RAD 3030: Lumbar Spine, Sacrum, and Coccyx

What are the largest individual vertebrae in the vertebral column?

The five lumbar vertebrae.

Why are lumbar vertebrae the strongest in the vertebral column?

Because the load of body weight increases toward the inferior end of the column.

What is a common site for injury in the lumbar region?

The cartilaginous disks between the inferior lumbar vertebrae.

Where are the lumbar vertebrae located in relation to the thoracic vertebrae?

Just inferior to the 12 thoracic vertebrae.

Which lumbar vertebra is the largest?

L5.

What are intervertebral foramina?

Spaces or openings between pedicles when two vertebrae are stacked.

What forms the intervertebral foramen?

The alignment of the superior and inferior vertebral notches of adjacent vertebrae.

What is the angle of the zygapophyseal joints in the lumbar region?

They form an angle open from 45° to 65° to the midsagittal plane.

What is the pars interarticularis?

The portion of each lamina between the superior and inferior articular processes.

What is the shape of the sacrum?

Shovel-shaped, with the apex pointed inferiorly and anteriorly.

How many segments fuse to form the sacrum in adults?

Five segments fuse into a single bone.

What do the alae of the sacrum represent?

Large masses of bone lateral to the first sacral segment.

What is the promontory of the sacrum?

The anterior ridge of the body of the first sacral segment.

What is the function of the sacral foramina?

To transmit nerves and blood vessels.

What joint is formed by the auricular surface of the sacrum and the ilium?

The sacroiliac joint.

What are the sacral horns?

Small tubercles representing the inferior articular processes of the fifth sacral segment.

What is the coccyx?

The most distal portion of the vertebral column, formed by fused coccygeal segments.

What is the apex of the coccyx?

The distal pointed tip of the coccyx.

How does the coccyx typically curve?

Anteriorly, pointing toward the symphysis pubis.

What is the average number of coccygeal segments in adults?

Three to five segments, typically four.

What is the significance of the central ray angle for AP projections of the sacrum?

It must be angled differently due to the dominant convex curve of the sacrum.

What is demonstrated on a lateral radiographic image of the lumbar region?

The intervertebral foramina.

What are the two types of radiographic projections for the lumbar spine?

Anteroposterior (AP) and posteroanterior (PA) projections.

What is the relationship between the transverse processes and vertebral bodies in AP and PA projections?

The spinous processes are superimposed on the vertebral bodies, and the transverse processes protrude laterally.

What is the typical angle of the sacroiliac joint?

Opens obliquely at an angle of 30°.

What is the primary function of the intervertebral foramina?

To allow passage of spinal nerves and blood vessels.

How does the curvature of the coccyx differ between men and women?

The forward curvature is more pronounced in men and less pronounced in women, where it can project into the birth canal.

What is the most common injury associated with the coccyx?

A direct blow to the lower vertebral column while sitting, often resulting from falling backward.

Why are women more likely to experience a coccyx fracture compared to men?

Due to the shape of the female pelvis and the more vertical orientation of the coccyx.

What is the appearance of the lumbar vertebrae in an oblique position?

They can resemble a 'Scottie dog' when viewed at a 45° oblique angle.

What structures correspond to the features of the 'Scottie dog' in lumbar vertebrae?

The head and neck are the pars interarticularis, the ear is the superior articular process, the eye is the pedicle, and the nose is the transverse process.

What are zygapophyseal joints?

Synovial joints between the superior and inferior articular processes that are freely movable.

How are intervertebral joints classified?

They are classified as cartilaginous joints, specifically amphiarthrodial, due to the presence of intervertebral disks.

What types of movements are possible in the vertebral column?

Flexion, extension, lateral flexion, and rotation.

How are intervertebral foramina visualized?

They are visualized on a true lateral projection of the lumbar spine.

What is the purpose of the posterior oblique position in radiography?

It visualizes the downside zygapophyseal joints.

What is the advantage of the anterior oblique position?

It may be more comfortable for the patient and visualizes the upside zygapophyseal joints.

