Chapter 11 - Cranium Self Test

To prevent tilting of the skull for the lateral projection of the cranium, the __________________________ line is placed perpendicular to the image receptor.

IPL

Where is the central ray centered for a lateral projection of the cranium?

2 inches superior to the EAM

What CR angulation is used for the AP axial projection of the TMJ with the OML perpendicular to the image receptor?

35 degree caudad

How much CR angle is required for the AP axial projection of the zygomatic arches if the IOML is placed perpendicular to the IR? (Hint: This is the same as for an AP axial skull.)

37 degrees

True/False: A Le Fort fracture produces a "free-floating" zygomatic bone.

False

True/False: All of the paranasal sinuses are contained within cranial bones, except the maxillary sinuses.

False

True/False: In general, all of the paranasal sinuses are fully developed by the age of 6 or 7 years.

False

True/False: Ultrasound of the sphenoid sinus can be performed to rule out sinusitis.

False

True/False: The modified Law method requires a tube angulation of 25 degrees caudad.

False, it is 15 degree caudad

Which plane is placed parallel to the IR with a true lateral projection of the facial bones?

GAL or midsagittal plane

Where are the petrous ridges projected for a properly positioned modified parietoacanthial projection?

lower half of the maxillary sinuses

Where is the CR centered for a lateral projection of the paranasal sinuses?

midway between outer canthus and EAM

Which aspect of the temporal bone contains the organs of hearing and balance?

petrous portion

What are the two terms for the small, irregular bones found in the adult skull sutures?

sutural or wormian bones

The sphenoid sinus lies directly inferior to the __________________________.

sella turcica

On average, how many separate cavities make up the frontal sinus?

2

Where is the central ray centered for an SMV projection of the skull?

1 1/2 inches inferior to the mentum

Match each of the following structures to its related cranial bone. ______ 1. Pterygoid hamulus ______ 2. Anterior clinoid processes ______ 3. Glabella ______ 4. Foramen ovale ______ 5. Perpendicular plate ______ 6. Superior nasal conchae ______ 7. Foramen magnum ______ 8. Cribriform plate ______ 9. Zygomatic process ______ 10. Lateral condylar portions ______ 11. Superciliary arch ______ 12. EAM ______ 13. Inion ______ 14. Sella turcica ______ 15. Petrous ridge A. Occipital B. Frontal C. Sphenoid D. Ethmoid E. Temporal F. Parietal

1. C 2. C 3. B 4. C 5. D 6. D 7. A 8. D 9. E 10. A 11. B 12. E 13. A 14. C 15. E

How much skull tilt and rotation are required for the oblique inferosuperior (tangential) projection for zygomatic arches?

15 inches toward IR

What type of CR angulation should be used for a PA axial projection of the mandible? A. None B. 10 to 15 degrees cephalad C. 20 to 25 degrees cephalad D. 5 degrees cephalad

C. 20 to 25 degrees cephalad

During an orthopantomographic procedure, it is important to keep the __________________________ positioning line parallel to the floor. A. OML B. AML C. IOML D. GAL

C. IOML

The CR is centered to exit at the level of the __________________________ for a well-positioned parietoacanthial projection. A. Nasion B. Glabella C. Inner canthus D. Acanthion

D. Acanthion

Which of the following is not an aspect of the maxilla? A. Frontal process B. Body C. Zygomatic process D. Ramus

D. Ramus

Which structures are found at the widest aspect of the skull?

Parietal Tubercles (eminences)

Which four cranial bones articulate with the frontal bone? A. ___________ B. ___________ C. ___________ D. ___________

Right Parietal Left Parietal Sphenoid Ethmoid

Situation: A radiograph of an SMV projection of the cranium demonstrates that mandibular condyles are projected into the petrous portion (pyramids) of the temporal bone. How must the position be altered during the repeat exposure to correct this error?

extend the skull further to place the IOML parallel to the IR

Situation: A radiograph of a 15-degree caudad PA axial projection of the cranium shows that the petrous ridges are at the level of the supraorbital margin. Without changing the central ray angle, how must the head position be modified during the repeat exposure to produce a more acceptable image?

increase extension of the skull to place the OML perpendicular to the IR (will project ridges into lower 1/3 of orbits)

What is the formal term for the left sphenoid fontanel in the adult?

left pterion

Which routine projection is best for demonstrating the maxillary sinuses?

parietoacanthial Water's method

Where is the CR centered for an SMV projection of the mandible?

