Skeletal System 25 Skeletal system internal framework of

Skeletal System

25. Skeletal system – internal framework of the body A. Includes – bones, cartilage, joints

Function a. support

Function b. protection

Function c. movement

Function d. Mineral storage

Function e. Blood cell formation

C. Bone classification – based on shape

a. Long bones – longer than they are wide • Examples – arm and leg bones, phalanges

b. Short bones – roughly cube shaped • Examples – wrist and ankle bones, patella

c. Flat bones – thin, flattened, usually a bit curved • Examples – sternum, scapulae, ribs, skull

d. Irregular bones – complicated shapes • Examples – vertebrae, hip bones

Long Bone Structure

a. Periostium – nutrient rich membrane surrounding the bone

Periostium • Allows good attachment of tendons and ligaments

Periostium • Contains osteoblasts and osteoclasts

Periostium • Causes width growth

b. Epiphyses – enlarged ends of the bone

Epiphyses • Lined with compact bone and filled with spongy bone

Epiphyses • Ends covered with cartilage for cushion

Epiphyses • Red marrow - blood producing tissue found in spongy bone

Bone Marrow Donation

c. Epiphyseal plate – point where epiphysis and diaphysis meet

Epiphyseal plate • Disk of cartilage where growth occurs during childhood

Epiphyseal plate • Direction of growth is toward the shaft Your growth in height is likely to stop by the time you are 16 if you're a girl and 18 if you're a boy

d. Diaphysis – tubular shaft

Diaphysis • Lined with thick collar of compact bone

Diaphysis • Medullary cavity – hole in the center that contains yellow bone marrow (fat for energy storage)

Surface Features a. Projections b. Depressions c. Openings

Projections a. For attachments

Depressions b. For joints to fit together

Openings c. For blood vessels and nerves

Osseous Tissue

a. Osteon – a group of round tubes

b. Central canal – contain blood vessels and nerve fibers

c. Lamellae – each ring

d. Lacuna – cavities between each lamellae, contain osteocytes

Lacuna

e. Osteocytes – mature bone cells

Two other types of osteocytes • Osteoblasts – build bone • Osteoclasts – consume or destroy bone

Bone Formation

Fetal skeletons • Fetal skeletons are made of cartilage. By the time they are born, much of the cartilage has been replaced with bone. • Cartilage continues to be replaced until a person is about 25 years old.

Bone remodeling G. Osteoclasts circulate throughout the bone and look for old or damaged tissue to break down, which are then replaced by osteoblasts which lay down new bone tissue.

Issues with Bones

Breaks or fractures a. Greenstick – doesn’t completely break through the bone (incomplete) • Common in young children

Breaks or fractures b. Spiral – diagonal break from twisting force • Common sports fracture

Breaks or fractures c. Comminuted – fragments into 3 or more pieces • Common in elderly - brittle bones

Breaks or fractures d. Transverse – cuts straight across the axis of the bone

Breaks or fractures e. Compound – breaks through the skin

Breaks or fractures f. Compression – bone is crushed

What type of fracture?

What type of fracture?

What type of fracture?

What type of fracture?

What type of fracture?

What type of fracture?

Fracture Repair

Step 1 a. A hematoma forms over the fracture site

Step 2 b. Fibro cartilaginous callus formation

Step 3 c. Bony callus formation

Step 4 d. Bone remodeling

Osteoporosis C. Deterioration of the bones – bones absorption outpaces bone deposit