Chapter 6 Skeletal System

red bone marrow

site of hematopoiesis; in adults located in all spongy bone

Diaphysis

shaft of a long bone

proximal epiphysis

the end of the bone located nearest to the midline of the body

distal epiphysis

end of the bone located farthest away from the midline

medullary cavity

central, hollowed-out area in the shaft of a long bone

compact bone

Hard, dense bone tissue that is beneath the outer membrane of a bone, found in diaphysis

articular cartilage

covers the surfaces of bones where they come together to form joints

spongy bone (cancellous bone)

mesh-like bone tissue found in the interior of bones, and can be found at the epiphysis

Periosteum

A dense, vascular, fibrous membrane covering the surface of bones and serving as an attachment for tendons and muscles.

yellow bone marrow

Stores fat, found in medullary cavity of adult bones

epiphyseal plate

structure composed of hyaline cartilage where longitudinal growth takes place in the growing skeleton

Endosteum

inner membrane that lines the medullary cavity and trabeculae of spongy bone

comminuted fracture

fracture in which the bone is splintered into 3 or more pieces

displaced fracture

bone ends are out of normal alignment

greenstick fracture

bending and incomplete break of a bone; most often seen in children

incomplete fracture

bone is not broken all the way through

spiral fracture

a fracture in which the bone has been twisted apart

axial skeleton

Portion of the skeletal system that consists of the skull, rib cage, sternum, and vertebral column

appendicular skeleton

The portion of the skeleton that attaches to the axial skeleton and has the limbs attached to it

Functions of bones

support, protection, movement, storage, blood cell formation

Hematopoiesis

blood cell formation

Two basic types of bone tissue

compact bone and spongy bone

Classification of bone shapes

long bones, short bones, flat bones, irregular bones

Osteoblasts

bone forming cells

Osteocytes

mature bone cells

Osteoclasts

Bone-destroying cells

parathyroid hormone (PTH)

raises blood calcium level when the calcium levels are too low, inhibits osteoblasts and stimulates osteoclast to work

osteon

A structural unit of compact bone consisting of a central canal surrounded by concentric lamellae of matrix.

fibrocartilage

cartilage located in pubic symphysis, menisci of knee, and intervertebral discs

canaliculi

tiny channels that radiate from lacunae; contain cytoplasmic projections of osteocytes for diffusion of nutrients

epiphyseal fracture

a break at the location of the growth plate, which can affect growth of the bone

endochondral ossification

process of creating bone from from the inside of a cartilage model

3rd step of endochondral ossification

the periosteal bud invades the internal cavities and spongy bone formation begins as primary ossification center

hydroxyapetite

a crystalline mineral compound of calcium and phosphorous that make up bone

wolff's Law

A bone grows or remodels in response to forces or demands placed upon it

elastic cartilage

flexible cartilage located in the ear and epiglottis

compression fracture

a fracture in which the bone is crushed; common in the vertebral column

intramembranous ossification

process by which bone forms within/between two membranes such as in the clavicles and skull bones

lamellae

rings around the central canal, sites of lacunae

depression fracture

broken bone portion is pressed inward

fibrocartilagenous callus formation

2nd step of fracture repair

flat bones

examples are sternum, ribs, parietal bones

short bones

examples are carpals and tarsals

irregular bones

examples are coxal bones, vertebrae, scapula

long bones

examples are femur, tibia, radius

organic components

the portion of bone that makes it flexible

inorganic components

calcium phosphate (hydroxyapetite) crystals provide strength and make bone hard