Ch. 11 Skull Workbook Flashcards
total number of cranium bones
8
total number of facial bones
14
what are the 4 cranial bones that form the calvaria (skullcap)
- frontal
- right parietal
- left parietal
- occipital
what are the 4 cranial bones that form the floor of the cranium
- right temporal
- left temporal
- sphenoid
- ethmoid
the small horizontal plate of the ethmoid
cribriform plate
the vertical plate of the ethmoid bone forming the upper portion of the bony nasal septum
perpendicular plate
a structure found in the middle of the sphenoid bone that surrounds the pituitary gland
sella turcica
what is the posterior aspect of the sella turcica called
dorsum sellae
which structure of the sphenoid bone allows for the passage of the optic nerve and is the actual opening into the orbit
optic foramen
which structures of the sphenoid bone help to form part of the lateral walls of the nasal cavities
medial and lateral pterygoid processes
which radiographic projection best demonstrates the sella turcica and dorsum sellae
lateral projection
which aspect of the frontal bone forms the superior aspect of the orbit
orbital or horizontal portion
cranial sutures are classified as what type of joints
fibrous - synarthrodial
small, irregular bones that sometimes develop in adult skull sutures
sutural or wormian bones
where are sutural/wormian bones most often found
lambdoidal suture
what term describes the superior rim of the orbit
supraorbital margin (SOM)
what is the name of the notch that separates the orbital plates from each other
ethmoidal notch
which cranial bones form the upper lateral walls of the calvarium
right and left parietals
which cranial bone contains the foramen magnum
occipital bone
a small prominence located on the squamous portion of the occipital bone
external occipital protuberance, or inion
what is the name of the oval processes found on the occipital bone that help form the atlanto-occipital joint
occipital condyles or lateral condylar portions
what are the 3 aspects of the temporal bones
- squamous
- mastoid
- petrous
which is the densest aspect of the temporal bone
petrous portion
which external landmark corresponds with the level of the petrous ridge
top of the ear attachment (TEA)
which opening in the temporal bone serves as a passageway for nerves of hearing and equilibrium
internal acoustic meatus
what are the 3 aspects of the temporal bone
- squamous
- mastoid
- petrous
which aspect of the temporal bone is considered the densest
petrous portion
which structure makes up the cartilaginous external ear
auricle or pinna
how long is the average external acoustic meatus (EAM)
1” (2.5 cm)
which small membrane marks the beginning of the middle ear
tympanic membrane (eardrum)
what is the collective term for the small bones of the middle ear
auditory ossicles
which structure allows for communication between the nasopharynx and middle ear
eustachian or auditory tube
what is the major function of the eustachian/auditory tube
equalize the atmospheric pressure within the middle ear
which structure serves as an opening between the mastoid portion of the temporal bone and the middle ear
aditus
what is the name of the thin plate of bone that separates the mastoid air cells from the brain
tegmen tympani
which of the auditory ossicles picks up sound vibrations from the tympanic membrane
malleus (hammer)
which of the auditory ossicles is considered the smallest
stapes (stirrup)
which of the auditory ossicles resembles a premolar tooth
incus (anvil)
what is the name of the small membrane that connects the middle to the inner ear
oval or vestibular window
which two sensory functions occur within the inner ear
- hearing
- equilibrium
what is the name of the small membrane found at the base of the cochlea
round or cochlear window
T/F - the semicircular canals include a closed system specific to the sense of hearing
false
bacterial infection of the mastoid process
mastoiditis
growth arising from a mucous membrane
polyp
hereditary disease involving excessive bone formation of middle ear
otosclerosis
benign, cystic mass or tumor of the middle ear
cholesteatoma
new and abnormal growth
neoplasia
benign tumor of the auditory nerve sheath
acoustic neuroma
radiographic appearance of acoustic neuroma
expansion of the internal acoustic canal
what imaging modality best demonstrates otosclerosis
CT
skull width <75% of length
dolichocephalic
skull width between 75% and 80% of length
mesocephalic
skull width > or equal to 80% of length
brachycephalic
what is the angle between the midsagittal plane and the long axis of the petrous bone in a mesocephalic skull
