What is the angle between the intervertebral foramina and the midsagittal plane in the thoracic spine?

1. Resnick D. Degenerative diseases of the vertebral column. Radiology. 1985;156:3–14. [PubMed] [Google Scholar]

2. Kirkaldy-Willis WH, Wedge JH, Yong-Hing K, Reilly J. Pathology and pathogenesis of lumbar spondylosis and stenosis. Spine. 1978;3:319–328. [PubMed] [Google Scholar]

3. An HS, Glover JM. Lumbar spinal stenosis. Historical perspective, classification and pathoanatomy. Sem Spin Surg. 1994;6:67–77. [Google Scholar]

4. Rauschning W. Normal and pathologic anatomy of the lumbar root canals. Spine. 1987;12:1008–1019. [PubMed] [Google Scholar]

5. Kunogi J, Hasue M. Diagnosis and operative treatment of intraforaminal and extraforaminal nerve root compression. Spine. 1991;16:1312–1320. [PubMed] [Google Scholar]

6. Sato K, Kikuchi S. An anatomic study of foraminal nerve root lesions in the lumbar. Spine. 1993;18:2246–2251. [PubMed] [Google Scholar]

7. Lejeune JP, Hladky JP, Cotten A, Vinchon M, Christiaens JL. Foraminal lumbar disc herniation. Experience with 83 patients Spine. 1994;19:1905–1908. [PubMed] [Google Scholar]

8. Frymoyer JW, Gordon SL. New perspectives on low back pain. Park Ridge, Illinois: American Academy of Orthopaedic Surgeons; 1989. pp. 191–193. [Google Scholar]

9. Gilad I, Nissan M. A study of vertebra and disc geometric relations of the human cervical and lumbar spine. Spine. 1986;11:154–157. [PubMed] [Google Scholar]

10. Kameyama T, Hashizume Y, Ando T, Takahashi A. Morphometry of the normal cadaveric cervical spinal cord. Spine. 1994;19:2077–2081. [PubMed] [Google Scholar]

11. Okada Y, Ikata T, Katoh S, Yamada H. Morphologic analysis of the cervical spinal cord, dural tube, and spinal canal by magnetic resornance imaging in normal adults and patients with cervical spondylotic myelopathy. Spine. 1994;19:2331–2335. [PubMed] [Google Scholar]

12. Panjabi MM, Duranceau J, Goel V, Oxland T, Takata K. Cervical human vertebrae. Quantitative three-dimensional anatomy of the middle and lower regions. Spine. 1991;16:861–869. [PubMed] [Google Scholar]

13. Pech P. Corrective investigation of craniospinal anatomy and pathology with computed tomography, magnetic resonance imaging and cryomicrotomy. Acta Radiol. 1988;372(Suppl):127–148. [PubMed] [Google Scholar]

14. Yenerich DO, Haughton VM. Oblique plane MR imaging of the cervical spine. J Comput Assist Tomogr. 1986;10:823–826. [PubMed] [Google Scholar]

15. Schnebel B, Kingston S, Watkins R, Dillin W. Comparison of MRI to contrast CT in the diagnosis of spinal stenosis. Spine. 1989;14:332–337. [PubMed] [Google Scholar]

16. Modic MT, Masaryk TJ, Ross JS, Mulopulos GP, Bundschuh CV, Bohlman H. Cervical radioculopathy: value of oblique MR imaging. Radiology. 1987;163:227–231. [PubMed] [Google Scholar]

17. Tsurda JS, Norman D, Dillon W, Newton TH, Mills DG. Three-dimensional gradient-recalled MR imaging as a screening tool for the diagnosis of cervical radiculopathy. AJNR Am J Neuroradiol. 1989;10:1263–1271. [PMC free article] [PubMed] [Google Scholar]

18. Yousem DM, Atlas SW, Goldberg HI, Grossman RI. Degenerative narrowing of the cervical spine neural foramina: evaluation with high resolution 3DFT gradient-echo MR imaging. AJNR Am J Neuroradiol. 1991;12:229–236. [PMC free article] [PubMed] [Google Scholar]

19. Ross JS, Ruggieri PM, Glicklich M, Obuchowski N, Dillinger J, Masaryk TJ, Qu Y, Modic MT. 3D MRI of the cervical spine: Low flip angle FISP vs. Gd-DTPA TurboFLASH in degenerative disk disease. J Comput Assist Tomogr. 1997;17:26–33. [PubMed] [Google Scholar]

