Cranium Flashcards
What are the two sections of the skull and what 8 bones make up the two portions?
- Calvarium and Floor
- Calvarium consists of: frontal, both parietals and occipital bones
- Floor consists of: both temporals, sphenoid and ethmoid bones
What is the function of the cranium?
To surround and protect the brain
What do the petrous ridges correspond with? What do they end with?
- TEA
- Internal acoustic meatus
What are the routine projections of the skull? What are the optional ones?
- AP axial Towne, lateral, and PA 15 degree caldwell or 25-30 degree PA or 0 degree PA
- PA axial and SMV
What anatomy is best demonstrated on the AP axial Towne method?
Dorsum sellae within the foramen magnum, petrous pyramids, occipital bone and posterior parietal bones
What anatomy is best demonstrated on the PA 0 degree skull?
-temporal fossa,frontal and anterior ethmoid sinuses, cristi galli, and petrous pyramids fill the orbits
What anatomy is best demonstrated on the lateral skull?
-Superimposed halves of cranium, sella turcica, A and P clinoid processes, and dorsum sellae.
What anatomy is best demonstrated on the SMV projection?
- mandible, sphenoid and ethmoid sinuses, mastoid processes, foramen magnum and occipital bone.
- zygomatic arches, basal fx, or fluid within skull
What is the thickest part of the skull? Thinnest? Widest?
- petrous portion=thickest
- squamous portion of temporal bone=thinnest
- between the parietal eminences=widest
What does the sella turcica surround?
-pituitary gland or hypophysis
What is the only cranial bone that articulates with ALL 7 other bones?
-Sphenoid
What does the frontal bone articulate with?
both parietals, sphenoid, ethmoid and 8 facial bones
What does the occipital bone articulate with?
both parietals, both temporals, sphenoid and atlas
What does the temporal bones articulate with?
both parietals, occipital and sphenoid and 2 facial bones
What does the ethmoid bone articulate with?
frontal bone and sphenoid, and 11 facial bones
What is the location of the petrous ridges in the PA skull projection? PA axial?
PA=petrous pyramids filling the orbits
PA axial=petrous pyramids filling the lower 1/3 of the orbits
Name and describe the three different skull shapes:
- Mesocephalic=average
- Brachycephalic=short and wide
- Dolichocephalic=long and narrow
What anatomy is best demonstrated on the PA axial Haas skull method?
occipital bone
What anatomy is best demonstrated on a PA 15 degree caldwell method?
Petrous ridges are in lower 1/3 of orbits
What may be visualized on a cross table lateral skull image following trauma?
Basilar skull fracture and inner cranial air fluid levels
What can be done if the patient can’t tuck their chin enough to place the OML perp to the IR?
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
What are the 4 sinus groups and where are they located within the skull?
- Maxillary-within each maxillary facial bone
- Frontal-within the frontal bone
- Ethmoid- within ethmoid bone
- Sphenoid- within sphenoid bone
When do each of the sinus groups develop?
Maxillary is present at birth
Frontal and Sphenoid-ages 6-7
Ethmoid- during puberty
What position should the patient be in when demonstrating sinuses?
erect
What is another name for the maxillary sinus?
Antrum of Highmore
What pathology may be found in the sinuses?
Sinusitis
What are the routine projections for the sinuses?
PA Caldwell
Parietoacanthial waters
Lateral
*Special- SMV and Parietoacanthial transoral
What sinus group is best demonstrated on each projection?
PA Caldwell-frontal and ethmoid
Waters-maxillary
Lateral-all sinuses
SMV- sphenoid sinuses
What projection can be obtained if the patient is unable to stand?
cross table lateral
What is the function of the sinuses?
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
Why is a proper technique important in radiography of the sinuses?
Over penetration can diminish existing pathology
Under penetration can simulate pathology that doesn’t exist
What do the sinuses communicate with?
with each other and the nasal cavity
Where is the bregma located?
anterior end of the sagittal suture
Where is the lambda located?
posterior end of the sagittal suture
Where is the pterion located?
at the junction of parietal, temporal and greater wing of sphenoid
Where is the asterion located?
a point posterior to the ear where the sqamosal and lambdoidal sutures meet.
When do the sutures begin to fuse?
Lambda, sphenoid and mastoid close within a few month of birth.
Bregman doesn’t fuse until 18 months