47 degrees
the dolichocephalic skull has an angle between the midsagittal plane and long axis of the petrous bone of how much
40 degrees (<47 degrees)
T/F - two older terms for the orbitomeatal line (OML) are Reid’s base line and the anthropologic base line
false - infraorbitomeatal line (IOML)
what is the degree difference between the orbitomeatal line (OML) and the infraorbitomeatal line (IOML)
7-8 degrees
what is the degree difference between the orbitomeatal line (OML) and the glabellomeatal line (GML)
7-8 degrees
lateral junction of the eyelid
outer canthus
posterior angle of the jaw
gonion
a line between infraorbital margins and the EAM
infraorbitomeatal line (IOML)
corresponds to the highest “nuchal” line of the occipital bone
inion
a line between the glabella and alveolar process of the maxilla
glabelloalveolar line (GAL)
a line between the mental point and the EAM
mentomeatal line (MML)
located at the junction of the two nasal bones and the frontal bone
nasion
the small cartilaginous flap covering the ear opening
tragus
corresponds to the highest level of the facial bone mass
supraorbital groove (SOG)
a line between the midlateral orbital margin and the EAM
OML
the center point of the EAM
auricular point
a positioning line that is primarily used for the modified waters projection
lips-meatal line
a line used in positioning to ensure that the skull is in a true lateral position
interpupillary line
corresponds to the level of the petrous ridge
top of the ear attachment (TEA)
a smooth, slightly depressed area between the eyebrows
glabella
what is the average kVp range for skull radiography
75-90 kVp
what are the 5 most common errors made during skull radiography
- rotation
- tilt
- excessive neck flexion
- excessive neck extension
- incorrect CR angulation
of the 5 most common errors during skull radiography, which 2 are most common
rotation and tilt
bilateral horizontal fractures of the maxillae describes what type of fracture
Le Fort
which imaging modality is the most common neuroimaging procedure performed for the cranium
CT
which imaging modality is commonly performed on neonates with a possible intracranial hemorrhage
ultrasound
which imaging modality is most commonly performed to evaluate patients for Alzheimer disease
nuclear medicine
fracture that may produce an air-fluid level in the sphenoid sinus
basal skull fracture
destructive lesion with irregular margins
osteolytic neoplasm
also called a “ping-pong” fracture
depressed skull fracture
proliferative bony lesion of increased density
osteoblastic neoplasm
a tumor that may produce erosion of the sella turcica
pituitary adenoma
also known as osteitis deformans
paget disease
a bone tumor that originates in the bone marrow
multiple myeloma
what clinical indication may require an increase in manual exposure factors
advanced paget disease
which cranial bone is best demonstrated with an AP axial (Towne method) projection of the skull
occipital
when using a 30 degree caudad angle for the AP axial (Towne method) projection of the skull, which positioning line should be perp to the IR
OML
a properly positioned AP axial (Towne method) projection should place the dorsum sellae into the middle aspect of what
foramen magnum
a lack of symmetry of the petrous ridges indicates what problem with a radiograph of an AP axial projection
rotation
if a patient can’t flex the head adequately for the AP axial (Towne method), what could the tech do instead
place IOML perp to IR and angle 37 degrees caudad
what evidence on an AP axial (Towne method) radiograph indicated whether the correct CR angle and correct head flexion were used
dorsum sellae and posterior clinoids should be projected into the foramen magnum
what CR angle should be used for the PA axial (Haas method) projection for the cranium
25 degree cephalad
where is CR centered for a lateral projection of the skull
2” (5 cm) above the EAM
which specific positioning error is present if the mandibular rami are not superimposed on a lateral skull radiograph
rotation
where will the petrous ridges be projected with a 15 degree PA axial (caldwell) projection of the cranium
in the lower 1/3 of the orbits
which specific positioning error is present if the petrous ridges are projected higher in the orbits than expected for a 15 degree PA axial projection
excessive flexion or insufficient CR angle
which projection of the cranium produces an image of the frontal bone with little or no distortion
0 degree PA
