Ch 6, 4 Bone structure

Question 1

bone markings

Answer 1

bulges, depressions and holes serve as

• types of attachment for muscles, ligaments, and tendons
• joint surfaces
• conduits for blood vessels and nerves

Question 2

bone textures

Answer 2

compact bone–dense outer layer made up of osteons

spongy (cancellous) bone– inner core, honeycomb of trabeculae

Question 3

structure of a long bone

diaphysis shaft

Answer 3

• compact bone forms outer layer
• spongy bone forms inner core around medullary cavity
• medullary cavity in adults contains yellow marrow-fat

Question 4

long bone structure

epiphyses

Answer 4

–expanded ends
proximal-end towards main body mass
distal-end away from main body mass
–has spongy bone interior containing red marrow cavities

Question 5

epiphyseal line

Answer 5

remnant growth plate (cartilage line)

Question 6

articular cartilage

Answer 6

hyaline, on joint surfaces

protects bone ends

Question 7

periosteum membrane

Answer 7

connective tissue membranes encloses outside of bone
-has outer fibrous layers
-inner osteogenic layer-bone forming layer
-contains..
osteoblasts-bone forming cells
osteoclasts-bone destroying cells
osteogenic cells- stem cells

Question 8

endosteum membrane

Answer 8

delicate connective tissue membrane on inside surfaces of bone
-also contains osteoblasts and osteoclasts

Question 9

nutrient foramen membrane

Answer 9

(formina) openings in periosteum where blood vessels, lymph vessels and nerves enter bones

Question 10

sharpeys membrane

Answer 10

collagen fibers that attach periosteum to bone

Question 11

structure of short, irregular and flat bone

Answer 11

like a sandwich

• compact bone covered with periosteum on both surfaces
• spongy bone covered with endosteum in the center-spongy bone layer called diploe
• red bone marrow between the trabeculae

Question 12

location of hematopoietic tissue (red marrow)

Answer 12

in adults
-in trabecular cavities of heads of femur and humerous
-in trabecular cavities of the diploe of flat bones
-sternum and pelvis
in newborn infants
-in medullary cavities of long bones
-in all spaces of spongy bone

Question 13

osteogenic cells

Answer 13

stem cells in periosteum and endosteum that gives rise to osteoblasts
-un specialized

Question 14

osteoblasts

Answer 14

• bone forming cells
• divide by mitosis then specialize
• produces matrix

Question 15

osteocytes

Answer 15

• as matrix develops around the osteoblasts they mature into osteocytes
• mature bone cells trapped inside cavities in the bone called lacunae
• maintains the health of the bone

Question 16

osteoclasts

Answer 16

• unrelated to the other 3
• they are macrophages (WBCs) that break down (resorb) bone by secreting enzymes that break down the matrix and release minerals into the blood

Question 17

haversian system or osteon

histology of compact bone

Answer 17

lamellae-
weight bearing, column-like matrix tubes
produced by a ring of osteoblasts(like tree rings)
collagen fibers run in different directions in adjacent lamella–increases strength

Central (haversian) cord-
contains the blood vessels and cords

Question 18

perforating (Volkmann’s) canals

histology of compact bone

Answer 18

at right angles to the central canal

connects blood vessels and nerves of the periosteum and central canal

Question 19

lacunae

compact bone

Answer 19

small cavities that contain osteocytes

Question 20

canaliculi

compact bone

Answer 20

hair like canals that connect lacunae to each other and the central canal

Question 21

circumferential lamellae

compact bone

Answer 21

encloses whole bone

resist twisting force

Question 22

trabeculae

spongy bone

Answer 22

align along lines of stress

Question 23

spongy bone

Answer 23

• contain irregularly arranged lamellae, osteocytes and canaliculi
• contain capillaries in endosteum supply nutrients

Question 24

organic components

Answer 24

a. osteogenic cells, osteoblasts, osteocytes, osteoclasts
b. osteoid-organic bone matrix secreted by osteoblasts (35% of bone mass)
contains proteoglycans, glycoproteins and collagen fibers
c. provides tensile strength and flexibility
d. resists stretching and twisting

Question 25

inorganic compounds

Answer 25

a. hydroxyapatites (mineral salts)
b. 65% bone mass
c. Mainly calcium phosphate crystals
d. provides hardness and resistance to compression