1 1/2 inches inferior to mandibular symphysis

Where is the CR centered for a lateral projection of the nasal bones?

1/2 inch inferior to the nasion

A. What is the angle between the OML and plane of image receptor with a parietoacanthial (Waters method) projection? B. This places the __________________________ positioning perpendicular to the IR.

A. 37 degrees B. MML

A. How much central ray angle is required for the AP axial projection (Towne method) for a skull with the IOML perpendicular to the image receptor? B. What is the central ray angle for this same projection with a perpendicular OML?

A. 37 degrees caudad B. 30 degrees caudad

Match each of the following definitions or characteristics to the correct facial bone. (Use each choice only once.) ______ A. Mandible ______ B. Lacrimal bones ______ C. Palatine bones ______ D. Inferior nasal conchae ______ E. Nasal bones ______ F. Maxilla ______ G. Zygomatic bone 1. Contains four processes 2. Forms lower, outer aspect of orbit 3. Lie just anterior and medial to the frontal process of maxilla 4. Unpaired bone in the adult 5. Located anteriorly in medial aspect of orbit 6. Help to mix air drawn into nasal cavity 7. Possesses a vertical and horizontal portion

A. 4 B. 5 C. 7 D. 6 E. 3 F. 1 G. 2

______ A. Bone tumor originating in the bone marrow ______ B. Fracture evident by sphenoid sinus effusion ______ C. Condition that begins with bony destruction followed by bony repair ______ D. Destructive lesion with irregular margins ______ E. Fracture of the skull with jagged or irregular lucent line that lies at an angle to the axis of the bone ______ F. Tangential view may help in determining extent or degree of this fracture 1. Linear fracture 2. Paget's disease 3. Depressed fracture 4. Osteolytic neoplasm 5. Multiple myeloma right 6. Basal fracture

A. 5 B. 6 C. 2 D. 4 E. 1 F. 3

List the number of individual bones that articulate with the following cranial bones. A. Parietal bone: __________________________ B. Occipital bone: __________________________ C. Temporal bone: __________________________ D. Sphenoid: __________________________ E. Ethmoid: __________________________

A. 5 B. 6 C. 3 D. 7 E. 2

Identify the seven (cranial and facial) bones that form the bony orbit (Fig. 11.32). A. ___________ B. ___________ C. ___________ D. ___________ E. ___________ F. ___________ G. ___________

A. Lacrimal B. Ethmoid C. Frontal D. Sphenoid E. Palatine F. Zygoma G. Maxilla

1. The majority of the hard palate is formed by: A. Maxilla B. Palatine bones C. Zygomatic bone D. Mandible

A. Maxilla

Which of the classifications in the preceding question is considered an average-shaped skull? A. Mesocephalic B. Dolichocephalic C. Brachycephalic

A. Mesocephalic

The CR is centered to exit at the level of the __________________________ for a well-positioned 15-degree PA axial projection of the facial bones. A. Nasion B. Glabella C. Midorbits D. Acanthion

A. Nasion

Which of the following terms is defined as the large cartilaginous aspect of the external ear? A. Pinna B. Tragus C. Glabella D. Acanthion

A. Pinna

Which of the following positioning errors frequently results in a repeat exposure of a cranial position? A. Rotation B. Incorrect central ray placement C. Flexion D. Extension

A. Rotation

How much difference in degrees is there between the OML and the IOML? A. 10 degrees B. 7 to 8 degrees C. 3 degrees D. None (They represent the same positioning line.)

B. 7 to 8 degrees

Reid's base line is an older term for: A. GML B. IOML C. OML D. GAL

B. IOML

Which of the following imaging modalities provides an excellent distinction between normal and abnormal brain tissue? A. CT B. MRI C. Ultrasound D. Nuclear medicine

B. MRI

Which of the following landmarks corresponds to the highest level of the petrous ridge? A. EAM B. TEA C. Outer canthus D. Acanthion

B. TEA

How much skull rotation (from the lateral position) toward the image receptor is required for the axiolateral oblique projection specifically for the mentum? A. 10 to 15 degrees B. 30 degrees C. 45 degrees D. None. Keep the skull in the true lateral position.

