Chapter 15 - Spine

Question 1

The spine is divided into five regions:

Answer 1

cervical spine, thoracic spine, lumbar spine, sacrum, and coccyx

Question 2

lordotic curve, or lordosis

Answer 2

A curvature that is convex (bowing outward) anteriorly

Question 3

kyphotic curve, or kyphosis

Answer 3

One that is convex posteriorly

Question 4

scoliosis

Answer 4

An abnormal lateral curvature is called scoliosis and results from rotation of a lordotic and/or kyphotic curve (Fig. 15.3).

Question 5

vertebral arch

Answer 5

It is formed by the pedicles, which attach to the body on either side, and by the laminae posteriorly.

Question 6

transverse processes

Answer 6

Two projections, extending laterally from the junction of the pedicles and lamina,

Question 7

facets

Answer 7

Four articular processes extend superiorly and inferiorly from the junction of the pedicles and lamina. The articular surfaces of these processes are called facets. They articulate with facets on the articular processes of the vertebrae above and below, forming the zygapophyseal joints.

Question 8

intervertebral disks

Answer 8

The vertebrae are cushioned anteriorly, between the bodies, by pads of fibrocartilage

Question 9

annulus fibrosus

Answer 9

a tough outer covering of intervertebral disks

Question 10

nucleus pulposus

Answer 10

a soft, pulpy center of intervertebral disks

Question 11

cervical spine

Answer 11

The cervical spine consists of seven vertebrae and has a lordotic curve. The cervical spinous processes are bifid; that is, they are split into two posterior projections, forming a shape somewhat like a fishtail.

Question 12

atlas

Answer 12

The first cervical vertebra (C1). It is a ringlike structure with no vertebral body and a very short spinous process called the posterior tubercle.

Question 13

axis

Answer 13

The second cervical vertebra (C2). It is the vertebra on which the atlas rotates, allowing the head to turn from side to side.

Question 14

dens, or odontoid process

Answer 14

Superior to the body of the axis is a toothlike projection

Question 15

vertebra prominens

Answer 15

The seventh cervical vertebra (C7), termed the vertebra prominens, has a spinous process that is larger than the others and is easily palpable at the base of the neck.

Question 16

thoracic spine

Answer 16

The thoracic spine is sometimes also referred to as the dorsal spine. It consists of 12 vertebrae and has a kyphotic curve.

Question 17

Intervertebral foramina

Answer 17

The intervertebral foramina of the cervical spine are oriented anteriorly at an angle of 45 degrees to the sagittal plane.

The intervertebral foramina of the thoracic spine lies at an angle of 90 degrees to the sagittal plane and so are seen from the lateral perspective

The intervertebral foramina of the lumbar spine forms an angle of 90 degrees to the sagittal plane and are seen from the lateral perspective

Question 18

zygapophyseal joints

Answer 18

Cervical Spine - With the exception of the C1–C2 articulation, the cervical zygapophyseal joints slope posteriorly and lie in the sagittal plane, so they are best seen from the lateral aspect

Thoracic Spine - The zygapophyseal joints of the thoracic spine are aligned at an angle of 20 degrees posterior to the coronal plane

Lumbar Spine - The zygapophyseal joints lie at an angle of 30 to 60 degrees, open posteriorly, to the sagittal plane.

Question 19

lumbar spine

Answer 19

The lumbar spine consists of five vertebrae and has a lordotic curve. The typical lumbar vertebra (Fig. 15.15) has a large, rounded body and a rather large, flat spinous process.

Question 20

pars interarticularis

Answer 20

The narrow segment of bone between the superior and inferior articular processes

Question 21

Scottie dog

Answer 21

When radiographed in the oblique projection, the lumbar vertebrae demonstrate a configuration that resembles a Scottie dog (Fig. 15.18). The superior articular processes form the ears of the dog, and the inferior articular process forms the front legs. The pars interarticularis corresponds to the dog’s neck.

Question 22

sacrum

Answer 22

At birth, the sacrum consists of five sacral vertebrae. In the adult, they are fused into a solid bony structure (Fig. 15.19).

