chapter 6 part 3

Question 1

Endosteum

Answer 1

structure of the long bone
* Single cellular layer of C T that lines all internal spaces including cavities in spongy bone and
medullary cavity.
* Includes osteoblasts, osteoclasts , and osteochondral progenitor cells.

Answer 2

periosteum
perforating fibers
endosteum

Question 3

Flat bones

Answer 3

• No diaphyses, epiphyses.
• Sandwich of spongy between
  compact bone.

Question 4

Short and irregular bones

Answer 4

• Compact bone that surrounds spongy bone center; similar to structure of epiphyses of long bones.
• No diaphyses and not elongated.
• Some flat and irregular bones of skull have sinuses – air-filled spaces lined by mucous membranes.

Question 5

Intramembranous ossification.

Answer 5

bone development
* Takes place in embryonic connective tissue membrane.

Question 6

Endochondral ossification.

Answer 6

bone development
* Takes place in cartilage.
* Produce woven bone that is then remodeled.
* After remodeling, formation cannot be distinguished as one or other.

Question 7

Intramembranous ossification

Answer 7

Takes place in connective tissue membrane formed from
embryonic mesenchyme.
* Forms many skull bones, part of mandible, diaphyses of clavicles.
* Begins about the 5th week of embryonic development when embryonic mesenchyme condenses around the developing brain to form a membrane of C T with delicate, randomly oriented collagen fibers.

Question 8

Centers of ossification

Answer 8

locations in membrane where ossification begins.

Question 9

Fontanels

Answer 9

large membrane-covered spaces between
developing skull bones; unossified.

Question 10

Osteoblast formation

Answer 10

Some embryonic mesenchymal cells in the
connective tissue membrane differentiate into osteochondral progenitor cells which then form osteoblasts. The osteoblasts form bone matrix
which will surround the collagen fibers of the connective tissue membrane. Once they are embedded in bone matrix, the osteoblasts become osteocytes. As a result, many tiny trabeculae of woven bone develop

Question 11

Spongy bone formation

Answer 11

Additional osteoblasts gather on
the surfaces of the trabeculae and produce more bone,
thereby causing the trabeculae to become larger and longer. Spongy bone forms as the trabeculae join together in an interconnected network of trabeculae separated by spaces.

Question 12

Compact bone formation

Answer 12

Cells within the spaces of the spongy bone
specialize to form red bone marrow, and cells surrounding the developing bone specialize to form the periosteum. Osteoblasts from the periosteum lay down bone matrix to form an outer surface of compact
bone. The end products of intramembranous ossification are bones with outer compact bone surfaces and spongy centers. Remodeling converts woven bone to lamellar bone and contributes to the final shape of the bone

Question 13

ENDOCHONDRAL OSSIFIC ATION

Answer 13

• Forms bones of the base of the skull, part of the mandible, epiphyses of the clavicles, and most of remaining bones of skeletal system.
• Cartilage formation begins at end of fourth week of development.
• Some ossification beginning at about week eight; some does not begin until 18-20 years of age.

Question 14

bone growth

Answer 14

• Growth in length occurs at the epiphyseal plate, organized into five zones.
• Involves the formation of new cartilage by.
• Interstitial cartilage growth.
• Appositional growth on the surface of the cartilage

Question 15

Closure of epiphyseal plate

Answer 15

epiphyseal plate is ossified becoming the epiphyseal line. Between 12 and 25 years of age.

Question 16

Articular cartilage

Answer 16

does not ossify, and persists through life.

Question 17

what are the 5 main steps to endochondral ossification

Answer 17

cartilage model formation
bone collar formation
primary ossification formation
secondary ossification formation
adult bone