for a patient with possible trauma, what must be determined before performing the submentovertical (SMV) projection of the skull
rule out any possible cervical fractures or subluxation
what positioning error has been committed if the EAMs are not superimposed with one of them more superior than the other on a lateral projection of the cranium
tilt of the skull
which skull positioning line is placed parallel to the plane of the IR for the SMV projection
IOML
which of the following projections best demonstrates the sella turcica in profile
lateral
which of the following projections best demonstrates the foramen rotundum
25-30 degree PA axial
which of the following projections best demonstrates the clivus in profile
lateral
where does the CR exit for a PA axial (Haas method) projection of the skull
1.5” (4 cm) superior to the nasion
which imaging modality is best to differentiate between an epidural and a subdural hemorrhage
CT
a radiograph of an AP axial (Towne method) projection of the cranium shows the right petrous ridge is wider than the left. what positioning error is present
rotation of skull; rotation of patient’s face toward the left
a radiograph of a 15 degree PA axial (caldwell) projection of the cranium demonstrates the petrous ridges are projected at the inferior orbital margin. what positioning error led to this
excessive extension or excessive caudad CR angle
a radiograph of a 15 degree PA axial (caldwell) projection demonstrates the distance between the right midlateral orbital borders and lateral margin of the skull cortex is greater than the left side. what positioning error led to this
rotation of the patient’s face (skull) to the left
a radiograph of an SMV projection of the skull shows the mandibular condyles are within the petrous bone , what positioning error led to this
insufficient extension of the skull, or CR was not perp to IOML
a radiograph of a lateral projection of the skull shows the orbital plates are not superimposed (one orbital plate is slightly superior to the other) what positioning error led to this
skull tilt
a lateral skull radiograph demonstrates one mandibular ramus about 0.5 cm more anterior than the other, what positioning error occurred
skull rotation
an AP axial (Towne method) radiograph for the cranium demonstrates the dorsum sellae projected above or superior to the foramen magnum, the foramen magnum is distorted, what positioning error occurred
CR angled <37 degrees to the IOML, or <30 degree to the OML (would be caused by 30 degree angle to IOML) error can be addressed with more flexion of neck
a patient comes to the radiology department with a possible tumor of the pituitary gland, which radiographic projection of the cranium best demonstrates any bony involvement of the sella turcica
collimated, lateral projection of sella turcica
a patient with a possible linear fracture of the right parietal bone enters the ER, what single radiographic projection of the skull best demonstrates this fracture
right lateral projection of skull
a patient comes to the radiology department for a skull series, but the patient cannot assume the correct position for either version of the AP axial (Towne method) projection because of a very short neck and severe spinal kyphosis, what can the tech do to demonstrate the occipital bone
perform the PA axial projection (Haas method)
a patient with a possible basal skull fracture enters the ER, no CT scanner is available, what position may provide radiographic evidence of this fracture
horizontal beam (dorsal decub) lateral position - will demonstrate possible air-fluid level in the sphenoid sinus
a neonate has a clinical history of craniosynostosis, due to the age of the patient, the physician does not order a radiographic procedure of the cranium, what other imaging modality can be performed to evaluate the patient for this condition
ultrasound
a patient with a clinical history of acoustic neuroma comes to the radiology department. what imaging modality or modalities can be performed for this type of pathology
MRI or CT
a radiograph of an AP axial (Towne method) projection for the cranium shows that the posterior arch of C1 is projected within the foramen magnum, the dorsum sellae is superimposed on the posterior arch as well, what is/are the errors
over angulation of CR or excessive flexion of neck
a radiograph of an AP axial (Towne method) projection for the cranium shows the mid-to lower mandible is cut off and not demonstrated, what should the tech do
no repeat required - due to elongation of the facial mass with this projection, cutting off aspects of the mandible is acceptable