Question 23

sacroiliac (SI) joints

Answer 23

The sacrum articulates with the ilia of the pelvis on either side

Question 24

alae

Answer 24

The lateral portions of the first sacral segment are winglike structures

Question 25

coccyx

Answer 25

In lay terms, it is called the tailbone. The coccyx usually consists of four small vertebral segments, but it is not unusual for there to be three or five segments. The coccygeal segments tend to fuse in the adult. The coccyx, the most inferior portion of the spine, is approximately the size of the fifth finger.

Question 26

sacrum and coccyx

Answer 26

Together the sacrum and coccyx form a kyphotic curve. This curvature is more pronounced in females than in males.

Question 27

sacral base angle

Answer 27

The sacral base slopes downward anteriorly, and the degree of slope. This angle is greatest in females. It is greater when standing than when recumbent and is least when supine with the knees flexed.

Question 28

typical cervical vertebrae

Answer 28

The third (C3) through sixth (C6) cervical vertebrae are termed the typical cervical vertebrae

Question 29

sacral foramina

Answer 29

The four pairs of sacral foramina are passages for nerves.

Question 30

coccygeal cornua

Answer 30

Two small bony projections extend superiorly from the posterior aspect on each side of the first coccygeal segment.(singular cornu, which means “horn”)

Question 31

sacral cornua

Answer 31

Two small bony projections from the posterior inferior aspect of the sacrum.
(singular cornu, which means “horn”)

Question 32

The most common areas for coned-down radiography are

Answer 32

the upper cervical spine (C1 and C2) and the lumbosacral junction, but it may be helpful in any area of the spine. The limited operator must be able to correctly identify the location of any vertebra when a coned-down radiograph is necessary.

Question 33

AP projection

Answer 33

Two radiographs are necessary to demonstrate the entire cervical spine in the AP projection.

Question 34

The AP axial projection of the lower cervical spine demonstrates C3 through C7, but the lower jaw and the teeth are superimposed over the atlas and axis.

Answer 34

To demonstrate the upper cervical vertebrae, a second AP projection is taken through the open mouth. This projection is sometimes referred to as the AP open-mouth or the odontoid projection.

Question 35

small focal spot

Answer 35

Detail is also enhanced by the use of the small focal spot.

Question 36

For the lateral projection, the inferior margin of the image receptor (IR) must be below the level of the upper surface of the shoulder to demonstrate all of C7.

Answer 36

This results in a large object–image receptor distance (OID) between the neck and the IR. To minimize magnification and improve detail on this projection, a 72-inch source–image receptor distance (SID) is used. Detail is also enhanced by the use of the small focal spot.

Question 37

The routine examination of the cervical spine includes

Answer 37

the AP axial (lower cervical), AP (upper cervical), and lateral projections.

Question 38

AP Axial Projection (Lower Cervical Spine)

Answer 38

SID

40 inches minimum

Body position

Seated, standing, or supine.

Part position

Midsagittal plane of both body and head are aligned perpendicular to center of IR, with patient facing tube. Head position is adjusted so that a line between mental point and base of skull makes an angle of 15 degrees with horizontal plane (Fig. 15.22). When patient is recumbent, patient’s head rests on table (Fig. 15.23). Head is placed firmly against IR holder when upright. If desired position cannot be attained in this way, a radiolucent wedge sponge is placed under/behind head for stability.

Tip

The upper margin of the collimator light field will fall across the patient’s face at an angle of 15 degrees, which simplifies the adjustment of the head position.

Central ray

Centered with regard to IR at an angle of 15 degrees cephalad through thyroid cartilage.

Structures seen

Vertebrae C3 through T2, including bodies, articular pillars, and intervertebral disk spaces (Fig. 15.24).

Question 39

AP Projection/Open Mouth Technique (Upper Cervical Spine)

Answer 39

SID

40 inches minimum (30 inches may be used to increase the odontoid area field of view)

Body position

Seated, standing, or supine.

Part position

Patient faces tube with midsagittal plane of both body and head perpendicular to center of IR. Position of head is adjusted so that a line between lower surface of upper teeth (occlusal plane) and base of skull is parallel to horizontal plane (Figs. 15.25 and 15.26). When patient is upright, patient’s head is placed firmly against IR holder or a radiolucent wedge sponge for stability.

