1/19/16 Development of the Craniofacial Skeleton

Question 1

What is intramembranous bone ossification?

Answer 1

-Bone that is formed from a condensation of mesenchyme

Question 2

What type of bone is formed from endochondral ossification?

Answer 2

-Long bones

Question 3

What type of bones are formed from intramembranous bone ossification?

Answer 3

• Most of the mandible

- Skull plates

Question 4

What is the start of ossification, whether conversion of cartilage to bone, or condensation and ossification of mesenchyme/neural crest?

Answer 4

-Initiation

Question 5

What two cells contribute to the mesenchyme?

Answer 5

• mesoderm

- neural crest

Question 6

What is the addition of more bony matrix to a pre-existing bone; thickening, elongation?

Answer 6

-Growth

Question 7

What is displacement (primary) of bone?

Answer 7

-movement of a bone due to its own growth

Question 8

What is displacement (secondary) of bone?

Answer 8

-movement of a bone due to the growth of other bones

Question 9

What is remodeling of bone?

Answer 9

-Growth involving simultaneous deposition and resorption on all peri and endosteal surfaces.

Question 10

What happens to the bone in remodeling?

Answer 10

• change size
• shape
• proportion

Question 11

What is drift in bone?

Answer 11

-Remodeling that results in movement of a bone towards the deposition surface

Question 12

What is the functional matrix?

Answer 12

-A tissue that guides a bones growth by exerting a force upon the bone

Question 13

Where are two places that bone growth can occur?

Answer 13

• periosteal surfaces

- endosteal surfaces

Question 14

T/F

Bone resorption and bone deposition rates occur equally at all times in life.

Answer 14

False

Bone resorption and deposition rates can be different and change over time

Question 15

What are growth fields?

Answer 15

-Where matrix can be laid down or resorbed

Question 16

What are growth sites?

Answer 16

-Fields of significance to growth of a bone

Question 17

What are growth centers?

Answer 17

-Special growth sites, control overall growth of bone

Question 18

What are the two parts of the neurocranium?

Answer 18

• Calvaria

- Cranial base

Question 19

What is the calvaria?

Answer 19

• Desmocranium

- Skull cap

Question 20

What type of bone formation is the calvaria?

Answer 20

-Intramembranous bone

Question 21

What is the origin of the Calvaria?

Answer 21

• Paraxial mesoderm

- neural crest

Question 22

What type of bone formation is the cranial base?

Answer 22

-Endochondral bone

Question 23

What is the origin of the cranial base?

Answer 23

• primarily neural crest

- special sense organ capsular tissues

Question 24

What is the term for facial skeleton?

Answer 24

-viscerocranium

Question 25

What is the viscerocranium derived from?

Answer 25

-pharyngeal arches

Question 26

What part of the skull grows much more postnatally than the desmocranium?

Answer 26

-Viscerocranium

Question 27

What bones are part of the calvaria (desmocranium)?

Answer 27

- Frontal - Parietal - Parts of occipital - Temporal - Sphenoid

Question 28

What is the inner layer (endomeninx) membrane that encapsulates the developing brain formed from?

Answer 28

-neural crest that gives rise to the pia mater and arachnoid mater

Question 29

What is the outer layer (ectomeninx) membrane that encapsulates the developing brain formed from?

Answer 29

-neural crest and paraxial mesoderm that gives rise to the dura mater and the Calvaria bone

Question 30

What holds the bones of the clavaria together?

Answer 30

-Sutures

Question 31

What is an un-ossified suture between 2 or more skull bones called?

Answer 31

-Fontanelles

Question 32

What is anencephaly?

Answer 32

-Failure of rostral neural tube to close

Question 33

What is craniosynostosis?

Answer 33

-Premature fusion of the cranial vault sutures

Question 34

What bones are part of the cranial base (chondrocranium)?

Answer 34

- Frontal - Parietal - parts of occipital - temporal - sphenoid

Question 35

What in the floor of the brain forms cartilage in response to notochord and other epithelial signals?

Answer 35

-Ectomeninx

Question 36

T/F | The nasal capsule is also considered part of the cranial base (chondrocranium)

Answer 36

True

Question 37

AS the chondrocranium grows what happens to the maxilla?

Answer 37

-It pushes the maxilla and rest of the facial skeleton down and forward

Question 38

What forms from the maxillary prominence and is an intramembranous ossification of mesenchyme?

Answer 38

-Maxilla proper

Question 39

What forms from frontonasal process and forms the primary plate that fuses early with the maxilla proper that occurs from intramembranous ossification?

Answer 39

-Premaxilla

Question 40

What type of ossification does the mandible use to grow?

Answer 40

-Intramembranous ossification

Question 41

What does the bone in the mandible form lateral to?

Answer 41

-Meckel's carilage

Question 42

What part of the mandible form via endochondral ossification?

Answer 42

-Condyle on the articular ends via condylar cartilage

Question 43

T/F | Meckel's cartilage forms the mandible proper

Answer 43

False | -It disappears anteriorly and doesn't become the mandible proper

Question 44

What is condylar cartilage a derivative of?

Answer 44

-Meckels cartilage