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chapter 9 lumbar anatomy

Anthony Torres English 42 cards

Cards in this deck (42)

1Lumbar Vertebrae-The largest individual vertebrae are the five lumbar vertebrae.
-These vertebrae are the strongest in the vertebral column because the load of body weight increases toward the inferior end of the column.
-For this reason, the cartilaginous disks between the inferior lumbar vertebrae are common sites for injury and pathologic processes.
2Lateral Perspectives-The transverse processes are fairly small, whereas the posteriorly projecting spinous process is bulky and blunt.
- The palpable lower tip of each lumbar spinous process lies at the level of the intervertebral disk space inferior to each vertebral body.
3figure 9-1 lumbar vertebral lateral view
4Intervertebral Foramina-Intervertebral foramina are spaces or openings between pedicles when two vertebrae are stacked on each other.
5Superior and inferior vertebral notch-Along the upper surface of each pedicle is a half-moon-shaped area called the superior vertebral notch and along the lower surface of each pedicle is another -half-moonshaped area called the inferior vertebral notch.
-When vertebrae are stacked, the superior and inferior vertebral notches line up, and the two half-moon-shaped areas form a single opening, the intervertebral foramina
6lumbar vertebra superior view
7Superior and inferior vertebral notch Continued-Therefore, between every two vertebrae are two intervertebral foramina, one on each side, through which important spinal nerves and blood vessels pass.
-The intervertebral foramina in the lumbar region are demonstrated best on a lateral radiographic image.
8Zygapophyseal Joints- Each typical vertebra has four articular processes that project from the area of the junction of the pedicles and laminae. -The processes that project upward are called the superior articular processes and the processes that project downward are the inferior articular processes.
9Zygapophyseal Joint Continued-The term facet sometimes is used interchangeably with the term zygapophyseal joint; the facet is actually only the articulating surface instead of the entire superior or inferior articular process.
-Fig. 9-1 shows the relative positions of the superior and inferior lumbar articular processes from the lateral perspective.
10Zygapophyseal Joint Continued-The zygapophyseal joints form an angle open from 30° to 50° to the midsagittal plane, as shown in Fig. 9-2.
-The upper or proximal lumbar vertebrae are nearer the 50° angle and the lower or distal lumbar vertebrae are nearer 30°.
-Radiographic demonstration of the zygapophyseal joints is achieved by rotating the patient's body an average of 45°.
11Laminae-The laminae form a bridge between the transverse processes, lateral masses, and spinous process (Fig. 9-2).
-The portion of each lamina between the superior and inferior articular processes is the pars interarticularis.
-The pars interarticularis is demonstrated radiographically on the oblique lumbar image.
12fig 9-2 lumbar vertebra super view
13Lumbar vertebra Posterior View
14Lumbar vertebra Anterior View
15Lateral Lumbosacral Spine...
16spine in the lateral position (Fig. 9-13) shows the following: (A. Body of L1) (B.Body of L3) (C.Intervertebral disk space between L4 and L5) (D.Body of L5) (E.Superimposed intervertebral foramina between L1 and L2)
17Oblique Lumbar Vertebrae (Appearance OF "Scottie Dog"A good 45° oblique projects the various structures in such a way that a "Scottie dog" seems to appear. Fig. 9-15 shows the various components of the Scottie dog.
18scottie dog
19Oblique Lumbar Vertebrae (Appearance OF "Scottie Dog" Continued-The head and neck of the dog are probably the easiest features to recognize.
-The neck is one pars interarticularis (part of the lamina that primarily makes up the shoulder region of the dog).
-The ear of the dog is one superior articular process, whereas the eye is formed by one pedicle.
-One transverse process forms the nose. The front legs are formed by one inferior articular process.
20Dog" A.Nose of the Scottie dog, formed by one transverse process B. Eye, one pedicle seen on end C.Neck of the dog, which is the pars interarticularis D. Front leg of the dog, formed by one inferior articular process E.Pointed ear, one of the superior articular processes F.Zygapophyseal joint, formed by front leg of the Scottie above and ear of the Scottie below Each of the five lumbar vertebrae should assume a similar Scottie dog appearance, with zygapophyseal joint spaces open on a correctly rotated lumbar radiograph.
21Classification of Joints: Zygapophyseal (Apophyseal) Joints-The zygapophyseal joints between the superior and inferior articular processes are classified as synovial joints.
-These joints are lined with synovial membrane. They are diarthrodial, or freely movable, with a plane (gliding) type of movement.
22Intervertebral Joints-The intervertebral joints between the bodies of any two vertebrae contain intervertebral disks that are made up of fibrocartilage and are only slightly movable.
-These joints, which are tightly bound by cartilage, thus are classified as cartilaginous joints.
-They are amphiarthrodial (slightly movable) joints of the symphysis sub- class
23Posterior Oblique-As the drawing and photographs of the skeleton demonstrate, the downside joints are visualized on posterior obliques.
-The downside zygapophyseal joints are not visible on the skeleton because they are "under" the bodies of the vertebrae (Fig. 9-17), but as seen on the inferosuperior sectional drawing, the downside joints would be demonstrated on a posterior oblique.
24Anterior Oblique-The anterior oblique position may be more comfortable for the patient and may allow the natural lumbar curvature of the spine to coincide with the divergence of the x-ray beam.
-because of the pain of weight bearing in the supine position, the patient may be better able to maintain the anterior oblique position with less discomfort and motion.