Central ray

Perpendicular to center of IR, through midpoint of open mouth.

Patient instruction

Open mouth as wide as possible. Stop breathing. Do not move.

Tip

If the patient has closed the mouth following positioning and must reopen it before the exposure, it is wise to instruct the patient to “drop the lower jaw” as far as possible. When instructed to “open wide,” patients may tend to extend the neck, which causes incorrect position of the head.

Structures seen

Lateral masses and transverse processes of atlas, dens, and upper half of body of axis, seen between upper and lower teeth (Fig. 15.27).

Tip

If the base of the skull is superimposed on the atlas and the dens, then the patient’s neck was extended too far. If the upper teeth are superimposed on the atlas and the dens, then the patient’s neck was flexed too much. If the lower teeth are superimposed on the upper half of the axis and the base of the skull is in the proper position, the patient’s mouth was not open far enough.

Question 40

Cervical Spine - Lateral Projection (Grandy Method)

Answer 40

SID

60 to 72 inches (152 to 183cm) is recommended because of the increased OID

Body position

Seated or standing.

Part position

Midsagittal planes of body and head are parallel to IR with infraorbitomeatal line parallel to floor. Shoulders must be relaxed and depressed. IR is positioned so that upper margin is about 1 inch above the external auditory meatus (EAM) (Fig. 15.28).

Tip

Patients with high, square shoulders may need to have sandbags of equal weight suspended from the wrists to place the shoulders below C7 (see Fig. 13.104). Alternatively, patient may stand on the center of a long strap, grasping the two ends to maintain downward tension on the shoulders.

Central ray

Perpendicular to center of IR through body of C4.

Tip

Place your finger on the tip of the C7 spinous process and note the location of its shadow in the collimator light beam. It should be within the posterior margin of the IR and at least 2 inches above its inferior margin.

Patient instruction

Stop breathing. Do not move.

Tip

Do not instruct patient to “take a deep breath” because doing so tends to elevate the shoulders.

Structures seen

All seven cervical vertebrae and soft tissues of anterior neck, including spinal alignment, bodies, disk spaces, spinous processes, and zygapophyseal joints (Fig. 15.29).

Note

When a good effort has been made to lower the shoulders for the lateral cervical spine projection but the radiograph fails to demonstrate C7, it is necessary to supplement the examination with the lateral projection of the cervicothoracic region, described later in this chapter.

Question 41

Cervical Spine - LATERAL PROJECTION IN FLEXION AND EXTENSION

Lateral projections with the cervical spine in flexion and extension are performed to evaluate intersegmental stability.

Note

When there has been recent trauma to the cervical spine, the lateral projection in the dorsal decubitus position should be evaluated by the physician before proceeding with flexion and extension lateral projections.

Answer 41

SID

60 to 72 inches (152 to 183cm) is recommended because of the increased OID

Position for flexion

Patient is positioned as for routine lateral projection. Patient is then instructed first to “tuck” chin close to neck and then to flex neck, attempting to look at a spot at midsternum (Fig. 15.30).

Position for extension

Patient is positioned as for routine lateral projection. Patient is then instructed to extend neck, looking at a spot on ceiling directly above head (Fig. 15.31).

Note

The radiographer must not force these positions. The desired degree of flexion or extension is the fullest extent that is tolerable for the patient.

Central ray

Perpendicular to center of IR, through body of C4.

Patient instruction

Stop breathing. Do not move.

Structures seen

All seven cervical vertebrae and soft tissues of anterior neck, including spinal alignment, bodies, disk spaces, spinous processes, and zygapophyseal joints. Head tilted face down in flexion (Fig. 15.32) and tilted face up in extension (Fig. 15.33).

Question 42

Oblique Projections

Answer 42

Oblique projections are taken in left/right pairs. They may be done in a posteroanterior (PA) projection (right anterior oblique [RAO] and left anterior oblique [LAO] positions) or AP projection (right posterior oblique [RPO] and left posterior oblique [LPO] positions).