20. Ebraheim NA, An HS, Xu R, Ahmad M, Yeasting RA. The quantitative anatomy of the cervical nerve root groove and the intervertebral foramen. Spine. 1996;21:1619–1623. [PubMed] [Google Scholar]

21. Macnab I. The traction spur. J Bone Joint Surg. 1971;53-A:663–670. [PubMed] [Google Scholar]

22. Panjabi MM, Takata K, Goel VK. Kinematics of lumbar intervertebral foramen. Spine. 1983;8:348–357. [PubMed] [Google Scholar]

23. Penning L, Wilmink JT. Posture-dependent bilateral compression of L4 or L5 nerve roots in facet hypertrophy: A dynamic CT-myelographic study. Spine. 1987;12:488–500. [PubMed] [Google Scholar]

24. Schönström N, Lindahl S, Willén J, Hansson T. Dynamic changes in the dimensions of the lumbar spinal canal: An experimental study in vitro. J Orthop Res. 1989;7:115–121. [PubMed] [Google Scholar]

25. Yoo JU, Zou D, Edwards WT, Bayley J, Yuan HA. Effect of cervical spine motion on the neuroforaminal dimensions of human cervical spine. Spine. 1992;17:1131–1136. [PubMed] [Google Scholar]

26. Farmer JC, Wisneski RJ. Cervical spine nerve root compression. An analysis of neuroforaminal pressures with varying head and arm positions. Spine. 1994;19:1850–1855. [PubMed] [Google Scholar]

Page 2

Most radiography of the spine may be accomplished successfully in either the upright or the recumbent position. In medical practices and hospitals, radiography of the spine is done in both the recumbent and upright positions. In chiropractic practices, spine radiography is almost always done in the upright position. This chapter provides instruction and illustration for both methods.

The spine (Fig. 15-1) is the central portion of the skeletal system. It provides the supporting framework for the body. It also surrounds and protects the spinal cord. The spine is called the vertebral column because it is made up of many irregularly shaped bones known as vertebrae. The spine is divided into five regions: cervical spine, thoracic spine, lumbar spine, sacrum, and coccyx. The vertebrae are named according to spinal region and are numbered from the top down. For example, the third vertebra from the top of the thoracic region is simply called the third thoracic vertebra, abbreviated T3.

When viewed from the front, the normal spinal column is relatively straight. When seen from the side, however, the spine has four curves (Fig. 15-2). It arches anteriorly and posteriorly to provide a springlike flexibility that absorbs shock as we walk and run. A curvature that is convex (bowing outward) anteriorly is called a lordotic curve, or lordosis. One that is convex posteriorly is called a kyphotic curve, or kyphosis. An abnormal lateral curvature is called scoliosis and results from rotation of a lordotic and/or kyphotic curve (Fig. 15-3).

A typical vertebra is illustrated in Fig. 15-4. The blocklike anterior portion is called the body. It consists of cancellous bone with a thin cortex. Posterior to the body is a ring of bone called the vertebral arch. It is formed by the pedicles, which attach to the body on either side, and by the laminae posteriorly. The hole in the ring is called the vertebral foramen. It is the passage for the spinal cord. The concave superior and inferior surfaces of the pedicles are called vertebral notches. The spaces formed by joining with the vertebral notches above and below are the intervertebral foramina, which allow passage of spinal nerves and blood vessels. Two projections, extending laterally from the junction of the pedicles and lamina, are called the transverse processes. The spinous process projects posteriorly and inferiorly from the junction of the lamina. 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. The zygapophyseal joints are diarthrodial joints of the gliding type. Fig. 15-5 illustrates typical joints of the spine.

The vertebrae are cushioned anteriorly, between the bodies, by pads of fibrocartilage called intervertebral disks (Fig. 15-6). These disks have a tough outer covering, the annulus fibrosus, and a soft, pulpy center called the nucleus pulposus.

The cervical spine is the most superior region of the vertebral column. It supports the head and the structures of the neck. The cervical spine consists of seven vertebrae and has a lordotic curve.

The first two cervical vertebrae differ in form from the others to accommodate the support and rotation of the skull. The first cervical vertebra (C1) is called the atlas (Fig. 15-7). It is a ringlike structure with no vertebral body and a very short spinous process called the posterior tubercle. The atlas consists of two lateral masses connected by an anterior arch and a posterior arch. Each lateral mass has superior and inferior articular processes. The superior articular processes articulate with the base of the skull, and the inferior ones form joints with similar processes on the superior aspect of the second cervical vertebra (C2). The transverse processes project laterally and slightly downward from the lateral masses. On the anterior surface of the anterior arch is a rounded process called the anterior tubercle.