25Anterior Oblique Continued-As demonstrated, an anterior oblique visualizes the upside joints.
-Therefore, a right anterior oblique (RAO) visualizes the upside, or left, zygapophyseal joints (Figs. 9-20 and 9-22).
- The degree of rotation depends on which area of the lumbar spine is of specific interest.
- A 45° oblique is used for the general lumbar region, but if interest is specifically focused on L1 or L2, the degree of rotation may be increased to 50°.
26Anterior Oblique Continue-If interest is in the L5-S1 area, rotation may be decreased to 30° from an AP or PA projection.
-Some variance is seen among patients but in general, the upper lumbar region requires more degrees of rotation than the lower regions.
-The reason is that the upper lumbar vertebrae take on some shape characteristics of the thoracic vertebrae, which require 70° of rotation to demonstrate the zygapophyseal joints, as described in Chapter 8."
27summary of L spine joint and foramina positioning
28Summary of Joint Classifications of L Spine
29Topographic Landmarks-A. Level a corresponds to the superior margin of the symphysis pubis. The prominence of the greater trochanter is at about the same level as the superior border of the symphysis pubis.
B. The anterior superior iliac supine (ASIS) is approximately the same level (B) as the first or second sacral segment.
C. Level c is the most superior portion of the iliac crest and is at approximately the same level as the junction of the fourth and fifth lumbar vertebrae.
D. The lowest margin of the ribs or lower costal margin (D) is at the approximate level of L2 to L3.
E. The xiphoid tip is approximately at the level of T9-T10."
30Topographic Landmarks
31Patient Position/AP lumbar-AP projections of the lumbar spine are obtained with the knees flexed.
-Flexing the knees (Fig. 9-26) reduces the lumbar curvature (lordosis), bringing the back closer to the radiographic examination table and the lumbar vertebral column more parallel to the image receptor (IR). also, flexing the knees allows for greater patient comfort.
32PA versus AP Projections-the PA projection offers an advantage. -The prone position places the lumbar spine with its natural lumbar curvature in such a way that the intervertebral disk spaces are almost parallel to the diver- gent x-ray beam.
-This position opens up and provides better visualization of the margins of the intervertebral disk spaces.
33PA versus AP Projections Continued- Another advantage of the PA projection in females is a lower ovarian dose, 25% to 30% less for a PA projection compared with an AP.
-However, a disadvantage of the PA projection is the increased object image receptor distance (OID) of the lumbar vertebrae, which results in magnification unsharpness, especially for a patient with a large abdomen.
34PATHOLOGIC FEAUTURES/Compression fractures-compression fractures may be due to trauma, osteoporosis, or metastatic disease.
-The superior and inferior surfaces of the vertebral body are driven together, producing a wedge-shaped vertebra.
-For patients with osteoporosis or other vertebral pathologic processes, the force needed to cause this fracture type may be minor (e.g., lifting light objects).
-This type of fracture rarely causes a neurologic deficit.
35Chance fractures-chance fractures result from a hyperflexion force that causes fracture through the vertebral body and posterior elements (e.g., spinous process, pedicles, facets, transverse processes).
-Patients wearing lap-type seat belts are at risk because these belts act as a fulcrum during sudden deceleration.
36Herniated nucleus pulposus (HNP)-also commonly known as a herniated lumbar disk (slipped disk), is usually due to trauma or improper lifting.
-The soft inner part of the intervertebral disk (nucleus pulposus) protrudes through the fibrous outer layer, pressing on the spinal cord or nerves.
-It occurs most frequently at the L4-L5 levels, causing sciatica (an irritation of the sciatic nerve that passes down the posterior leg).
- Plain radiographs do not demonstrate this condition but can be used to rule out other pathologic processes, such as neoplasia and spondylolisthesis. Myelography once was indicated to visualize this pathologic process. CT and MRI are now the modalities of choice.
37Lordosis-Lordosis describes the normal concave curvature of the lumbar spine and an abnormal or exaggerated concave lumbar curvature.
-This condition may result from pregnancy, obesity, poor posture, rickets, or tuberculosis of the spine.
-A lateral projection of the spine will best demonstrate the extent of lordosis.
38Metatases-metastases are primary malignant neoplasms that spread to distant sites via blood and lymphatics.
-The vertebrae are common sites of metastatic lesions, which may be characterized and visualized on the image as follows:
osteolytic—destructive lesions with irregular margins, osteoblastic—proliferative bony lesions of increased density combination osteolytic and osteoblastic—moth-eaten appearance of bone resulting from the mix of destructive and blastic lesions
39Scoliosis-Scoliosis is lateral curvature of the vertebral column that usually occurs with some rotation of the vertebra.
- It involves the thoracic and lumbar regions.
40Spina bifida-Spina bifida is a congenital condition in which the posterior aspects of the vertebrae fail to develop, thus exposing part of the spinal cord.
-This condition varies greatly in severity and occurs most often at L5
41Spondylolisthesis-Spondylolisthesis involves the forward movement of one vertebra in relation to another.
- It is commonly due to a developmental defect in the pars interarticularis or may result from spondylolysis or severe osteoarthritis.
-It is most common at L5-S1 but also occurs at L4-L5. Severe cases require a spinal fusion.
42Spondylolysis-Spondylolysis is the dissolution of a vertebra, such as from aplasia (lack of development) of the vertebral arch and separation of the pars interarticularis of the vertebra.
-On the oblique projection, the neck of the Scottie dog appears broken. It is most common at L4 or L5.