2.1 Procedures - Head

Question 1

What is the anatomic structure indicated by number 3 in the radiograph in Figure 6–20?

A - Angle of the mandible
B - Coronoid process
C - Condyloid process
D - Zygomatic arch

Answer 1

B - Coronoid process

A parietoacanthial projection (Waters position) of the skull is shown. The chin is elevated sufficiently to project the petrous ridges below the maxillary sinuses. The zygomatic arch is well demonstrated, as are the mandible, its angle, and the coronoid process. The coronoid process corresponds to the structure labeled number 3.

Question 2

In Figure A, which of the localization lines is used for the lateral projection of the skull?

A - Line 1
B - Line 2
C - Line 3
D - Line 4

Answer 2

C - Line 3

The lateral projection of the skull requires that the patient be in the prone oblique position with the MSP parallel to the IR and the interpupillary line perpendicular to the IR. The IOML (line 3) must be parallel to the long axis of the IR and perpendicular to the front edge of the IR. The supraorbital margins, anterior clinoid processes, and posterior clinoid processes should be superimposed.

Question 3

The most common skull positioning errors include the following

A - Rotation
B - Incorrect CR angulation
C - Both
D - Neither

Answer 3

C - Both

Precise positioning, centering, and angulation are required for quality skull imaging. The radiographer must use the appropriate baseline, tube angulation, CR direction and path, etc. The most common skull positioning errors include tilt, rotation, incorrect CR angulation, and excessive neck flexion or extension.

Question 4

Which of the following would best evaluate the structure labeled 4 in Figure 2–14?

A - PA axial projection (Caldwell method)
B - Parietoacanthial projection (Waters method)
C - Lateral projection
D - Submentovertebral projection

Answer 4

B - Parietoacanthial projection (Waters method)

The figure illustrates an anatomic lateral view of the paranasal sinuses. Number 1 points to the frontal sinuses and number 2 to the ethmoidal sinuses; both can be visualized using the PA axial projection (Caldwell method). Number 3 is the sphenoidal sinuses, which are well demonstrated in the SMV projection. Number 4 is the maxillary sinuses, which are best demonstrated using the parietoacanthial projection (Waters method). The lateral projection demonstrates the four pairs of paranasal sinuses superimposed on each other.

Question 5

All the following statements regarding an exact PA projection of the skull are true except

A - the orbitomeatal line is perpendicular to the IR.
B - the petrous pyramids fill the orbits.
C - the midsagittal plane (MSP) is parallel to the IR.
D - the central ray is perpendicular to the IR.

Answer 5

C - the midsagittal plane (MSP) is parallel to the IR.

In the exact PA projection of the skull, the CR is perpendicular and the petrous pyramids should fill the orbits. As the CR is angled caudally, the petrous ridges/pyramids are projected lower in the orbits. At about 25 to 30 degrees caudad they are projected below the orbits. The OML must be perpendicular to the IR for the petrous pyramids to be projected into the expected location, that is, superimposed within the orbits. The MSP must be perpendicular to the IR, or the skull will be rotated and left/right symmetry will be lost.

Question 6

If your patient is unable to maintain an erect position, which one of the following could be useful to evaluate paranasal sinuses?

A - Recumbent AP
B - Lateral recumbent
C - Lateral cross-table recumbent
D - Recumbent Waters’

Answer 6

C - Lateral cross-table recumbent

Radiography of the paranasal sinuses should be performed in the erect position whenever possible to demonstrate the presence of an air-fluid level. The only way air-fluid levels can be demonstrated is to have the central ray parallel the floor, as in erect, decubitus, and cross-table projections. Therefore, of the choices provided, the cross-table lateral is the only one that will demonstrate air-fluid levels.

Question 7

The hard palate is formed by the

1. ethmoid bone.
2. maxillary bone.
3. palatine bone.

A - 1 only
B - 1 and 2 only
C - 2 and 3 only
D - 1, 2, and 3

Answer 7

C - 2 and 3 only

The maxillae are the second largest of the facial bones. They articulate with each other to form most of the upper jaw (hard palate). The palatine bones are small bones, forming the posterior one-third of the hard palate. They are L-shaped, and have vertical and horizontal processes. The horizontal parts articulate with the palatine processes of the maxillae to complete the hard palate. The vertical parts project superiorly from the horizont

Question 8

Which of the four baselines illustrated in Figure 6–15 should be used for a lateral projection of facial bones?

