –Most susceptible: Women over 50 Possible prevention –Adequate calcium intake & weight-bearing exercises OSTEOMALACIA = softening of bone tissue –Possible causes: Deficiency of vitamin D Renal disorders Liver disease Certain intestinal disorders PAGET DISEASE (osteitis deformans) –Disorder of aging –Bones overgrown and thicker, usually involves bones of axial skeleton

RICKETS –Children's form of osteomalacia –More detrimental due to the fact that their bones are still growing. –Signs include bowed legs, and deformities of the pelvis, ribs, and skull.

Neoplasms Osteogenic sarcoma = highly malignant tumor Chondrosarcoma = cartilage tumor Signs of bone tumors –Pain –Easy fracture

Arthritis Joint inflammation –Most common form is osteoarthritis Joint cavity narrows Bone thickens Cartilage may crack and break loose Treatment –Analgesics –Anti-inflammatory agents –Physical therapy

Rheumatoid Arthritis Systemic inflammatory disease of joints –Cause may involve immunologic reactions –Overgrowth of synovial membrane –Synovial fluid accumulates, causes joint swelling –Degeneration of bone eventually causes ankylosis Treatment –Rest –Physical therapy –Analgesics –Anti-inflammatory drugs

Gout Increased uric acid in blood causes salt deposits in joints May result from –Metabolic disturbance –Secondary effect of another disease Treatment –Drugs Supress formation of uric acid Increase elimination of uric acid

Herniated Disk Central mass of intervertebral disk protrudes into spinal column Commonly occurs: –Lumbosacral region –Cervical regions Results from injury or heavy lifting Severe cases may require disectomy

Infants born with spina bifida are typically paralyzed distal from the defect.