Question 43

Cervical Spine - Oblique Projection

Answer 43

SID

60 to 72 inches (152 to 183cm) is recommended because of the increased OID

Body position

Seated, standing, or recumbent.

Part position

Coronal plane of body forms angle of 45 degrees with plane of IR. Sagittal plane of skull is perpendicular to coronal plane of body. Have patient elevate and, if necessary, protrude the chin so that mandible does not overlap spine.

Central ray

AP obliques

Angled 15 degrees cephalad to center of IR through body of C4 (Figs. 15.34 and 15.35).

PA obliques

Angled 15 degrees caudad to center of IR through body of C4 (Figs. 15.37 and 15.38).

Patient instruction

Stop breathing. Do not move.

Structures seen

AP obliques demonstrate intervertebral foramina on side farthest from IR (Fig. 15.36). PA obliques demonstrate intervertebral foramina on side nearest IR (Fig. 15.39).

Question 44

Lateral Projection of Cervicothoracic Region

The lateral projection of the cervicothoracic region is commonly called the swimmer’s technique. It is used when routine lateral projections of either the cervical or the thoracic spine fail to demonstrate this area adequately. The shoulder positions create a small “window” between the shoulders, and the cervicothoracic spine is projected into this relatively open area.

Answer 44

SID

40 inches minimum

Body position

Seated, standing, or recumbent.

Part position

Sagittal planes of body and head are parallel to IR. Arm nearest IR is raised above head and shoulder is rounded anteriorly. Opposite shoulder is depressed and slightly posterior (Figs. 15.40 and 15.41).

Central ray

Perpendicular to IR at C7–T1 interspace. Central ray enters at base of neck in midcoronal plane at level of C7 spinous process.

Patient instruction

Stop breathing. Do not move.

Structures seen

Vertebrae C6 through T3 (C5 through T5 with larger IR) in lateral projection without significant rotation. Bodies, disk spaces, spinous processes, and zygapophyseal joints are demonstrated between shoulders (Fig. 15.42).

Tip

Take care when positioning the arms so that the midsagittal plane of the body remains parallel to the IR. The most common error associated with this position is rotation of the body so that the spine is oblique rather than lateral.

Compensating filter

This projection will be improved with the use of a compensating filter because of the extreme difference between the thin lower neck and the very thick upper thoracic region. With the use of a specially designed filter, the C7–T1 area can be more clearly seen.

Question 45

There is significant tissue density variation between the extreme ends of the thoracic spine. Near the neck there is much less tissue to penetrate than at the level of T12 in the upper abdominal region.

Answer 45

For this reason, it is desirable to use the anode heel effect

Question 46

In the thoracic spine - lateral projection, the density variation is reversed. The proximal thoracic spine is more difficult to penetrate because of the bone and muscle mass of the shoulders, and there is little lung tissue in this area. The inferior portion is relatively easily penetrated because its mass is largely air-containing lung.

Answer 46

For this reason, it may be desirable to reverse the position of the compensating filter for the lateral projection. In any case, the first three thoracic vertebrae are seldom visualized well on the lateral projection. When the area of clinical interest includes the upper thoracic vertebrae, it is usual for the examination to include a swimmer’s lateral projection of the cervicothoracic region.

Question 47

The routine examination of the thoracic spine includes

Answer 47

the AP and lateral projections.

Question 48

Thoracic Spine - AP Projection

Answer 48

SID

40 inches minimum

Body position

Seated, standing, or recumbent.

Part position

Midsagittal plane of body is perpendicular to IR and centered on it, with patient facing tube. Superior border of IR is aligned 1.5 to 2 inches (3.8 to 5cm) above the shoulders (Figs. 15.43 and 15.44). When patient is supine, it is helpful to place a bolster under knees. When patient is standing, feet should be shoulder-width apart with equal weight bearing, and patient’s back should be firmly against IR holder.

Central ray

Perpendicular to center of IR at T7. This point is in midline at approximate midpoint of sternum.

Patient instruction

Do not move. Suspend breathing on expiration.

Structures seen

All 12 thoracic vertebrae, particularly the bodies, disk spaces, and transverse processes. C7 and at least a portion of L1 are usually also seen (Fig. 15.45).