C. 45 degrees

Which of the following skull classifications applies to a skull with an angle of 54 degrees between the midsagittal plane and the long axis of the pars petrosa? A. Mesocephalic B. Dolichocephalic C. Brachycephalic D. None of these

C. Brachycephalic

Which of the following factors prevents superimposition of the ramus on the cervical spine for the axiolateral oblique mandible projection? A. Angle CR 10 to 15 degrees cephalad B. Have patient open mouth during exposure C. Extend chin D. Rotate head toward IR

C. Extend chin

Which of the following bones is not part of the floor of the cranium? A. Temporal B. Ethmoid C. Occipital D. Sphenoid

C. Occipital

Which aspect of the frontal bone is thin-walled and forms the forehead? A. Orbital B. Horizontal C. Squamous D. Superciliary margin

C. Squamous

Situation: A patient with a clinical history of secondary osteomyelitis comes to the radiology department. Which imaging modalities or procedures can be performed to demonstrate the extent of damage to the sinuses?

CT, lateral, Caldwell, Waters, and SMV

Which of the following clinical indications may require a decrease in manual exposure factors? A. Pituitary adenoma B. Linear skull fracture C. Paget's disease D. Multiple myeloma

D. Multiple myeloma

Situation: A patient with a possible basilar skull fracture enters the emergency room. The physician wants a projection to demonstrate a possible sphenoid sinus effusion. Which projection of the cranium is best for this situation?

Horizontal beam (dorsal decubitus) lateral skull projection

Which positioning line is parallel to the IR for the SMV projection of the skull?

IMOL

Which positioning line, if placed parallel to the image receptor, ensures adequate extension of the head for the submentovertical projection for zygomatic arches?

IOML

Which positioning line is placed perpendicular to the image receptor for a modified parietoacanthial projection?

LML

Situation: A patient with possible facial fractures, including a possible "blowout" fracture to the right orbit, was brought from the emergency room to the radiology department. What special facial bone projection should be included with the basic facial bone routine of a lateral, parietoacanthial (Waters), and PA axial (Caldwell)?

Modified Waters method

Why should a horizontal CR be used for the erect PA (Caldwell) projection for sinuses rather than the usual 15-degree caudad angle?

To assess air fluid levels accurately

Situation: A patient with severe facial bone injuries comes into the emergency room. The patient is wearing a cervical collar and cannot be moved. What type of positioning routine should be performed for this situation?

Trauma horizontal beam lateral, acanthioparietal reverse waters

True/False: A grid is not required for the lateral projection of the nasal bones.

True

True/False: Facial bone studies should be performed erect whenever possible.

True

True/False: Otosclerosis is a hereditary disease.

True

True/False: The CR should be angled as needed to be parallel to the glabellomeatal line (GML) for the superoinferior tangential projection of the nasal bones.

True

True/False: The Schuller method requires that the skull be placed in a true lateral position.

True

The shallow depression just posterior to the base of the dorsum sellae and anterior to the foramen magnum is the __________________________.

clivus

Which small section of bone is located superior to the cribriform plate?

crista galli

Situation: A radiograph of an AP axial (Towne method) projection for the cranium shows that the posterior arch of C1 and the dorsum sellae are superimposed. Both are projected into the foramen magnum. What modification is needed to correct this error that is present on the initial radiograph?

decrease CR angle based on the skull line used, OML 30 degree; IOML 37 degree

A radiograph of a 15-degree PA projection of the facial bones shows that the petrous ridges are projected at the level of the midorbital rims. What specific positioning or CR angling error led to this radiographic outcome?

excessive flexion or insufficient CR angle

What is the name of a prominent landmark (or "bump") found on the external surface of the occipital bone?

external occipital protuberance or inion

True/False: All of the paranasal sinuses except the sphenoid communicate with the nasal cavity.

false, all of the sinuses communicate with the nasal cavity

Which single projection of the facial bones best demonstrates any possible air-fluid levels in the sinuses if the patient cannot stand or sit erect?

horizontal beam lateral projection

Where should the optic foramen be located with a well-positioned "three-point landing" projection?

in the lower outer quadrant of the orbit

Situation: A radiograph of an AP axial projection for the cranium shows that the dorsum sellae is projected superior to the foramen magnum. What must be modified during the repeat exposure to correct this problem?

