Chapter 15 - Spine Flashcards
The spine is divided into five regions:
cervical spine, thoracic spine, lumbar spine, sacrum, and coccyx
lordotic curve, or lordosis
A curvature that is convex (bowing outward) anteriorly
kyphotic curve, or kyphosis
One that is convex posteriorly
scoliosis
An abnormal lateral curvature is called scoliosis and results from rotation of a lordotic and/or kyphotic curve (Fig. 15.3).
vertebral arch
It is formed by the pedicles, which attach to the body on either side, and by the laminae posteriorly.
transverse processes
Two projections, extending laterally from the junction of the pedicles and lamina,
facets
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.
intervertebral disks
The vertebrae are cushioned anteriorly, between the bodies, by pads of fibrocartilage
annulus fibrosus
a tough outer covering of intervertebral disks
nucleus pulposus
a soft, pulpy center of intervertebral disks
cervical spine
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.
atlas
The first cervical vertebra (C1). It is a ringlike structure with no vertebral body and a very short spinous process called the posterior tubercle.
axis
The second cervical vertebra (C2). It is the vertebra on which the atlas rotates, allowing the head to turn from side to side.
dens, or odontoid process
Superior to the body of the axis is a toothlike projection
vertebra prominens
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.
thoracic spine
The thoracic spine is sometimes also referred to as the dorsal spine. It consists of 12 vertebrae and has a kyphotic curve.
Intervertebral foramina
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
zygapophyseal joints
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.
lumbar spine
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.
pars interarticularis
The narrow segment of bone between the superior and inferior articular processes
Scottie dog
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.
sacrum
At birth, the sacrum consists of five sacral vertebrae. In the adult, they are fused into a solid bony structure (Fig. 15.19).
sacroiliac (SI) joints
The sacrum articulates with the ilia of the pelvis on either side
alae
The lateral portions of the first sacral segment are winglike structures
coccyx
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.
sacrum and coccyx
Together the sacrum and coccyx form a kyphotic curve. This curvature is more pronounced in females than in males.
sacral base angle
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.
typical cervical vertebrae
The third (C3) through sixth (C6) cervical vertebrae are termed the typical cervical vertebrae
sacral foramina
The four pairs of sacral foramina are passages for nerves.
coccygeal cornua
Two small bony projections extend superiorly from the posterior aspect on each side of the first coccygeal segment.(singular cornu, which means “horn”)
sacral cornua
Two small bony projections from the posterior inferior aspect of the sacrum.
(singular cornu, which means “horn”)
The most common areas for coned-down radiography are
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.
AP projection
Two radiographs are necessary to demonstrate the entire cervical spine in the AP projection.
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.
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.
small focal spot
Detail is also enhanced by the use of the small focal spot.
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.
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.
The routine examination of the cervical spine includes
the AP axial (lower cervical), AP (upper cervical), and lateral projections.
AP Axial Projection (Lower Cervical Spine)
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).
AP Projection/Open Mouth Technique (Upper Cervical Spine)
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.
Cervical Spine - Lateral Projection (Grandy Method)
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.
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.
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).
Oblique Projections
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).
Cervical Spine - Oblique Projection
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).
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.
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.
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.
For this reason, it is desirable to use the anode heel effect
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.
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.
The routine examination of the thoracic spine includes
the AP and lateral projections.
Thoracic Spine - AP Projection
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.
Thoracic Spine - Lateral Projection
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).
The routine examination of the lumbar spine includes
the AP or PA and lateral projections.
Lumbar Spine - AP or PA Projection
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.
Lumbar Spine - Lateral Projection
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).
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.
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).
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.
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).
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.
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).
The routine examination of the SI joints includes
the AP oblique projections. The AP axial projection of the lumbosacral junction and the SI joints may also be included.
Sacroiliac Joints - AP Oblique Projection
Bilateral AP oblique projections are usually taken for comparison.
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.
The routine examination of the sacrum includes
the AP axial and lateral projections.
Sacrum - AP Axial Projection
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).
Sacrum - Lateral Projection
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.
The routine examination of the coccyx includes
the AP axial and lateral projections.
Coccyx - AP Axial Projection
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).
Coccyx - Lateral Projection
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).
Full Spine - PA or AP Projection (Frank et al. Method)
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.
Full Spine - Lateral Projection
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.
sacralization of L5
Sometimes one or both spinous processes of L5 become fused to the sacrum
spina bifida occulta
Usually spina bifida is relatively insignificant and produces no symptoms,
spina bifida vera
Less commonly, the defect may be quite large, leaving the spinal cord unprotected;
pathologic fractures
In bones weakened by disease processes, fractures may occur with little or no trauma.
Pathologic compression fractures of the thoracic spine caused by osteoporosis
are often seen in elderly women (Fig. 15.86).
Spondylosis
refers to fixation or fusion of vertebrae.
Spondylitis
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.
Spondylolysis
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.
Spondylolisthesis
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.
Spondyloschisis
is the term for a congenital fissure (split or cleft) in the neural arch.
degenerative disk disease (DDD)
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.
Disk herniation or herniated nucleus pulposus (HNP)
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.
Disk herniation
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.
disk pathology
Myelography, discography, computed tomography, and magnetic resonance imaging studies (Fig. 15.93) may be used to identify disk pathology.
Sciatica
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.
stenosis
narrowing of the intervertebral foramina
33 vertebrae or spinal segments:
7 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 4 coccygeal.
Most vertebrae consist of
an anterior body, a posterior vertebral arch, two lateral projections called transverse processes, and a posterior projection called the spinous process.