A - Baseline 1
B - Baseline 2
C - Baseline 3
D - Baseline 4

Answer 8

C - Baseline 3

The infraorbitomeatal baseline (IOML) is an imaginary line extending from the infraorbital margin to the external auditory meatus and is represented by number 3. The IOML is used for most lateral skull projections, including lateral projections of facial bones. The skull is positioned so that the MSP is parallel to the IR, the interpupillary line is perpendicular to the IR, and the IOML is perpendicular to the front edge of the IR. Number 1 is the glabellomeatal line, number 2 is the OML (orbitomeatal line), and number 4 is the acanthomeatal line. These baselines are used to obtain accurate positioning in skull radiography.

Question 9

The structures forming the brain stem include

1. the pons
2. the medulla oblongata
3. the midbrain

A - 1 and 2 only
B - 1 and 3 only
C - 2 and 3 only
D - 1, 2, and 3

Answer 9

D - 1, 2, and 3

The brain generally is described as having three divisions. The forebrain is composed of the cerebrum, the thalamus, and the hypothalamus. The midbrain is a short, constricted portion connecting the forebrain to the hindbrain and containing the corpora quadrigemina and the aqueduct of Sylvius. The hindbrain is composed of the pons, medulla oblongata, and cerebellum. The brain stem is defined as the midbrain, pons, and medulla oblongata.

Question 10

Which of the following statements is (are) correct regarding the parietoacanthial projection (Waters’ method) of the skull?

1. The head is rested on the extended chin.
2. The orbitomeatal line (OML) is perpendicular to the IR.
3. The maxillary antra should be projected above the pars petrosa.

A - 1 only
B - 1 and 2 only
C - 1 and 3 only
D - 1, 2, and 3

Answer 10

C - 1 and 3 only

The parietoacanthial projection (Waters’ position) of the skull is valuable for the demonstration of facial bones or maxillary sinuses. The head is rested on the extended chin so that the OML forms a 37° angle with the IR. This projects the petrous pyramids/pars petrosa below the floor of the maxillary sinuses and provides an oblique frontal view of the facial bones.

Question 11

When evaluating a PA axial projection of the skull with a 15-degree caudal angle, the radiographer should see

1. petrous pyramids in the lower third of the orbits
2. equal distance from the lateral border of the skull to the lateral rim of the orbit bilaterally
3. symmetrical petrous pyramids

A - 1 an

Answer 11

D - 1, 2, and 3

A PA axial projection of the skull with a 15-degree caudad angle will show the petrous pyramids in the lower third of the orbits. If no angulation is used, the petrous pyramids will fill the orbits. Either PA projection should demonstrate symmetrical petrous pyramids and an equal distance from the lateral border of the skull to the lateral border of the orbit on both sides. This determines that there is no rotation of the skull.

Question 12

Which of the following positions is/are most frequently used to demonstrate the sphenoid sinuses?

1. Modified Waters (mouth open)
2. Lateral
3. PA axial

A - 1 only
B - 1 and 2 only
C - 2 and 3 only
D - 1, 2, and 3

Answer 12

B - 1 and 2 only

The parietoacanthial (Waters method) projection demonstrates the maxillary sinuses. The modified Waters position, with the central ray directed through the open mouth, will demonstrate the sphenoid sinuses through the open mouth. The PA axial projection demonstrates the frontal and ethmoidal sinus groups. The lateral projection, with the central ray entering 1 inch posterior to the outer canthus, demonstrates all the paranasal sinuses. X-ray examinations of the sinuses always should be performed erect to demonstrate leveling of any fluid present.

Question 13

Which of the following projections can be used to demonstrate pathology of the zygomatic arch?

1. Submentovertebral (SMV) projection
2. Oblique inferosuperior tangential projection
3. PA axial Caldwell projection

A - 1 and 2 only
B - 1 and 3 only
C - 2 and 3 only
D - 1, 2, and 3

Answer 13

A - 1 and 2 only

The zygomatic arches can be difficult anatomical structures to capture on radiographs. Typical positioning utilized for projections of the zygoma is uncomfortable for patients, especially after trauma. Views to obtain the zygomatic arches include the submentovertebral (SMV) projection and oblique inferosuperior projections—both require patients to hyperextend their necks until the IOML is parallel to the IR, thus projecting the zygomatic arches free of superimposition. Additional and less uncomfortable projections include the AP axial Towne method and parietoacanthial (Waters) projections. The PA axial Caldwell proje

Question 14

Referring to Figure 2–38, which of the following positions requires that baseline number 3 be parallel to the IR?

