Cranium

Question 1

What are the two sections of the skull and what 8 bones make up the two portions?

Answer 1

• Calvarium and Floor
• Calvarium consists of: frontal, both parietals and occipital bones
• Floor consists of: both temporals, sphenoid and ethmoid bones

Question 2

What is the function of the cranium?

Answer 2

To surround and protect the brain

Question 3

What do the petrous ridges correspond with? What do they end with?

Answer 3

• TEA

- Internal acoustic meatus

Question 4

What are the routine projections of the skull? What are the optional ones?

Answer 4

• AP axial Towne, lateral, and PA 15 degree caldwell or 25-30 degree PA or 0 degree PA
• PA axial and SMV

Question 5

What anatomy is best demonstrated on the AP axial Towne method?

Answer 5

Dorsum sellae within the foramen magnum, petrous pyramids, occipital bone and posterior parietal bones

Question 6

What anatomy is best demonstrated on the PA 0 degree skull?

Answer 6

-temporal fossa,frontal and anterior ethmoid sinuses, cristi galli, and petrous pyramids fill the orbits

Question 7

What anatomy is best demonstrated on the lateral skull?

Answer 7

-Superimposed halves of cranium, sella turcica, A and P clinoid processes, and dorsum sellae.

Question 8

What anatomy is best demonstrated on the SMV projection?

Answer 8

• mandible, sphenoid and ethmoid sinuses, mastoid processes, foramen magnum and occipital bone.
• zygomatic arches, basal fx, or fluid within skull

Question 9

What is the thickest part of the skull? Thinnest? Widest?

Answer 9

• petrous portion=thickest
• squamous portion of temporal bone=thinnest
• between the parietal eminences=widest

Question 10

What does the sella turcica surround?

Answer 10

-pituitary gland or hypophysis

Question 11

What is the only cranial bone that articulates with ALL 7 other bones?

Answer 11

-Sphenoid

Question 12

What does the frontal bone articulate with?

Answer 12

both parietals, sphenoid, ethmoid and 8 facial bones

Question 13

What does the occipital bone articulate with?

Answer 13

both parietals, both temporals, sphenoid and atlas

Question 14

What does the temporal bones articulate with?

Answer 14

both parietals, occipital and sphenoid and 2 facial bones

Question 15

What does the ethmoid bone articulate with?

Answer 15

frontal bone and sphenoid, and 11 facial bones

Question 16

What is the location of the petrous ridges in the PA skull projection? PA axial?

Answer 16

PA=petrous pyramids filling the orbits

PA axial=petrous pyramids filling the lower 1/3 of the orbits

Question 17

Name and describe the three different skull shapes:

Answer 17

1. Mesocephalic=average
2. Brachycephalic=short and wide
3. Dolichocephalic=long and narrow

Question 18

What anatomy is best demonstrated on the PA axial Haas skull method?

Answer 18

occipital bone

Question 19

What anatomy is best demonstrated on a PA 15 degree caldwell method?

Answer 19

Petrous ridges are in lower 1/3 of orbits

Question 20

What may be visualized on a cross table lateral skull image following trauma?

Answer 20

Basilar skull fracture and inner cranial air fluid levels

Question 21

What can be done if the patient can’t tuck their chin enough to place the OML perp to the IR?

Answer 21

Place IOML perp to IR and increase CR angle to 37 degrees caudal. This maintains the 30 degree angle between the OML and the CR since theres a 7 degree difference between OML and IOML

Question 22

What are the 4 sinus groups and where are they located within the skull?

Answer 22

1. Maxillary-within each maxillary facial bone
2. Frontal-within the frontal bone
3. Ethmoid- within ethmoid bone
4. Sphenoid- within sphenoid bone

Question 23

When do each of the sinus groups develop?

Answer 23

Maxillary is present at birth
Frontal and Sphenoid-ages 6-7
Ethmoid- during puberty

Question 24

What position should the patient be in when demonstrating sinuses?

Answer 24

erect

Question 25

What is another name for the maxillary sinus?

Answer 25

Antrum of Highmore

Question 26

What pathology may be found in the sinuses?

Answer 26

Sinusitis

Question 27

What are the routine projections for the sinuses?

Answer 27

PA Caldwell
Parietoacanthial waters
Lateral

*Special- SMV and Parietoacanthial transoral

Question 28

What sinus group is best demonstrated on each projection?

Answer 28

PA Caldwell-frontal and ethmoid
Waters-maxillary
Lateral-all sinuses
SMV- sphenoid sinuses

Question 29

What projection can be obtained if the patient is unable to stand?

Answer 29

cross table lateral

Question 30

What is the function of the sinuses?

Answer 30

Serve as a resonating chamber for the voice
decrease weight of skull
To moisten warm and filter inhaled air
Act as shock absorber in trauma

Question 31

Why is a proper technique important in radiography of the sinuses?

Answer 31

Over penetration can diminish existing pathology

Under penetration can simulate pathology that doesn’t exist

Question 32

What do the sinuses communicate with?

Answer 32

with each other and the nasal cavity

Question 33

Where is the bregma located?

Answer 33

anterior end of the sagittal suture

Question 34

Where is the lambda located?

Answer 34

posterior end of the sagittal suture

Question 35

Where is the pterion located?

Answer 35

at the junction of parietal, temporal and greater wing of sphenoid

Question 36

Where is the asterion located?

Answer 36

a point posterior to the ear where the sqamosal and lambdoidal sutures meet.

Question 37

When do the sutures begin to fuse?

Answer 37

Lambda, sphenoid and mastoid close within a few month of birth.
Bregman doesn’t fuse until 18 months