Compensating filter

The image quality of this projection can be improved significantly with use of a compensating filter. Various wedge filters are available to assist in providing a uniform density of the entire thoracic spine.

Question 49

Thoracic Spine - Lateral Projection

Answer 49

SID

40 inches minimum

Body position

Seated, standing, or recumbent.

Part position

Sagittal plane of body is parallel to IR. Center the posterior half of the thorax to the midline of the IR. Arms may be raised overhead (Fig. 15.46) or anterior to body with shoulders rounded anteriorly (Fig. 15.47). The superior border of the IR is adjusted to 1.5 to 2 inches (3.8 to 5cm) above the shoulders. Take care that entire length of thoracic spine is parallel to IR. When patient is recumbent, this may require support of a radiolucent sponge under waist and/or hips.

Central ray

Perpendicular to center of IR at level of T7. Central ray enters at inferior angle of scapula through middle of posterior half of thorax.

Tip

Place a strip of lead or a lead rubber mask behind the patient so that its margin is aligned with the shadow of the patient’s back in the collimator light. This absorbs backscatter and improves visualization of the spinous processes.

Patient instruction

Do not move. Perform shallow breathing during exposure.

Tip

A low milliamperage (mA) setting that provides the desired milliampere-seconds (mAs) with an exposure time of 1 to 3seconds is necessary for best results with breathing technique.

Structures seen

T3 through T12 with blurring of ribs and lung markings when breathing technique is used (Fig. 15.48).

Question 50

The routine examination of the lumbar spine includes

Answer 50

the AP or PA and lateral projections.

Question 51

Lumbar Spine - AP or PA Projection

Answer 51

SID

40 inches minimum

Body position

Standing or recumbent.

Part position

AP

Patient faces tube with midsagittal plane perpendicular to IR and centered on it (Fig. 15.49). When patient is supine, knees are flexed and may be supported with a bolster. When patient is standing, feet are shoulder-width apart with equal weight bearing, and torso is stabilized against upright IR holder (Fig. 15.50).

PA

Patient stands facing IR or lies prone, with midsagittal plane perpendicular to IR and centered on it.

Central ray

Perpendicular to center of IR through L4, in midline at level of iliac crest.

Structures seen

All five lumbar vertebrae, intervertebral disk spaces, proximal portion of sacrum, and SI joints. This projection demonstrates the bodies, disk spaces, and transverse processes. The pedicles are seen on end. When a 35-×43-cm IR is used, central pelvis and hip joints may be visualized if collimation is not too close (Figs. 15.51 and 15.52). Visualization of hip joints is particularly important to demonstrate pelvic tilt when an upright AP projection is taken.

Question 52

Lumbar Spine - Lateral Projection

Answer 52

SID

40 inches minimum

Body position

Standing or recumbent.

Part position

Sagittal plane is parallel to IR.

Recumbent

In lateral recumbent position, spine is aligned parallel to center of Bucky with arms anterior to body. Radiolucent sponges may be used to elevate waist and/or hip to keep spine level (Fig. 15.53). Knees are flexed. A pad between knees helps keep pelvis lateral and maintain lateral position of spine.

Upright

Feet are shoulder-width apart with equal weight bearing, and torso is stabilized against upright IR holder. Arms are crossed over chest with hands supported on shoulders. Alternatively, arms may be supported out of radiation field by having patient grasp a pole (Fig. 15.54).

Central ray

Perpendicular to center of IR through L4, in midaxillary line at level of iliac crest.

Tip

Place a strip of lead or a lead rubber mask behind the patient so that its margin is aligned with the shadow of the patient’s back in the collimator light. This absorbs scatter and improves visualization of the spinous processes.

Patient instruction

Do not move. Suspend breathing on expiration. (Respiratory phase is particularly important on the lateral projection. If exposed on inspiration, the posterior lung fields will superimpose the body of L1.)

Structures seen

All five lumbar vertebrae and superior half of sacrum, including intervertebral foramina, spinous processes and profile of the bodies, and intervertebral disk spaces (Fig. 15.55).