A - Parietoacanthial
B - PA axial (Caldwell)
C - AP axial (Towne)
D - SMV

Answer 14

D - SMV

The SMV projection of the skull requires that the patient’s neck be extended, placing the vertex adjacent to the IR holder/upright Bucky so that the IOML is parallel with the IR. This projection is useful for demonstrating the ethmoidal and sphenoidal sinuses, pars petrosae, mandible, and foramina ovale and spinosum. The lateral projection of the skull requires that the patient be in the prone oblique position with the MSP parallel to the IR and the interpupillary line perpendicular to the IR. This position also requires that the IOML (line 3) be parallel to the long axis of the IR. The AP and PA axial projections of the skull require the OML or IOML to be perpendicular to the IR.

Question 15

Structures involved in blowout fractures include the

1. orbital floor
2. inferior rectus muscle
3. temporal bone

A - 1 only
B - 1 and 2 only
C - 2 and 3 only
D - 1, 2, and 3

Answer 15

B - 1 and 2 only

The orbital floor of the adult is comprised of the zygoma, palatine, and maxilla. Blowout fractures of the orbital floor are caused by a direct blow to the eye. The orbital floor collapses, this carrying the inferior rectus muscle through the fracture site and into the maxillary sinus. Diplopia (double vision) often results. Blowout fractures are well demonstrated with the modified Waters method (modified parietoacanthial projection) and with CT studies. A modified parietoacanthial projection with the lips-meatal line (LML) perpendicular and the OML 55 degrees to the IR will demonstrate the orbital floor. The zygoma usually is not involved with a blowout fracture but rather with a tripod fracture.

Question 16

Which of the following statements is (are) true regarding a PA axial projection of the paranasal sinuses?

1. The OML is elevated 15 degrees from the horizontal.
2. The petrous pyramids completely fill the orbits.
3. The frontal and ethmoidal sinuses are visualized.

A - 1 only
B - 1 and 2 only
C - 1 and 3 only
D - 1, 2, and 3

Answer 16

C - 1 and 3 only

The PA axial (Caldwell) projection of the paranasal sinuses is used to demonstrate the frontal and ethmoidal sinuses. The patient’s skull is placed PA, and the OML is elevated 15 degrees from the horizontal. This projects the petrous pyramids into the lower third of the orbits, thus permitting optimal visualization of the frontal and ethmoidal sinuses.

Question 17

Which of the following skull positions will demonstrate the cranial base, sphenoidal sinuses, atlas, and odontoid process?

A - AP axial
B - Lateral
C - Parietoacanthial
D - Submentovertebral (SMV)

Answer 17

D - Submentovertebral (SMV)

The SMV projection is made with the patient’s head resting on the vertex and the central ray directed perpendicular to the IOML. This position may be used as part of a sinus survey to demonstrate the sphenoidal sinuses or as a view of the cranial base for the basal foramina, especially the foramina ovale and spinosum. It also demonstrates the bony part of the auditory (eustachian) tubes. AP or PA axial projections are used frequently to demonstrate the occipital region or evaluate the sellar region. A lateral projection is usually part of a routine skull evaluation. The parietoacanthial projection is the single best position to demonstrate facial bones.

Question 18

The auditory, or eustachian, tube extends from the nasopharynx to the

A - external ear.
B - middle ear.
C - inner ear.
D - oropharynx.

Answer 18

B - middle ear.

The auditory, or eustachian, tube extends from the middle ear to the nasopharynx. It is 3–4 cm in length and is lined with mucous membrane. Otitis media can result when the auditory tube becomes occluded during inflammatory processes. The middle ear contains the auditory ossicles (i.e., malleus, incus, and stapes). The inner ear contains the cochlea, semicircular canals, and vestibule.

