The Skeletal System

Axial skeleton: long axis (skull, vertebral column, rib cage) Appendicular skeleton: limbs and girdles

Appendicular Skeleton Axial Skeleton Appendicular Skeleton Cranium (skull) Mandible (jaw) Vertebral column (spine) Cervical vertebrae Thoracic vertebrae Lumbar vertebrae Sacrum Coccyx Sternum (breastbone) Ribs Clavicle (collarbone) Scapula (shoulder blade) Coxal (pelvic girdle) Humerus (arm) Radius, ulna (forearm) Carpals (wrist) Metacarpals (hand) Phalanges (fingers, toes) Femur (thigh) Tibia, fibula (leg) Tarsal, metatarsals (foot) Calcaneus (heel) Patella (knee)

Functions of the Bones Support body and cradle soft organs Protect vital organs Movement: muscles move bones Storage of minerals (calcium, phosphorus) & growth factors Blood cell formation in bone marrow Triglyceride (fat) storage

Bone Structure Flat Bones – platelike structures with broad surfaces Examples: ribs, scapulae Irregular Bones – variety of shapes Examples: vertebrae, facial bones Long bones – long longitudinal axes and expanded ends Examples: forearm, thigh Short Bones – somewhat cubelike, with roughly equal lengths and widths. Examples: wrist/ankle bones

Parts of a Long Bones Epiphysis – end of a long bone Articular cartilage – covers the ends of bones in synovial joints Diaphysis – shaft of a long bone Periosteum – dense connective tissue covering the surface of the bone Compact Bone – dense bone tissue Spongy Bone – bone that consists of bars and plates separated by irregular spaces Trabeculae – branching, bony plates in marrow Medullary Cavity – cavity containing red or yellow marrow Endosteum – tissue lining the medullary cavity in a bone Marrow – connective tissue in spaces in bones

Adult = 206 bones Types of bone tissue: Compact bone: outer layer – dense & solid Spongy bone: inner layer - open spaces, marrow Features: Very hard (calcium salts) Light weight Ability to resist tension and forces (collagen fibers)

Spongy vs. Compact Bone

Bone Development and Growth Parts of the skeletal system begin to form during the first few weeks of prenatal development. Osteoblasts – bone-forming cells Osteocytes – osteoblasts surrounded by extracellular matrix Ossification – the formation of bone Most of the bones of the skeleton are endochondral bones

Epiphyseal plates

Epiphyseal plates

Bone function SUPPORT AND PROTECTION BODY MOVEMENT Bones and muscles interact as simple mechanical devise called levers.

Bone function cont. BLOOD CELL FORMATION Hematopoiesis – process of blood cell formation There are 2 types of marrow in the bone, yellow and red. Red marrow function in the formation of red blood cells Yellow marrow stores fat and is not active in blood cell formation STORAGE OF INORGANIC SALTS Bones store calcium, mostly in the form of calcium phosphate Bones also store small amounts of magnesium, sodium, potassium, and carbonate ions. Bones can accumulate harmful metals such as lead and radium

Skeletal organization Grab a textbook and turn to page 142 Use figure 7.9 to label the skeletal system worksheet

The Skull 2 bone types: Cranial – form the top, sides, and back of the skull Facial – form the face

“Soft spots” felt on an infant's skull are actually fontanelles Fibrous connective tissue that connect the incompletely developed flat bones

Skull Grab a textbook and turn to page 146 Use figure 7.12 to label the skull worksheet

VERTEBRAL COLUMN Vertebrae are classified into regions: Cervical – neck, 5 vertebrae Thoracic – upper/middle back, 12 vertebrae Lumbar – lower back, 5 vertebrae Sacrum – triangular structure, 5 fused vertebrae Coccyx – tailbone, 4 fused vertebrae Turn to page 151 in the textbook and use figure 7.17 to label the spine The vertebral column extends from the skull to the pelvis and forms the vertical axis of the skeleton. It is composed of many bony parts, called vertebrae, that are separated by masses of fibrocartilage called intervertebral discs

joints

joints Fibrous Joints – lie between bones that closely contact one another Examples: skull, tibia/fibula Cartilaginous Joints – joints connected by fibrocartilage. Allows limited movement Examples: vertebrae, first rib/sternum

Joints cont. Synovial Joints Ball-and-socket joint – shoulder, hip Most joints in the skeletal system are synovial joints, which allow free movement. Menisci – fibrocartilage that absorbs shock Bursae – fluid-filled sacs to aid in movement of tendons over bone Ball-and-socket joint – shoulder, hip Condylar joint – metacarpals, phalanges Gliding/Plane joint – wrist, ankle Hinge joint – elbow, phalanges Pivot joint – radius/ulna, spine Saddle joint - thumb

Joint disorders Sprains – overstretching or tearing the connective tissues, including cartilage, ligaments, and tendons, that are associated with a joint Bursitis – Overuse of a joint or stress on a bursa

Joint disorders cont Arthritis – inflamed, swollen and painful joints Rheumatoid arthritis – autoimmune disorder in which the immune system attacks the body’s healthy tissues. Osteoarthritis – degenerative disorder due to aging or a poorly healed injury, may also be inherited Lyme arthritis – caused by lyme disease

Fractures (Breaks) Classified by: Position of bone – nondisplaced (normal) or displaced (bone out of alignment) Completeness of break – complete (broken through) or incomplete Orientation to long axis of bone – linear (parallel to bone) or transverse (perpendicular to bone) If bone penetrates skin – open (compound) fracture or closed (simple) fracture

Bone fractures Greenstick fracture Fissured fracture

Bone fractures cont Comminuted fracture Transverse fracture

Bone fractures cont Spiral fracture Oblique fracture

Male vs. Female Bone Structure

Male vs. Female Bone Structure

Male vs. Female Bone Structure

Bone Structure: Gender Differences Male Skull Larger and heavier Forehead shorter Face less round Jaw larger Mastoid processes more prominent Male pelvic bones Heavier and thicker Obturator foramen and acetabula are larger and closer together

Bone Structure: Gender Differences Male pelvic cavity Narrower and longer Less roomy and more funnel shaped Male sacrum Narrower Sacral promontory projects forward Sacral curvature is less sharp posteriorly Male coccyx Less movable

Bones you will need to identify - Ribs - Metatarsals - Sternum - Humerus - Pelvic Girdle - Radius - Clavicle - Ulna - Femur - Carpals - Tibia - Metacarpals - Fibula - Phalanges - Tarsals - Patella - Scapula - Skull - Vertebrae - frontal bone - atlas - zygomatic bone - axis - parietal bone - cervical - temporal bone - thoracic - occipital bone - lumbar - sacrum fused - coccyx fused