Question 53

Lumbar Spine - AP OBLIQUE PROJECTION

Bilateral oblique projections are taken. AP obliques (RPO and LPO positions), rather than PA obliques, are most commonly done because they demonstrate the zygapophyseal joints and pars interarticularis of the side nearest the IR, providing better detail.

Answer 53

SID

40 inches minimum

Body position

Standing or recumbent.

Part position

Sagittal plane is aligned at angle of 45 degrees to IR.

Recumbent

From supine position, patient is rotated 45 degrees toward side being radiographed (Fig. 15.56). Position may be supported by a large 45-degree-angle radiolucent sponge. Take care that the entire spine is rotated the same amount so there is no torsion (twist) of spine.

Upright

From AP position, patient is rotated 45 degrees toward side being radiographed. Feet are shoulder-width apart bearing equal weight, and torso is stabilized against upright IR holder (Fig. 15.57).

Central ray

Perpendicular to center of IR through L3. Central ray enters at point 2 inches medial to anterior superior iliac spine (ASIS) farthest from IR and 1.5 inches superior to iliac crest.

Patient instruction

Do not move. Suspend breathing on expiration.

Structures seen

All five lumbar vertebrae and upper portion of sacrum, including zygapophyseal joints and pars interarticularis on the side nearest the IR (Fig. 15.58).

Question 54

Lateral Projection of L5–S1 Lumbosacral Junction

A coned-down radiograph of the lumbosacral junction in the lateral projection is helpful when there is poor visualization of this area on the routine lateral projection. This may occur as a result of insufficient penetration of this dense area. This projection is important because this junction is a common site of chronic low back pain. Although this projection may be taken with the patient upright, the result is usually superior when the patient is recumbent.

Answer 54

SID

40 inches minimum

Body position

As for routine lateral lumbar projection, with care taken that spine is parallel to IR (Fig. 15.59).

Central ray

Directed perpendicular to center of IR through lumbosacral joint. This centering point is 2 inches posterior to ASIS and 1.5 inches inferior to iliac crest on coronal line midway between ASIS and posterior prominence of sacrum. When spine cannot be supported, angle 5 degrees caudad for males and 8 degrees caudad for females.

Patient instruction

Do not move. Suspend breathing on expiration.

Structures seen

The lower one or two lumbar vertebrae, the upper sacrum, and an open lumbosacral junction (Fig. 15.60).

Question 55

Lumbar Spine and Sacroiliac Joints

AP Axial Projection of Lumbosacral Junction and Sacroiliac Joints

Because of the sacral base angle, the lumbosacral junction is not well seen on the routine AP projection of the lumbar spine. The AP axial projection directs the central ray parallel to the sacral base. See Table 15.1 for variations in sacral base angle. This projection is also useful for demonstration of the SI joints.

Answer 55

SID

40 inches minimum

Body position

Supine, as for AP recumbent lumbar spine, with knees flexed and supported.

Central ray

Angled 30 degrees cephalad for males and 35 degrees cephalad for females. It is directed to center of IR through lumbosacral junction (Fig. 15.61). Central ray enters in midline, 1 inch inferior to the ASIS (Fig. 15.62).

Structures seen

Open lumbosacral junction, sacral alae, and SI joints (Fig. 15.63).

Question 56

The routine examination of the SI joints includes

Answer 56

the AP oblique projections. The AP axial projection of the lumbosacral junction and the SI joints may also be included.

Question 57

Sacroiliac Joints - AP Oblique Projection

Bilateral AP oblique projections are usually taken for comparison.

Answer 57

SID

40 inches minimum

Body position

Recumbent.

Part position

AP obliques (RPO, LPO positions)

From supine position, body is rotated so that coronal plane is aligned at angle of 25 to 30 degrees to IR (Fig. 15.64). The side of interest is elevated, furthest from IR (Fig. 15.65). Position may be supported by radiolucent sponge under hip and lumbar area of elevated side. Take care the entire spine is rotated the same amount so that there is no torsion of spine.

PA obliques (RAO, LAO positions)

From prone position, body is rotated so that coronal plane is aligned at angle of 25 to 30 degrees to IR. Side of interest is nearest the IR. This position may be supported by radiolucent sponge under hip and abdomen area on opposite side. Take care the entire spine is rotated the same amount so that there is no torsion of spine.