Question 19

Glossitis refers to inflammation of the

A - epiglottis
B - salivary glands
C - tongue
D - ossicles

Answer 19

C - tongue

Inflammation of the tongue is called glossitis. Inflamed salivary glands are usually referred to with reference to the affected gland, as in parotitis (inflammation of the parotid gland). Inflammation of the epiglottis is termed epiglottitis.

Question 20

What is the anatomic structure indicated by number 1 in the radiograph shown in Figure 6–20?

A - Mandibular angle
B - Coronoid process
C - Zygomatic arch
D - Maxillary sinus

Answer 20

A - Mandibular angle

A parietoacanthial projection (Waters position) of the skull is shown. The chin is elevated sufficiently to project the petrous ridges below the maxillary sinuses (number 4). Note that the foramen rotundum is seen near the upper margin of the maxillary sinuses. Other paranasal sinus groups are not well visualized in this position, although a modification with the mouth open may be taken to demonstrate the sphenoidal sinuses. This is also the single best projection to demonstrate the facial bones. The zygomatic arch (number 2) is well demonstrated; the mandible, its angle (number 1), and the coronoid process (number 3) are also well demonstrated. The odontoid process is seen projected through the foramen magnum. The mastoid air cells are seen adjacent to the mandibular angle as multiple small, air-filled, bony spaces.

Question 21

The structure labeled 3 in Figure 2–14 is the

A - maxillary sinus
B - sphenoidal sinus
C - ethmoidal sinus
D - frontal sinus

Answer 21

B - sphenoidal sinus

Figure 2–14 illustrates an anatomic lateral view of the paranasal sinuses. Number 1 points to the frontal sinuses and number 2 to the ethmoidal sinuses; both can be visualized using the PA axial projection (Caldwell method). Number 3 is the sphenoidal sinuses, which are well demonstrated in the SMV projection. Number 4 is the maxillary sinuses, which are best demonstrated using the parietoacanthial projection (Waters method). The lateral projection demonstrates the four pairs of paranasal sinuses superimposed on each other.

Question 22

Which of the following are benefits of providing waist support for the recumbent lateral thoracic spine:

(1) The support helps bring the lower and upper thoracic vertebrae to the same distance from the table
(2) Using a support reduces vertebral tilt
(3) Scatter reduction

A - 2 only
B - 1 and 2 only
C - 1 and 3 only
D - 1, 2 and 3

Answer 22

B - 1 and 2 only

When imaging the lateral thoracic spine in a recumbent position, adding a support sponge below the waist can help even out the OID between both the upper and lower vertebrae and the table. In bringing the vertebrae to the same level, tilt is also reduced. The sponge will not, however, supply a reduction in scatter; a lead mat placed posteriorly to the spine can help in scatter reduction.

Question 23

In the example radiograph below of the cross-table hip projection, which number represents the lesser trochanter?

A - 2
B - 5
C - 4
D - 1

Answer 23

C - 4

The labeled structures in the radiograph are identified as follows: number 1 represents the femoral neck, number 2 the greater trochanter, number 3 the ischial tuberosity, number 4 the lesser trochanter, and number 5 the acetabulum.

Question 24

To demonstrate the mandibular body in the PA position, the

A - CR is directed perpendicular to the IR.
B - CR is directed cephalad to the IR.
C - skull is obliqued away from the affected side.
D - skull is obliqued toward the affected side.

Answer 24

A - CR is directed perpendicular to the IR.

The straight PA projection (0 degrees), with the central ray directed perpendicular to the IR, effectively demonstrates the mandibular body. In this position, the rami and condyles are superimposed on the occipital bone and petrous portion of the temporal bone. To better visualize the rami and condyles, the central ray is directed cephalad 20 to 30 degrees.

