Honors Anatomy & Physiology

A. Supporting connective tissue 1. Matrix- Contains numerous fibers & in some cases, insoluble salts B. Cartilage – Support, framework, model for developing bone 1. Chondrocytes – cartilage cell 2. Matrix- firm gel containing chondroitin sulfates 3. Hyaline cartilage a) Flexible- closely packed collagen fibers b) Location (1) Ends of bones involved in movable joints (2) Connections between ribs and sternum

4. Elastic cartilage a) Elastic fibers- Dense network; more flexible than hyaline cartilage b) Location – outer ear, tip of nose

5.Fibrocartilage a) Collagen fibers- Very high concentration; shock absorbtion b) Location- Intervertebral discs, between knees, pelvic girdle

6. Lacks direct blood supply a) Slow to heal b) Blood supply comes from connective tissue covering → perichondrium

C.Bone 1. Osteocyte – bone cell 2. Matrix – Collagen fibers plus calcium salts

A. 206 bones of the skeleton can be grouped into two divisions 1. Axial Skeleton a) Skull b) Vertebral column c) Thorax 2. Appendicular Skeleton a) Appendages b) Structures by which appendages are attached to the axial skeleton

III. Functions of the Skeletal System A. Support – framework for the body B. Protection – protection for soft tissues and organs C. Movement - attachment for skeletal muscles D. Hematopoiesis – blood cell production E. Storage of minerals (calcium & phosphorous) and lipids

IV. Macroscopic Structures of the Bone A. Types of bones 1. Long bones – longer than they are wide e.g. femur 2. Short bone – roughly cube-shaped e.g. carpal, tarsal 3. Flat bones – thin, flat & often curved e.g. sternum, ribs, skull 4. Irregular bones – odd shapes e.g. os coxa, scapula, vertebrae

B. Structure of a typical long bone 1. Diaphysis – the shaft or body 2. Epiphysis – the end 3. Metaphysis – the junction of diaphysis and epiphysis 4. Medullary cavity – area within the diaphysis 5. Periosteum – connective tissue on the outer portion; contains blood vessels 6. Endosteum - connective tissue lining the medullary cavity 7. Articular cartilage – hyaline cartilage on the ends of the epiphysis

A. Osteoblasts: Bone building, bone repairing cells in the periosteum B. Osteocytes: Mature bone cells within the bone matrix (lacunae) C.Osteoclasts: Bone destroying cells – causes reabsorption of bone

A. Compact Bone 1. Location and distribution – 80% of total bone mass a) On the outer surface of all bones – smooth, white appearance b) Makes up most of the diaphysis of long bones

2. Structure a) Very dense, stress-bearing b) Haversian System = Osteon (1) Haversian canal (osteonic canal) – carries nutrients and wastes to and from the osteocytes (2) Lamellae: concentric cylinder –shaped calcified structure (3) Lacunae – small spaces containing osteocyte (4) Osteocyte – Bone cell that facilitates exchange of calcium between blood and bone

(5) Canaliculi – canals connecting the lacunae together and to the Haversian canal

Haversian System (Osteon)

c) Nutrient foramen – opening in bone that allows passage of blood vessels and nerves d) Matrix – calcium and phosphorous salts e) Yellow marrow – Medullary cavity of long bones - fat storage

B. Cancellous Bone – Spongy Bone 1. Location and distribution a) The inner surface of all flat, irregular, and short bones b) The epiphysis of long bones 2. Structure - Trabeculae a) Porous – No Haversian systems b) Contains blood vessels c) Red marrow – contains blood- forming cells

A. Endochondral Ossification: Long Bone Growth 1. Embryo at 6-8 weeks has hyaline cartilage skeleton – mostly appendicular skeleton 2. At 8-12 weeks blood vessel invades perichondrium a) Changes nutrition of chondrocytes (cartilage is avascular!) b) Chondrocytes respecialize into osteoblasts 3. Osteoblasts lay down layer of compact bone around diaphysis = bone collar

4. Chondrocytes starve, die and hypertrophy (swell up) a) Release alkaline phosphatase b) Causes Ca 2+ salts to be deposited and form a weak spongy bone 5. Blood vessels, nerves, osteoblasts, osteoclasts and red bone marrow invade the bone and move to center of diaphysis a) Known as Periosteal Bud b) Sets up the Primary Ossification Center (POC)

