Anatomy Long Bone/Grandma Grandpa Lab Quiz

epiphyseal (growth) plate

a region of cartilage between the epiphysis and diaphysis where lengthwise growth occurs.

once the growth plate closes…

cartilage is replaced by bone and an epiphyseal line may remain.

indicated the bone is no longer growing

fontanelles

allow flexibility during birth and accommodate rapid brain growth.

with age:

gradually close

meet at sutures; normal adult skulls do not retain the infant’s open fontanelles

bone is …

living tissue

osteoclasts …

break down old bone

osteoblasts …

build new bone

remodeling

• osteoclasts + osteoblasts processes

• bone formation and growth generally outpace generally outpace breakdown

• bone mass usually reaches its peak in early adulthood

bone remodeling

1. osteoclasts break down old bone

2. resorption pit is cleared

3. osteoblasts build new bones

4. new bone mineralizes

5. remodeled bone

osteoid

new bone matrix

mineralized bone

hard bone

normal (younger) ribs

• smooth

• rounded sternal ends

older adult ribs

• cup-shaped

• jagged sternal ends

pelvis

• ilium

• Ischium

• pubis

• pelvic girdle

• female = broader subpubic angle and wider, shallower pelvic cavity

• male = narrower subpubic angle and a deeper, narrower cavity

sacrum

female = shorter and wider

male = longer and narrower

coccyx

female = projects less anteriorly, leaving more room for the pelvic outlet

male = project more anteriorly

skull

female = smaller, more vertical forehead, smaller mandible

male = larger and more robust, larger mandible, more sloping forehead

wolff’s law

healthy bone adapts and remodels itself in response to the mechanical loads and stresses placed upon it.

• bones adapt to the mechanical stress placed on it

• decreased stress: immobilization / less use - bone becomes thinner and less dense

• normal stress: typical daily activity - bone maintains normal density and shape

• increased stress: athlete / weight bearing - bone becomes thicker and stronger.

osteoporosis

chronic bone disease that weakens bones, making them fragile, porous, and much more likely to break (fracture).