Question 25

What is the degree of difference between the baselines number 2 and 3 in Figure 2–38 and used for various projections of the skull? A - 7 degrees B - 12 degrees C - 15 degrees D - 23 degrees

Answer 25

A - 7 degrees Accurate positioning of the skull requires the use of several baselines. In the figure, line 1 represents the glabellomeatal line (GML), line 2 is the orbitomeatal line (OML), line 3 is the infraorbitomeatal line (IOML), and line 4 is the acanthomeatal line (AML). The OML and the IOML are separated by about 7 degrees, while the OML and the GML are generally separated by 8 degrees. Therefore, there is a 15-degree difference between the GML and the IOML. It is useful to remember these differen

Question 26

Which of the following statements is (are) true regarding the PA axial projection (Caldwell) of the cranium? 1. The central ray is directed caudally to the OML. 2. The petrous pyramids are projected into the lower third of the orbits. 3. The frontal sinuses are visualized. A - 1 only B - 1 and 2 only C - 1 and 3 only D - 1, 2, and 3

Answer 26

D - 1, 2, and 3 The PA axial (Caldwell) projection of the cranium can be used to demonstrate the frontal and ethmoid bones and the frontal and ethmoidal sinuses. The central ray is angled caudally 15 degrees to the OML. This projects the petrous pyramids into the lower one third of the orbits, thus permitting optimal visualization of the frontal and ethmoidal sinuses. If the paranasal sinuses are being investigated, the OML forms a 15-degree angle with the horizontal central ray. Additionally, the vertical grid should be angled 15 de

Question 27

The radiographic position illustrated in Figure 6–18 is used to demonstrate A - ethmoidal and frontal sinuses. B - maxillary sinuses. C - sphenoidal sinuses through the open mouth. D - mastoid sinuses.

Answer 27

A - ethmoidal and frontal sinuses. A PA axial Caldwell position is shown, demonstrating the frontal and ethmoidal sinuses. The Caldwell position requires an angle of 15 degrees caudad, exiting the nasion. The petrous ridges should be projected in the lower third of the orbits. The radiograph shown demonstrates somewhat excessive angulation because the petrous pyramids are projected at the bottom of the orbits. The maxillary sinuses are demonstrated in the parietoacanthial projection (Waters position), and the sphenoidal sinuses are demonstrated through the open mouth in a modified Waters position. The mastoid sin

Question 28

With the patient's head in a PA position and the CR directed 20 degrees cephalad, which part of the mandible will be best visualized? A - Symphysis B - Rami C - Body D - Angle

Answer 28

B - Rami With the patient in the PA position, the rami are well visualized with a perpendicular ray or with 20 to 25 degrees of cephalad angulation. A portion of the mandibular body is demonstrated in this position, but most of it is superimposed over the cervical spine.

Question 29

Which of the following positions demonstrates all the paranasal sinuses? A - Parietoacanthial B - PA axial C - Lateral D - True PA

Answer 29

C - Lateral The parietoacanthial (Waters' method) projection demonstrates the maxillary sinuses. The PA axial with a caudal central ray (Caldwell) demonstrates the frontal and ethmoidal sinus groups. The lateral projection, with the central ray entering 1 inch posterior to the outer canthus, demonstrates all the paranasal sinuses. X-ray examinations of the sinuses should always be performed erect to demonstrate leveling of any fluid present.

Question 30

Which of the following are required for the AP axial projection of L5-S1: (1) CR 25° cephalic for females (2) Centering at the ASIS (3) Support under the knees for comfort and reduction of pelvic tilt A - 2 only B - 1 and 2 only C - 2 and 3 only D - 1, 2, and 3

Answer 30

C - 2 and 3 only For the AP axial projection of the lumbar spine, the goal is to open the joint space between L5 and S1. The central ray is centered at the level of the ASIS with the patient’s knees flexed to provide comfort. Alternatively, a support cushion can be provided under the knees. A cephalic angulation of 30° for males and 35° for females is needed for adequate joint space opening.

Question 31

Which of the following refers to parts nearer the point of attachment, point of reference, origin, or beginning? A - Distal B - Lateral C - Medial D - Proximal

Answer 31

D - Proximal The term proximal refers to anatomical parts nearer the point of attachment, point of reference, origin, or beginning. Distal refers to anatomical parts farthest from the point of attachment, point of origin, or beginning. Lateral refers to anatomical parts away from the mid-sagittal plane of the body or away from the midline of another body part to the right or left. Medial refers to anatomical parts toward the mid-sagittal plane of the body or toward the middle of another body part.