6. Primary Ossification Center (POC) sets up “shop” a) Osteoclasts begin to eat weak spongy bone from dead cartilage, forming the medullary cavity b) Ossification center begins to move towards the epiphysis – “The Chase” 7. Bone grows in length as POC chases growing cartilage

8. Secondary Ossification Centers (SOC) begin to form at the epiphysis (around birth) a) Different from POC in that osteoclasts do not eat spongy bone – instead, weak spongy bone is remodeled and strengthened b) Grows toward diaphysis TRAPPING the cartilage c) Known as epiphyseal growth plate 9. Growth hormone from pituitary gland stimulates this band of cartilage to become mitotic – results in bone growth (Length)

10. Sex hormones can also influence rapid growth – ie. Growth spurts during puberty 11. When growth hormone levels fall – POC meets SOC and they form the epiphyseal line – growth in length is over

12. Growth in Diameter of Long Bone a) Endosteum contains packets of osteoclasts b) Periosteum contains packets of osteoblasts c) Stress on Bones (1) Pull of muscles and amount of weight carried puts stress on bones (2) Areas of bone that receives more stress stimulates osteoblasts to lay down more bone (3) Stress determines WHERE the bone will remodel

d) Calcium levels of the blood (1) Must be between mg/100mL of blood for proper nervous and muscle tissue function (2) Calcitonin (thyroid) lowers blood calcium levels by stimulating osteoblasts to build bone (3) Parathyroid Hormone (PTH) raises blood calcium levels by stimulating osteoclasts to remove calcium salts from bone matrix and place it into blood

(4) Hormones determine WHEN the bone remodels PTHCALCITONIN Osteoclasts Osteoblasts ↑ Ca 2+ Levels ↓ Ca 2+ Levels in blood in blood Ca 2+ Levels 9-11 mg/100 mL blood

B. Intramembranous Ossification 1. Flat bones (skull) and some irregular bones 2. Cells within the middle of the tissue respecialize into osteoblasts and cluster together 3. Osteoblasts secrete bony matrix around the collagen fibers and form ossification center- -Trabeculae are formed. 4. Periosteum forms on the outside of the fibrous membrane and produces compact bone 5. Ossification center moves outward in all directions until the cartilage is completely ossified

A. Fracture Type 1. Simple fracture – no damage to other tissue 2. Compound fracture – break in the skin 3. Comminuted fracture – number of parts 4. Impact fracture – driven into each other 5. Spiral fracture – twisted apart (torque) 6. Greenstick fracture – partial break (young bone)

B. Healing of Fractures 1. Realignment of bones – Reduction a) Open Reduction – surgery required to realign bones (screws, plates, or rods may be needed) b) Closed Reduction – No surgery needed 2. Hematoma forms around the broken ends of bone

3. Fibrocartilage callus formation a) Break bridged with fibrocartilage b) Stabilizes broken ends and sets up ossification 4. Ossification a)Cartilage converted into bone 5. Healing time depends on fracture type, age of patient 6. Remodeling a) Denser matrix of bone kept where break occurs b) Gives extra strength to this area

A. Function 1. Muscle and ligament attachment 2. Form joints

Every bump, groove, and hole has a name on your bones

 Two types of bone markings:  Projections (aka processes) that grow out from the bone  Depressions (cavities) that indent the bone

 1) Condyle: Rounded articular projection Condyle

 2) Head: bony expansion on a narrow neck  3) Facet: smooth, nearly flat articular surface

 4) Ramus: Armlike bar of bone

1) Crest: Narrow ridge of bone (Line: smaller than a crest) 2) Epicondyle: Raised area on or above a condyle ULNA

3) Tubercle: Small rounded projection 4) Tuberosity: large rounded or roughened projection 5) Trochanter: very large, blunt projection (only on femur) Proximal Tibia

6) Spine: Sharp, pointed projection Thoracic Vertebrae

 Allow blood vessels or nerves to pass through. 1) Meatus: (me - A- tus) Canal or tube

2) Fossa: shallow basin 3) Fissure: narrow, slit- like opening

4) Sinus: Cavity within a bone; filled with air and lined with mucous membranes 5) Foramen: Round or oval opening Foramen Magnum

6) Sulcus, Groove or Furrow: a shallow depression

Projections 1) Condyle 2) Head 3) Facet 4) Ramus 5) Crest 6) Epicondyle 7) Tubercle 8) Tuberosity 9) Trochanter 10) Spine Depressions 1) Meatus 2) Fossa 3) Fissure 4) Sinus 5) Sulcus or Groove or Furrow