Central ray

AP obliques

Perpendicular to center of IR through point 1 inch medial to ASIS farthest from IR.

PA obliques

Perpendicular to center of IR through point 1 inch medial to ASIS nearest the IR.

Patient instruction

Do not move. Suspend breathing on expiration.

Structures seen

AP obliques

SI joint farthest from IR (Fig. 15.66).

PA obliques

SI joint nearest IR.

Question 58

The routine examination of the sacrum includes

Answer 58

the AP axial and lateral projections.

Question 59

Sacrum - AP Axial Projection

Answer 59

SID

40 inches minimum

Body position

Recumbent or supine.

Part position

Midsagittal plane is perpendicular to IR and centered to it. Knees are flexed and supported with a bolster, if needed.

Central ray

Angled 15 degrees cephalad to enter body at midline, 1 inch inferior to the ASIS (Fig. 15.67).

Patient instruction

Stop breathing. Do not move.

Structures seen

Entire sacrum and SI articulations (Fig. 15.68).

Question 60

Sacrum - Lateral Projection

Answer 60

SID

40 inches minimum

Body position

Recumbent.

Part position

Sagittal plane is parallel to IR.

Recumbent

Spine is aligned parallel to center of Bucky with arms anterior to body. Radiolucent sponges may be used to elevate waist and/or hips to keep spine level (Fig. 15.69). Knees are flexed. A pad between knees helps maintain lateral position of pelvis and spine.

Central ray

Perpendicular to center of IR through center of sacrum. Central ray enters at point 3.5 inches posterior to ASIS (Fig. 15.70).

Tip

Place a strip of lead or a lead rubber mask behind the patient so that its margin is aligned with the shadow of the patient’s back in the collimator light. This absorbs backscatter and improves contrast resolution of the sacrum image.

Patient instruction

Do not move. Suspend breathing on expiration.

Structures seen

Entire sacrum and lumbosacral junction (Fig. 15.71). Coccyx is sometimes seen.

Question 61

The routine examination of the coccyx includes

Answer 61

the AP axial and lateral projections.

Question 62

Coccyx - AP Axial Projection

Answer 62

SID

40 inches minimum

Body position

Recumbent.

Part position

Coronal plane is parallel to IR with patient facing tube. Midsagittal plane is centered to midline of Bucky. When patient is supine, knees are flexed and supported with a bolster, if needed.

Central ray

Angled 10 degrees caudad to enter body in midline, 1 inch inferior to the ASIS (Fig. 15.72).

Patient instruction

Do not move.

Structures seen

Entire coccyx and distal portion of sacrum (Fig. 15.73).

Question 63

Coccyx - Lateral Projection

Answer 63

SID

40 inches minimum

Body position

Recumbent.

Part position

Sagittal plane is parallel to IR. When patient is recumbent, knees are flexed and may be separated by a sponge or cushion (Fig. 15.74).

Central ray

Perpendicular to center of IR through center of coccyx. Central ray enters at point 2 inches inferior to ASIS level and 3.5 inches posterior to ASIS.

Tip

Place a strip of lead or a lead rubber mask behind the patient so that its margin is aligned to the shadow of the patient’s back in the collimator light. This absorbs backscatter and improves contrast resolution of the coccyx image.

Patient instruction

Do not move.

Structures seen

Entire coccyx and distal portion of sacrum (Fig. 15.75).

Question 64

Full Spine - PA or AP Projection (Frank et al. Method)

Answer 64

SID

60 inches minimum

Position

Upright as for standing PA lumbar spine projection. Height of grid and IR is adjusted to include area from top of patient’s ears to level of greater trochanters (Fig. 15.76). Head is positioned as for AP axial projection of upper cervical spine, with neck extended slightly to allow for angulation of diverging x-ray beam at upper extreme of exposure field.

Central ray

Aligned perpendicular to center of IR, entering at midline approximately at level of xiphoid process.

Patient instruction

Stop breathing. Do not move.

Structures seen

Portion of mandible, entire spine, portion of pelvis (Figs. 15.77 and 15.78).