Question 32

Which of the following statements is (are) true regarding the PA axial projection of the paranasal sinuses? 1. OML forms a 15 degree angle with the horizontal beam. 2. The petrous pyramids are projected into the lower third of the orbits. 3. The frontal sinuses are visualized. A - 1 only B - 1 and 2 only C - 1 and 3 only D - 1, 2, and 3

Answer 32

D - 1, 2, and 3 The PA axial projection of the paranasal sinuses is used to demonstrate the frontal and ethmoidal sinuses. The patient is positioned with the OML 15° to the horizontal central ray, with the chin elevated slightly. This projects the petrous pyramids into the lower third of the orbits, thus permitting optimal visualization of the frontal and ethmoidal sinuses. Central ray angulation should not be used in sinus radiography because it can distort or obliterate existing air-fluid levels.

Question 33

The floor of the cranium includes all the following bones except A - the temporal bones B - the occipital bone C - the ethmoid bone D - the sphenoid bone

Answer 33

B - the occipital bone The skull is divided into two parts—the 8 cranial bones and 14 facial bones. The cranial bones are divided into two parts: calvarium (skullcap) and floor. Only parts of four bones comprise the calvarium (skull cap)—the frontal, the two parietals, and the occipital. The bones that comprise the floor of the cranium are the two temporals, the ethmoid, and the sphenoid.

Question 34

A properly positioned PA axial (Caldwell) projection of the skull directs the central ray: A - 15 to 20 degrees cephalad, exiting the acanthion. B - 10 to 15 degrees caudal, exiting the nasion. C - 10 to 15 degrees caudal, exiting the glabella. D - 30 degrees caudal, entering the nasion.

Answer 34

B - 10 to 15 degrees caudal, exiting the nasion. For the PA axial projection (Caldwell method), the central ray is directed to exit the nasion at an angle of approximately 15 degrees caudad. The other choices, while similar in wording, are incorrect. The modified Towne projection for zygomatic arches enters the nasion at a 30-degree caudal angle, as described in choice D. Choices A and C do not correspond to any standard diagnostic projection.

Question 35

For the lateral thoracic spine breathing technique, how long of an exposure is needed to adequately blur out overlying ribs and lung markings? A - 2–3 seconds B - 4–5 seconds C - 6–8 seconds D - 9–10 seconds

Answer 35

A - 2–3 seconds Breathing technique for the lateral thoracic spine can be useful in demonstrating pathology of the vertebrae by blurring out lung markings and overlying ribs. This technique, if a patient can cooperate, only requires a 2–3 second exposure time. The technique also requires a low mA setting due to the longer exposure.

Question 36

In the AP axial projection (Towne method) of the skull, with the CR directed 30 degrees caudad to the orbitomeatal line (OML) and passing midway between the external auditory meati, which of the following is best demonstrated? A - Occipital bone B - Frontal bone C - Facial bones D - Basal foramina

Answer 36

A - Occipital bone The AP axial projects the anterior structures (frontal and facial bones) downward, thus permitting visualization of the occipital bone without superimposition (Towne method). The dorsum sella and posterior clinoid processes of the sphenoid bone should be visualized within the foramen magnum. This projection may also be obtained by angling the CR 30 degrees caudad to the OML. The frontal bone is best shown with the patient PA and with a perpendicular CR. The parietoacanthial projection is the single best position for facial bones. Basal foramina are well demonstrated in the submentovertebral

Question 37

Which of the following sinus groups is best demonstrated with the patient positioned as for a parietoacanthial projection (Waters method) with the CR directed through the patient's open mouth? A - Frontal B - Ethmoidal C - Maxillary D - Sphenoidal

Answer 37

D - Sphenoidal This is a modification of the parietoacanthial projection (Waters method) in which the patient is requested to open the mouth, and then the skull is positioned so that the OML forms a 37-degree angle with the IR. The central ray is directed through the sphenoidal sinuses and exits the open mouth. The routine parietoacanthial projection with the mouth closed is used to demonstrate the maxillary sinuses projected above the petrous pyramids. The frontal and ethmoidal sinuses are best visualized in the PA axial position (modified Caldwell method).

