Osteology Exam

Directional Terms, Osteology, Body Planes

Osteology

The study of bone structure and the treatment of bone disorders

Functions of the Bone

Support, Protection of internal Organs, Movement, Mineral Storage, Storage of energy + lipid in yellow marrow, blood cells production in red marrow

Bone Matrix consist of:

25% Water, 25% protein fibers, 50% mineral salts, bone cells

Characteristics of Bone Matrix

Hardness and Tensile Strength

Calcification

Mineral Salts (Calcium phosphate and calcium carbonate) crystallizes around collagen fibers, hardening the matrix

Tensile Strength

Collagen fibers reinforces the matrix, making the bone flexible and brittle

Osteoprogenitor Cells

Unspecialized precursor cells that form osteoblasts; found in periosteum and endosteum

Osteoblasts

Immature bud cells that form bone; build bone tissue matrix (collagen and minerals)

Osteocytes

Mature bone cells; maintain daily cell activities of bone tissues

Osteoclasts

Develop from white blood cells; aid in the destruction of the matrix (collagen and minerals)

Cancellous Bone

Make up tissue in short, flat, irregularly shaped bones and Epiphysis of long Bone; stores red bone marrow and provides support; made up of trabeculae

Structure of Trabeculae

Arranged in an irregular latticework of thin columns of bone, spaces between are filled with red marrow, canaliculi connect to the periosteum, osteocytes not buried deeply- osteons are not necessary.

Compact Bone

found in external layers of all bones and make up the diaphysis of long bones; provides protection and support, helps long bone resist the stress of weight, made up of osteons.

Structure of Osteon

Consists of concentric lamellae, lacunae, canalliculi, haversian and volkmann’s canals.

Volkmann’s Canal

Runs horizontally through bone; allows the passage of blood vessels and nerves that penetrate from the periosteum.

Haversian Canal

Run vertically (longitudinally) through the bone; connects the blood vessels and nerves of the periosteum with those of the medullary cavity.

diaphysis

central shaft

epiphysis

end of long bones

metaphysis

region where diaphysis joins the epiphysis

Articular Cartilage

thin layer of hyaline cartilage that covers the end of bones

periosteum

thick double layered membrane covering bone

outer fibrous layer

contains blood vessels, lymph, nerves

inner elastic layer

contains blood vessels and bone cells

Function of Periosteum

helps bone to grow in diameter, protects the bone, repairs, nourishes, and serves as an attachment for ligament and tendons.

Medullary Cavity

Central cavity, containing yellow marrow

Endosteum

thin membrane lining medullary cavity

Ossification

embryonic connective tissue (fibrous and cartilage) hardens into bone; begins the 6th week into utero and continues into adulthood

Intramembranous Ossification

occurs directly within fibrous connective tissue; osteoprogenitor cells develop into osteoblasts; occurs in flat bones of skull and lower jaw

Endochondral Ossification

occurs within hyaline cartilage tissue; cartilage becomes calcified from inside out, remains on articular surfaces; occurs in most bones and long bones

Nutrient Artery

blood vessels that enter the bone threw the periosteum

Remodeling

the replacement of old, worn, or injured bone tissue

Calcium, Phosphorus, Magnesiums; Vitamins A, B12, C, and D; Hormones: Human Growth Hormone, Testosterone, Insulin, Thyroxine

Normal bone growth requirements

Mechanical Stress

Affected by muscle work and gravity

Weakened bone and reduced denisty

Removal of stress causes:

Increased bone density

Exercises such as walking and weight lifting will:

Mechanical stress, increasing mineral deposition, and production of collagen fibers

Bone strength depends on

Demineralization

loss of calcium and other minerals from matrix

30; accelerates at around 45 while estrogen levels decrease

beginning of demineralization in females:

45

beginning of demineralization in males:

Decrease in protein synthesis

reduces collagen production; bone loses tensile strength, causing it to become more brittle

Osteoporosis

loss of calcium, bone becomes less dense

Ricketts

bone becomes too flexible; vitamin D deficiency

Paget’s Disease

abnormal acceleration of the remodeling process

Osteosarcoma

bone cancer; this makes bone more brittle

Scoliosis

sideways curvature of the spine that occurs mostly during growth spurts

Superior (cranial)

toward the head/upper part of the structure of the body; above

inferior (caudal)

away from the end/toward the lower part of the body; below

anterior (ventral)

toward the front of the body; in front of

posterior (dorsal)

toward the back of the body; behind

medial

toward the midline of the body

lateral

away from the midline of the body

proximal; for limbs

closer to the origin (point of attachment) of the trunk of the body

distal; for limbs

farther from the origin (point of attachment) of the trunk of the body

superficial

toward the body surface

deep

away from the body surface; internal

transverse section

1

(mid) sagittal section

2

coronal section

3

oblique

diagonal cut -no pic :(-

Axial

Division of skeletal system containing skull, vertebrae, and thorax (chest)

Appendicular

Division of skeletal system containing bones, upper & lower extremities, including the shoulder and pelvic girdle