Development & Organization of the Skull

Question 1

What is the calvarium?

Answer 1

The components of the neurocranium that provide a protective cover around the brain and special sense organs, formed via intramembranous ossification

Question 2

How are the bones of the calvarium formed?

Answer 2

Intramembranous ossification

Question 3

What are the bones of the calvarium?

Answer 3

Parietal, frontal, squamous portion of occipital, squamous portion of temporal

Question 4

What is the basicranium?

Answer 4

Bones of the neurocranium that form the supportive floor/cranial base. Acts as an interface between upper neurocranium and facial skeleton. Bones formed endochondrally from cartilaginous precursors.

Question 5

How are the bones of the basicranium formed?

Answer 5

Endochondrally from cartilaginous precursors

Question 6

What are the bones of the basicranium?

Answer 6

Ethmoid, sphenoid (primary components), temporal (petrous and mastoid parts), occipital (condyles and basilar portion)

Question 7

What is the viscerocranium?

Answer 7

Facial skeleton derived from the branchial arches flanking the foregut

Question 8

What are the bones of the viscerocranium?

Answer 8

Maxilla, zygomatic, nasal, lacrimal, palatine, vomer, mandible

Question 9

What is the cranial cavity?

Answer 9

A bony cavity that contains brain and associated soft tissues

Question 10

What is an orbital cavity?

Answer 10

A bony cavity that contains eyeballs and associated soft tissues

Question 11

What is a temporal bone cavity/canals?

Answer 11

A bony cavity that contains soft tissues associated with hearing and balance

Question 12

What is a nasal cavity?

Answer 12

A bony cavity that contains structures associated with olfaction, respiration, and thermoregulation

Question 13

What is an oral cavity?

Answer 13

A bony cavity that contains soft tissue associated with taste, suckling, chewing, swallowing, speech, and respiration

Question 14

What are fibrous joints?

Answer 14

Connective tissue sutures that connect bones of the skull, which allows for growth to occur and the brain to expand

Question 15

What are gomphosis joints?

Answer 15

Fibrous peridontal ligaments that anchor tooth roots into the alveolar process of the bony maxilla or mandible

Question 16

What are synchondroses?

Answer 16

Cartilaginous growth plates (ex. basioccipital synchondrosis) that fuse at some point (some fuse before birth, others in early adulthood)

Question 17

What is a symphysis?

Answer 17

An area of connective tissue that connects two halves of the mandible that fully ossifies and fuses at around 2 yrs of age

Question 18

Where does endochondral ossification typically occur?

Answer 18

Occurs in hyaline cartilage prototype models of future bones (ex. postcranial bones, skull base)

Question 19

Where does intramembranous ossification usually occur?

Answer 19

Occurs in dense sheets of membranous connective tissue that transforms into bone (ex. large portions of skull, most of clavicle)

Question 20

Which bones of the calvarium form intramembranously?

Answer 20

Frontal, parietals, squamous occipital, squamous temporal

Question 21

How are viscerocranium bones predominantly formed?

Answer 21

Intramembranous ossification

Question 22

What is the ossification pathway:

Frontal bone

Answer 22

Intramembranous ossification

Question 23

What is the ossification pathway:

Parietal bone

Answer 23

Intramembranous ossification

Question 24

What is the ossification pathway:

Temporal bone

Answer 24

Endochondral with intramembranous parts

Question 25

What is the ossification pathway:

Occipital bone

Answer 25

Endochondral with intramembranous parts

Question 26

What is the ossification pathway:

Sphenoid bone

Answer 26

Endochondral with intramembranous parts

Question 27

What is the ossification pathway:

Ethmoid bone

Answer 27

Endochondral ossification

Question 28

Which facial bones form endochondrally?

Answer 28

Inferior concha, hyoid

Question 29

Which bones of the skull are derived from the head ectomesenchyme?

Answer 29

Frontal bones, anterior portion of chondrocranium (ethmoid, anterior part of sphenoid), and viscerocranial bones

Question 30

How is the head ectomesenchyme derived?

Answer 30

From cells of the neural crest

Question 31

What is craniosynostosis?

Answer 31

Premature closure/fusion of cranial structures that lead to skull bone deformities

Question 32

What are fontanelles?

Answer 32

Gaps between skull bones that have yet to ossify

Question 33

What are the three primary patterns of bone growth in the skull?

Answer 33

1) cellular proliferation at cartilaginous growth plates
2) sutural growth (osteoblastic activity within sutures)
3) remomdeling through resorption/deposition