Outline 14: Skull and Facial Skeleton

Question 1

Allows baby to pass through birth canal and for skull growth

Answer 1

• At birth the brain is 25% of adult volume

- At 2 years the brain is 75% of adult volume

Question 2

Fontanelles

Answer 2

-Open spots in the skull

Question 3

Plagiocephaly

Answer 3

• External Molding
• The head being pressed consistently then they develop a flat spot
• Back of the head is the most common kind

Question 4

Cranial synostosis

Answer 4

• One or more of the fibrous sutures in an infant skull prematurely fuses by turning into bone, which changes the growth pattern of the skull
• Usually partial fusion
• Causes: bulging in head structure and pushes eyes out to make room for the growing brain
• Small window to open sutures so brain can grow properly

Question 5

Decision threshold – 6 mos

Answer 5

• Decisions about surgery need to be made before 6 months of age
• Too much brain growth will have occurred

Question 6

Skull- 8 Bones(2 pairs)

Answer 6

Frontal. Parietal, Occipital, Temporal, Ethmoid, Sphenoid bone

Question 7

1. Frontal bone

Answer 7

a. Forms forehead (squamous portion)
b. Anterior forms eye sockets (made up of 7 bones)
 Supraorbital margin
c. Single structure
d. Articulates with parietal, sphenoid bone, ethmoid bone

Question 8

Parietal bone; paired

Answer 8

a. Forms mid-portion of skull and skull cap (top of head)
b. Bulk of brain case
c. 2 bones
d. Largest portion

Question 9

Occipital bone

Answer 9

a. Forms back and part of the underside of the skull (posterior/inferior skull)
b. Provides articulation with the vertebral column
c. Articulates with Atlas
d. Brain case
e. Forms roof of pharynx
f. Forms most of the base of the skull

Question 10

Temporal bone; paired

Answer 10

a. Forms the side of the skull and houses sensory organs for hearing and balance (inner ear & middle ear)
b. Lateral portion of skull
c. Petrus portion (forms base of skull)

Question 11

5 parts of Temporal Bone:

Answer 11

1. Squamous
2. Zygomatic process
3. Mastoid process
   - Filled with air cells
   - Behind ear
4. Styloid process
5. Tympanic
   - Part of the ear canal

Question 12

Ethmoid bone

Answer 12

a. Forms a small portion of the anterior floor of the cranial cavity
b. Contributes to nasal septum with the perpendicular plate
c. Contributes to the middle and superior nasal cavity with the cribriform plate
d. Midline (central)
e. Complex bone
f. Flat plate in middle (mostly septum)
g. Crista Golli (cocks comb): sharp point
h. Cribiform plate: horizontal/ forms base of skull
i. Superior nasal conchea
j. Middle nasal conchea
k. Largest part of nasal septum
l. Lots of Olfactory nerve fibers (CN I)

Question 13

Sphenoid bone

Answer 13

a. Forms the bulk of the floor of the mid-portion of the cranial cavity
b. Most complicated bone in the body
c. Butterfly shaped
d. Articulates with all the bone in the skull
e. Unpaired central structure
f. Roof of nasal pharynx
g. Part of eye sockets
h. Part of the base of the brain
i. Goes straight through the skull
j. Contains many holes (passageways)

Question 14

Sinuses – 4 paranasal sinuses

Answer 14

Frontal, Maxillary, Ethmoid, Sphenoid

Question 15

Frontal Sinus

Answer 15

• Paired
• Most superior
• Deep to eyebrows
• Located in frontal bone (eyebrow area)
• Opens up to anterior part of the nasal cavity

Question 16

Maxillary Sinus

Answer 16

• Largest of the sinuses
• Forms the lateral walls of the nasal cavity (base); extends sideways
• Paired
• Roof = orbit of the eye

Question 17

Skull and Facial Skeleton: framework for:

Answer 17

articulation and resonance

Question 18

Ethmoid Sinus

Answer 18

• More complex
• Series of open chambers
• Between nasal cavity and orbits of the eyes
• Superior to conchae
• Has a superior, middle and inferior
• Lots of them

Question 19

Sphenoid Sinus

Answer 19

• Paired

* Just above pharynx (little cubes)

Question 20

Function of sinuses

Answer 20

•	Important for growth pattern (skull & facial)
-gives room for bones to expand 
•	Decreases weight of the skull
•	Cavities within bones filled with air (hallow)
•	Named for the bones they are in
•	Nasal resonance (maybe?)
•	Lined by ciliated mucus membrane 
-Tiny hair line structures (cilia)
	*gets out dirt particles
	*also lines airways
•	Can get infected