Chapter 11: Cranium

what are the 2 sections of the cranium?

1. skull cap or calvarium

2. floor of cranium

how many cranium bones are there?

8

how many facial bones are there?

14

what are the 4 bones of the skull cap or calvarium?

1. frontal

2. occipital

3. right parietal bone

4. left parietal bone

what are the 4 bones of the floor of cranium?

1. ethmoid

2. sphenoid

3. right temporal

4. left temporal

what are the 2 sections of the frontal bones?

1. squamous (vertical anatomy)

2. orbital (horizontal anatomy)

what are these examples of:

• orbit (superior)

• glabella

• frontal tuberosity/eminence

squamous bones

what is this an example of:

• roof of orbits

orbital/horizontal bones

upper/most superior portion of orbits

orbital plate

ethmoid bone is in the ___ ___

ethmoid notch

nasal bones join with frontal bones here

nasal spine

make up upper and lateral walls of cranium, square shape

parietal bones

1 point to the other, widest point of skull

parietal eminence (2)

most posterior aspect of skull

occipital bone

where C1 attaches to skull, forms atlanto-occipital joint

occipital condyles

spinal cord passes through the ___ ___

foramen magnum

external occipital protuberance is also called

inion

opening under zygomatic process

temporomandibular fossa

plays a role in hearing, ventilates the ears

mastoid air cells

parietal, sphenoid, temporal join here

pterion

weakest portion of skull

pterion (located on temple)

forms sides of skull, part of cranial floor and structures that surround ear

temporal bone

joins with temporal process of zygoma to create zygomatic arch (cheek bone)

zygomatic process of temporal bone

mastoid portion contains ___ ___(tip)

mastoid process

opens to organs of hearing

EAM

top of ear attachment

TEA

part of temporal bone that is thin, vertical, and weakest part of skull

squamous portion

part of temporal bone where mastoid air cells are located

mastoid portion

part of temporal bone that houses organs of hearing + balance, thickest and most dense part of skull, shows up nicely radiographically

petrous portion (2)

(petrous pyramid)

(pars petrosa)

(petromastoid portion)

larger wing of sphenoid

greater wing

smaller wing of sphenoid

lesser wing

“reins” of sphenoid

anterior clinoid process

“back of saddle” of sphenoid

posterior clinoid process

bat or butterfly like appearance, located centrally at base of skull, part of cranial floor, forms a portion of orbits and parts of nasal cavity

sphenoid bone

anterior to temporal bones

sphenoid bone

contains sphenoid sinus

body of sphenoid

“saddle of bat,” pituitary gland located here (master gland)

sella turnica

opening between greater and lesser wings

superior orbital fissure

what does the medial pterygoid process contain?

pterygoid hamulus (hook)

optic nerve runs through ___ ___

optic foramen

what are the names of the 3 other openings where nerves and vessels pass through on the greater wing of the sphenoid

1. foramen ovale

2. foramen rotundum

3. foramen spinosum

posterior portion of “saddle” (sella turcica)

dorsum sellae

from the frontal view you can only see a small portion of the ___

sphenoid

upward pointing ridge on ethmoid bone

crista galli

on the sides of crista galli, allows nerves to pass through to brain

cribriform plate

divides nasal cavity, forms portion of nasal septum

perpendicular plate

spongy bone, sits between orbits, anterior to sphenoid, helps form nasal cavity and anterior cranial floor, contains structures that help with smell, sinus drainage & air flow through nasal cavity

ethmoid bone

contains ethmoid sinus, big portion on slides of plates

lateral labyrinth (masses)

forms inside of nasal cavity

superior and middle nasal concha

___ nasal concha warms and humidifies inhaled air

middle nasal concha (turbinate)

fibrous joints connecting skull bones

cranial sutures

what are the 4 cranial sutures?

1. coronal

2. lambdoidal

3. squamosal

4. sagittal

which suture?

• between frontal and parietal bones

coronal

which suture?

• posterior, between occipital and parietal bones

lambdoidal

which suture?

• lateral, between parietal and temporal

squamosal

which suture?

• between 2 parietals

sagittal

where sutures cross

junction points

what are the 4 junction points?

1. asterion (2)

2. bregma (1)

3. lambda (1)

4. pterion (2)

which junction point?

• squamosal and lambdoidal cross

asterion

which junction point?

• coronal and sagittal cross

bregma

which junction point?

• lambdoidal and sagittal cross

lambda

which junction point?

• coronal and squamosal cross

pterion

sutures are wider and more flexible (membrane covered) in ___

infants

gaps between sutures (soft spots)

fontanels

what are the names of the 6 fontanels? (3 names)

1. anterior and posterior

2. R and L sphenoid

3. R and L mastoid

size and shape of skull

morphology

average size skull

mesocephalic skull

shorter and wider skull

brachycephalic skull

long and narrow skull

dolichocephalic skull

we need a minimum of ___ skull positioning lines

2

we need a minimum of ___ skull positioning lines in the lateral position

3

*know the skull positioning lines*

this position is preferred because of air-fluid levels, comfort, and easier for hypertension patients

erect

this position is preferred for trauma patients

recumbent

for ___ we always use manual technique

sinus

positioning error:

look at mid-sagittal plane on axis (“no”) & vertical structures like mandible

rotation

positioning error:

look at mid-sagittal plane angle (one ear close to other) & horizontal structures like orbital plates

tilt

positioning error:

chin too tucked

excessive neck flexion

positioning error:

chin extended

excessive neck extension

what are the 5 positioning errors?

1. rotation

2. tilt

3. excessive neck flexion

4. excessive neck extension

5. incorrect CR angle

what are the 2 special projections for cranium?

1. PA axial (Haas)

2. SMV (submentovertex)

cranium routine?

1. AP axial (towne)

2. R or L lateral

3. PA 15º (caldwell) or PA 0º

do we use 30º caudad for OML or IOML?

OML

do we use 37º caudad for OML or IOML?

IOML

• CR is 2 ½ inches above glabella

• MSP perpendicular

• OML or IOML perpendicular

AP axial (towne)

evaluation criteria:

• dorsum sellae projected within foramen magnum

• petrous ridges symmetric (shorter = way patient is looking, lower = way pt is tilted)

AP axial (towne)

• CR 2 inches superior to EAM

• MSP parallel

• IOML parallel

• IP perpendicular

right or left lateral

CR 0º exits at ___ (PA cranium)

glabella

CR 15º caudad exits at ___ (PA cranium)

nasion

• CR at gabella or nasion

• OML perpendicular

• MSP perpendicular

PA cranium

evaluation criteria:

petrous pyramids over lower 1/3 of orbits

PA 15º (caldwell)

evaluation criteria:

petrous pyramids superimpose/over superior orbital regions (margins)

PA 0º

• MSP perpendicular

• IOML parallel

SMV (submentovertical)

evaluation criteria:

mandibular condyles anterior to petrous pyramids

SMV (submentovertical)

• reverse of towne

• OML perpendicular

• MSP perpendicular

• evaluation criteria: skull is elongated

PA axial (Haas)