Compensating filter

The wide range of body part thicknesses and tissue densities in the thoracic and abdominal areas necessitates the use of specially designed compensating filters to create a more uniform radiographic brightness throughout the entire spine.

Question 65

Full Spine - Lateral Projection

Answer 65

SID

60 inches minimum

Position

Same as for upright lateral projection of thoracic spine. Shoulders are rounded anteriorly and arms are extended anterior to body and supported (Fig. 15.79).

Patient instruction

Stop breathing. Do not move.

Structures seen

Portion of mandible and skull, entire spine, portion of pelvis (Fig. 15.80).

Compensating filter

The wide range of body part thicknesses and tissue densities in the thoracic and abdominal areas necessitates the use of specially designed compensating filters to create a more uniform radiographic density (brightness) throughout the entire spine.

Question 66

sacralization of L5

Answer 66

Sometimes one or both spinous processes of L5 become fused to the sacrum

Question 67

spina bifida occulta

Answer 67

Usually spina bifida is relatively insignificant and produces no symptoms,

Question 68

spina bifida vera

Answer 68

Less commonly, the defect may be quite large, leaving the spinal cord unprotected;

Question 69

pathologic fractures

Answer 69

In bones weakened by disease processes, fractures may occur with little or no trauma.

Question 70

Pathologic compression fractures of the thoracic spine caused by osteoporosis

Answer 70

are often seen in elderly women (Fig. 15.86).

Question 71

Spondylosis

Answer 71

refers to fixation or fusion of vertebrae.

Question 72

Spondylitis

Answer 72

has the suffix -itis, which you may recall indicates inflammation. This term is often applied specifically to tuberculous disease of the vertebrae, which is also called Pott disease. Spondylitis is also seen with rheumatoid arthritis.

Question 73

Spondylolysis

Answer 73

refers to the breakdown of the structure of the bone. This occurs with osteoporosis, with some metastatic lesions, and with other conditions that cause atrophy and bony destruction.

Question 74

Spondylolisthesis

Answer 74

refers to the anterior displacement of one vertebra on another (Fig. 15.90). It occurs most commonly at the lumbosacral joint and is usually caused by a defect or a fracture of the pars interarticularis or of the pedicle.

Question 75

Spondyloschisis

Answer 75

is the term for a congenital fissure (split or cleft) in the neural arch.

Question 76

degenerative disk disease (DDD)

Answer 76

With advancing age and repeated minor traumas to the spine, the disks tend to degenerate. The nucleus may dry out and become atrophied, which causes narrowing of the disk space. Without adequate cushioning, the joint becomes inflamed, and the surrounding bony structures show the characteristic signs of degeneration: sclerotic (hardened), irregular bone margins with hypertrophic lipping and spurring. This condition is called degenerative disk disease (DDD) and is usually associated with osteoarthritis.

Question 77

Disk herniation or herniated nucleus pulposus (HNP)

Answer 77

is the condition often called, in lay terms, a slipped disk.

The annulus fibrosus ruptures, and the nucleus is forced into the area posterior to the disk space (Fig. 15.92). The displaced nucleus causes pressure on the spinal cord and/or the nerve roots in this area.

Question 78

Disk herniation

Answer 78

Disk herniation may cause acute pain, chronic discomfort, or recurrent painful episodes involving the site of the herniation. There may also be pain, numbness, or altered sensation in areas remote from the spine.

Question 79

disk pathology

Answer 79

Myelography, discography, computed tomography, and magnetic resonance imaging studies (Fig. 15.93) may be used to identify disk pathology.

Question 80

Sciatica

Answer 80

pain along the path of the sciatic nerve in the buttock, posterior thigh, and leg. It is caused by nerve irritation in the lumbar region. Damage to nerve roots may cause weakness or paralysis. The function or control of organs may be affected as well.

Question 81

stenosis

Answer 81

narrowing of the intervertebral foramina

Question 82

33 vertebrae or spinal segments:

Answer 82

7 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 4 coccygeal.

Question 83

Most vertebrae consist of

Answer 83

an anterior body, a posterior vertebral arch, two lateral projections called transverse processes, and a posterior projection called the spinous process.