increase CR angle approximately 7 degree caudad

Which frontal projection of the facial bones best visualizes the region of the maxilla and orbits?

parietoacanthial (Waters) projection

Situation: The same patient as in the previous situation also requires a frontal projection of the skull. The physician wants the projection to demonstrate the frontal bone and to place the petrous ridges in the lower one-third of the orbits, but it has not been determined whether the patient's cervical spine has been fractured, so the patient cannot be moved from a supine position. What should the technologist do to obtain this image?

perform the AP projection with a 15 degree cephalad CR angle to the OML

What is the thickest and densest structure in the cranium?

petrous portion

A radiograph of lateral position for sinuses shows that the greater wings of the sphenoid bone are not superimposed. What specific positioning error is present?

rotation

Situation: A radiograph of a lateral projection of the cranium shows that the greater wings of the sphenoid are not superimposed. What type of positioning error is present on this radiograph?

rotation

Situation: A radiograph of an AP axial (Towne method) for cranium shows that the left petrous portion of the temporal bone is wider than the right. What is the specific positioning error present on this radiograph?

rotation to the right

What is the name of the cranial suture formed by the inferior junction of the parietals to the temporal bones?

squamosal suture

Which aspect of the temporal bone is considered the thinnest?

squamous portion

What is the maximum amount of CR angulation that should be used for an axiolateral oblique projection of the mandible?

25 degrees cephalad

Which positioning line should be perpendicular to the image receptor for the parieto-orbital oblique (Rhese method) projections for optic foramina? A. Acanthomeatal line (AML) B. Mentomeatal line (MML) C. Infraorbitomeatal line (IOML) D. Glabellomeatal line (GML)

A. Acanthomeatal line (AML)

Which of the following imaging modalities best demonstrates bony erosion of the maxillary sinus resulting from acute sinusitis? A. CT B. MRI C. Ultrasound D. Conventional radiography

A. CT

Which of the following imaging modalities may be used to examine a possible cranial bleed caused by trauma? A. CT B. MRI C. Ultrasound D. Nuclear medicine

A. CT

Identify the labeled landmarks and positioning lines used in skull and facial bone positioning, as shown in Fig. 11.30 (including abbreviations).

A. EAM b. Angle (gonion) C. Mentum D. Acanthion E. Nasion F. Glabella G. GAL H. OML I. IMOL J. AML K. LML L. MML

The proper method and projection name for the "three-point landing" projection for the optic foramen is the

Rhese method / parietoorbital oblique

What structures are better defined when the CR angulation is increased from 35 to 40 degrees caudad for the AP axial projection of the mandible?

TM Fossae

True/False: The frontal sinuses are usually larger in men than in women.

True

True/False: The hypophysis cerebri is another term for the pituitary gland.

True

True/False: The sphenoid bone articulates with all the other cranial bones.

True

Situation: A superoinferior, tangential projection for the nasal bones was taken with the following analog exposure factors: 18- × 24-cm (8- × 10-inch) IR portrait, 85 kV, 13 mAs, 40-inch (102-cm) SID. The resultant radiograph was unsatisfactory because of poor visibility of the nasal bones. Which technical factors should be changed for the repeat exposure?

kV is too high, analog needs to be 50 to 60 kV

What is the name of the paired collections of bone found inferior to the cribriform plate that contain numerous air cells and help form the lateral walls of the nasal cavity?

lateral labyrinths

Which aspect of the ethmoid bone contains the ethmoid air cells?

the two lateral labyrinths (masses)

Situation: A radiograph of a lateral skull demonstrates that the orbital plates (roof) of the frontal bone are not superimposed. What is the positioning error present on this radiograph?

tilt of the skull

Why should a patient remain in an erect position for at least 5 minutes before sinus radiography?

to allow time for the thick, gel like fluid to be visualized

True/False: The lateral projection of the nasal bones should be performed using a small focal spot, low-to-medium kV (analog), and close collimation.

true

Situation: A patient comes to the radiology department for a skull series. Because of the size of the patient's shoulders, he is unable to flex his neck sufficiently to place the OML perpendicular to the IR for the AP axial projection. His head cannot be raised because of possible cervical trauma. What other options does the technologist have to obtain an acceptable AP axial projection?

use IOML instead and increase CR angle to an additional 7 degree caudad