The second cervical vertebra (C2) is called the axis (Fig. 15-8). It is the vertebra on which the atlas rotates, allowing the head to turn from side to side. Superior to the body of the axis is a toothlike projection called the dens, or odontoid process. It projects into the anterior portion of the ring of the atlas and acts as a pivot between the two vertebrae.

The third (C3) through sixth (C6) cervical vertebrae are termed the typical cervical vertebrae (Fig. 15-9). The articular processes extend superiorly and inferiorly from a point posterior to the transverse process at the junction of the pedicle and the lamina. Together the articular processes form a column of bone called the articular pillar. The cervical spinous processes are bifid, that is, they are split into two posterior projections, forming a shape somewhat like a fish tail. 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. It is a convenient reference point for the location of other vertebrae.

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 (Fig. 15-10). The C1-C2 articulations differ in position and direction and are best seen in the anteroposterior (AP) projection.

The intervertebral foramina of the cervical spine are oriented anteriorly at an angle of 45 degrees to the sagittal plane. These foramina are also oriented inferiorly at an angle of 15 degrees to the horizontal plane (Fig. 15-11). Nerves branching off the spinal cord exit the vertebral column through these foramina to all parts of the body.

Each cervical transverse process (including those of C1 and C2) features a hole called the transverse foramen (see Fig. 15-9). The transverse foramina form passages on each side for the vertebral artery and vein.

At birth, the sacrum consists of five sacral vertebrae. In the adult, they are fused into a solid bony structure (Fig. 15-19). The sacrum articulates with the ilia of the pelvis on either side, forming the sacroiliac joints. Its broad, flat superior surface is called the sacral base. The lateral portions of the first sacral segment are winglike structures called the alae. The four pairs of sacral foramina are passages for nerves.

The coccyx, the most inferior portion of the spine, is approximately the size of the fifth finger. 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. Two small bony projections extend superiorly from the posterior aspect on each side of the first coccygeal segment. These are called the coccygeal cornua (singular cornu, which means “horn”). They are joined to similar projections from the posterior inferior aspect of the sacrum, called the sacral cornua.

Together the sacrum and coccyx form a kyphotic curve. This curvature is more pronounced in females than in males. The sacral base slopes downward anteriorly, and the degree of slope is called the sacral base angle. This angle is greatest in females. It is greater when standing than when recumbent and is least when supine with the knees flexed. Average sacral base angles for males and females are listed in Table 15-1.

TABLE 15-1

Average Sacral Base Angulation

Body Position	Sacral Base Angle in Males	Sacral Base Angle in Females
Standing	35 degrees	40 degrees
Supine with legs extended	30 degrees	35 degrees
Supine with knees fixed	25 degrees	30 degrees

Many landmarks are used in positioning and alignment for various aspects of spine radiography. Fig. 15-20 illustrates the landmarks of the cranium and face that are helpful for radiography of the cervical spine. Fig. 15-21 shows the topographic anatomy that corresponds to specific vertebral levels of the spine. Memorizing these locations will enhance your ability to position patients accurately.

“Coned-down” radiographs, historically called spot films, may be requested for better visualization of specific areas of the spine. As discussed in Chapter 9, the use of a small radiation field, centered on the area of clinical interest, improves contrast while minimizing the negative effects of distortion and parallax. 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. When taking a closely collimated image of a vertebra that does not have a precise palpable landmark, it is helpful to have reference from routine radiographs. The limited operator can measure the distance from a palpable landmark to the vertebra of clinical interest on the radiograph and use this information to center properly.

Two films 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.

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.

Before undergoing cervical spine radiography, the patient must remove eyeglasses, earrings, hairpins, necklaces, and any clothing that has fasteners that might fall within the radiation field. Dentures and hearing aids should also be removed.

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)

IR:

8 × 10 inches (18 × 24 cm) lengthwise

Body position:

Seated, standing, or supine.

Patient instruction:

Stop breathing. Do not move.

AP Projection/Open Mouth Technique (Upper Cervical Spine)

IR:

8 × 10 inches (18 × 24 cm) lengthwise

Body position: