Bone anatomy and development

Question 1

what are the four basic types of bones? (make examples)

Answer 1

short, flat, irregular, and long bones

Question 2

where are the periosteum and endosteum located?

Answer 2

periosteum = is found on the outer surface of bone 
endosteum = lines the medullary cavity

Question 3

what types of cells are found in the periosteum and endosteum?

Answer 3

osteoblasts, osteoclasts, osteochondral progenitor cells

Question 4

what is the function of perforating (sharpey) fibers?

Answer 4

used to attach muscle to the periosteum of bone by merging with the fibrous periosteum and underlying bone as well.

Question 5

where is red and yellow bone marrow located in a child and an adult?

Answer 5

in children = medullary cavity is red marrow

in adult = red marrow is replaced by yellow in limb bones; elsewhere varying portions of yellow/red marrow are found

Question 6

compare the structure of a long bone with those of flat, short, and irregular bones. Explain where compact and spongy bones are found in each type

Answer 6

Flat bones = interior framework of spongy bone sandwich between 2 layers of compact bone
short bones = no diaphyses and not elongated
irregular bones = compact bone surrounds spongy bone center; similar to structure of epiphysis of long bones

Question 7

diaphysis

Answer 7

shaft; primarily compact bone

Question 8

epiphysis

Answer 8

end of the bone; primarily spongy bone

Question 9

periosteum

Answer 9

outer, double-layered connective tissue membrane with ligaments and tendons attached to bone through the periosteum; blood vessels and nerve pathways; the periosteum is where one grows in diameter

Question 10

endosteum

Answer 10

thin connective tissue membrane lining the inner cavities of bone

Question 11

articular cartilage

Answer 11

thin layer of hyaline cartilage covering a bone where is forms a joint (articulation) with another bone

Question 12

epiphyseal plate

Answer 12

growth plate; hyaline cartilage; present until growth stops

Question 13

spongy bone

Answer 13

bone having many small spaces; found in epiphysis; arranged into trabeculae

Question 14

compact bone

Answer 14

dense bone with few internal spaces organized into osteons; forms the diaphysis and covers the spongy bone of the epiphysis

Question 15

medullary cavity

Answer 15

large cavity within the diaphysis

Question 16

red marrow

Answer 16

connective tissue in the spaces of spongy bone or in the medullary cavity; the site of blood cell production

Question 17

yellow marrow

Answer 17

fat stored within the medullary cavity or in the spaces of spongy bone

Question 18

describe the formation of spongy and compact bone during intramembranous ossification

Answer 18

spongy bone = osteoblasts come together on the trabeculae and produces bone, which causes the trabeculae to become bigger and longer; spongy bone forms as trabeculae join which allows interconnected network of trabeculae separated by spaces
compact bone = osteoblasts from the periosteum lay down bone matrix to form an outer surface of compact bone

Question 19

what are centers of ossification?

Answer 19

the locations in the membrane where ossification begins

Question 20

what are fontanels?

Answer 20

soft spots; larger membrane covered spaces between the developing skull bones that have not yet ossified; usually close at the age of 2

Question 21

describe the process of endochondral ossification

Answer 21

chondroblasts make a cartilage model surround by perichondrium (except where joints will form) –> perichondrium becomes the periosteum and bone collar is produced; chondrocytes, hypertrophy, calcified cartilage forms –> primary ossification center forms; blood vessels and osteoblasts invade calcified calcium; osteoblasts lay down bone matrix forming spongy bone. –> secondary ossification form in the epiphyses of long bones –> in mature bone, epiphyseal plate becomes a line and all cartilage becomes bone (except articular cartilage)

Question 22

when do primary and secondary ossification centers appear during endochondral ossification?

Answer 22

Primary ossification center = forms in the diaphyseal region of the periosteum called the periosteal collar. Secondary ossification centers = develop in the epiphyseal region after birth.

Question 23

epiphyseal line

Answer 23

bone stops growing in length

Question 24

perichondrium

Answer 24

CT covering over cartilage, except at articulations

Question 25

periosteum

Answer 25

CT membrane cover outer surface of bone

Question 26

osteocyte

Answer 26

maintain matrix

Question 27

osteoclasts

Answer 27

break down matrix for reabsorption

Question 28

intramembranous ossification

Answer 28

flat bones - ribs, scapula, pelvis, skull; takes place in CT membrane

Question 29

endochondral ossification

Answer 29

most bones in the body-long bones; takes place in cartilage