Question 38

Which of the following methods was most likely used to obtain the image seen in Figure 2–6? A - erect PA, chin extended, OML forming 37 degrees to IR B - erect PA, OML, and CR perpendicular to IR C - erect PA, chin extended, OML 15 degree from horizontal D - erect PA, chin extended, OML 30 degree from horizontal

Answer 38

C - erect PA, chin extended, OML 15 degree from horizontal The radiograph shown is a PA projection (Caldwell method) of the frontal and anterior ethmoidal sinuses. The frontal sinuses are seen centrally in the vertical plate of the frontal bone behind the glabella and extending laterally over the superciliary arches. The ethmoidal sinuses are seen adjacent and inferior to the medial aspect of the orbits. The patient is positioned PA erect with the chin extended so that the OML is elevated 15 degrees from the horizontal. The petrous

Question 39

Which of the following structures is illustrated by the number 2 in Figure 2–21? A - Maxillary sinus B - Coronoid process C - Zygomatic arch D - Coracoid process

Answer 39

C - Zygomatic arch The parietoacanthial projection (Waters method) demonstrates a distorted view of the frontal and ethmoidal sinuses. The maxillary sinuses (number 4) are well demonstrated, projected free of the petrous pyramids. This is also the best single position for the demonstration of facial bones. The mandibular angle is illustrated by number 1, the zygomatic arch by number 2, and the coronoid process by number 3.

Question 40

With an adult patient in the PA position and the OML perpendicular to the IR, a 15- to 20-degree caudal angulation places the petrous ridges in the lower third of the orbit. To achieve the same result in a small child, under 8 years of age, the CR is directed A - perpendicular to the nasion B - 25 to 30 degrees caudal C - 15 to 20 degrees cephalic D - 3 to 5 degrees caudal

Answer 40

A - perpendicular to the nasion With an adult patient in the PA position and the OML perpendicular to the IR, a 15- to 20-degree caudal angulation places the petrous ridges in the lower third of the orbit. To achieve the same result in a small child, whose skull bones are undergoing complex ossification processes, the central ray is simply directed perpendicular to the nasion.

Question 41

What should be done to better demonstrate the mandibular rami seen in PA projection in Figure A? A - use a perpendicular CR B - angle the CR cephalad C - angle the CR caudad D - oblique the head 15° medial

Answer 41

B - angle the CR cephalad Figure A shows a PA projection of the mandible. The head is positioned PA with the OML perpendicular to the IR. The mandibular body is well demonstrated in this position. With the patient in the PA position, the rami can be better demonstrated with 20° to 25° cephalad angulation. A caudal angle could be employed if the skull were positioned in the AP position.

Question 42

Which of the following positions/projections of the skull will result in the most shape distortion? A - 0° PA B - 23° Caldwell C - 37° Towne D - 25° Haas

Answer 42

C - 37° Towne Accurate positioning skills include a knowledge of anatomy (the position of the structure with respect to the image receptor) and geometric principles (how the x-ray tube angle will project or distort the anatomic structure). Shape distortion is related to the alignment of the x-ray tube, the object being examined, and the image receptor. When all three are parallel to one another, shape distortion is minimal. If one or more are out of alignment, shape distortion occurs. The two types of shape distortion are foreshortening and elongation. Foreshortening occurs as a result of the anatomic structure within the body being at an angle with the image receptor. Elongation occurs as

Question 43

With the patient in the PA position and the OML and CR perpendicular to the IR, the resulting radiograph will demonstrate the petrous pyramids A - below the orbits B - in the lower third of the orbits C - completely within the orbits D - above the orbits

Answer 43

C - completely within the orbits For the PA projection of the skull, the OML is adjusted perpendicular to the IR, and the MSP must be perpendicular to the IR. The central ray is directed to exit the nasion. In this position, the petrous pyramids should completely fill the orbits. When caudal angulation is used with this position, the petrous pyramids are projected into the lower portion of, or out of, the orbits. If cephalad angulatio

Question 44

The junction of articulation between the lambdoidal suture and the squamosal suture exists between what bones? A - At junction of the occipital, frontal, and temporal B - At junction of the frontal, parietal, and occipital C - At junction of the parietal, and just behind the coronal suture line D - At junction of the temporal, parietal, and occipital

Answer 44

D - At junction of the temporal, parietal, and occipital The bones of the cranial vault are joined by fibrous joints called sutures, which are classified as synarthrodial joints in the adult. The sutures are named based upon their anatomical location. Between the occipital bone and parietal bones lies the lambdoidal suture. Between the temporal bones and parietal bones lies the squamosal suture. Between the two parietal bones lies the sagittal suture. Between the frontal bone and parietal bones lies the coronal suture.