What degree of rotation is typically used for general lumbar region oblique views?

A 45° oblique rotation.

What degree of rotation may be needed for L1 or L2 lumbar vertebrae?

A rotation of up to 50° may be required.

What is crucial for correct positioning of the lumbar spine, sacrum, and coccyx?

Understanding specific topographic landmarks that can be palpated.

Why is close collimation important in radiography of the lumbar spine?

To reduce radiation exposure due to the proximity of the gonads.

What should be done for patients of reproductive age before lumbar spine radiography?

They must be questioned about the possibility of pregnancy.

How should AP projections of the lumbar spine be obtained when the patient is recumbent?

With the knees flexed to reduce lumbar curvature and increase comfort.

What advantage does the PA projection have over the AP projection?

It places the lumbar spine in a position that allows better visualization of intervertebral disk spaces and reduces ovarian radiation dose.

What is a disadvantage of the PA projection in lumbar vertebrae imaging?

It increases the object-image receptor distance (OID), resulting in magnification and reduced image resolution, especially in patients with a large abdomen.

How do higher kVp and lower mAs affect patient doses in imaging?

They reduce patient doses for all imaging systems, with digital systems typically using higher kVp than analog systems.

What is the minimum standard source-to-image distance (SID) for lumbar imaging?

Typically 40 inches, but may be increased to 42, 44, or 48 inches to reduce magnification.

Why is correct part-IR alignment important in lumbar radiography?

It ensures the beam passes through the intervertebral disk spaces, which may require a radiolucent sponge for proper alignment.

What is the purpose of computed tomography (CT) in evaluating the vertebral column?

CT is useful for demonstrating a wide range of pathologic conditions, including fractures, disk disease, and neoplastic disease.

What advantage does magnetic resonance (MR) have over other imaging modalities for the lumbar spine?

MR is superior for evaluating soft tissue structures, such as the spinal cord and intervertebral disk spaces.

What is the function of a radionuclide bone scan in nuclear medicine?

It detects skeletal pathologic processes by using a radiopharmaceutical tracer that highlights areas of increased bone activity.

What conditions can be demonstrated on a bone scan?

Skeletal metastases, inflammatory conditions, Paget disease, neoplastic processes, and osteomyelitis.

What is bone densitometry (BD) used for?

It measures bone mass noninvasively, often assessing the lumbar spine for conditions like osteoporosis.

What are common causes of bone mass loss detected by bone densitometry?

Long-term steroid use, hyperparathyroidism, estrogen deficiency, advancing age, smoking, sedentary lifestyle, and alcoholism.

What is myelography and what does it visualize?

Myelography involves injecting contrast medium into the subarachnoid space to visualize soft tissue structures in the spinal canal.

What is ankylosing spondylitis?

A systemic illness that primarily affects men aged 20 to 40, causing pain and stiffness due to inflammation of spinal joints.

What causes compression fractures in the vertebral column?

They may result from trauma, osteoporosis, or metastatic disease, leading to a wedge-shaped vertebra.

What are Chance fractures and who is at risk?

They result from hyperflexion forces and are common in patients wearing lap-type seat belts during sudden deceleration.

What is a herniated nucleus pulposus (NHP) and its common cause?

Also known as a herniated lumbar disk, it occurs when the inner part of the disk protrudes due to trauma or improper lifting.

What is lordosis?

It describes the normal concave curvature of the lumbar spine, which can become exaggerated due to various factors.

What are the characteristics of metastatic lesions in the vertebrae?

They can be osteolytic (destructive), osteoblastic (proliferative), or a combination, leading to a moth-eaten bone appearance.

What is scoliosis?

A lateral curvature of the vertebral column that often involves rotation of the vertebrae, affecting thoracic and lumbar regions.

What is spina bifida?

A congenital condition where the posterior aspects of the vertebrae fail to develop, exposing part of the spinal cord.

What is spondylolisthesis?

It involves the forward movement of one vertebra relative to another, commonly due to defects or severe osteoarthritis.

What is spondylolysis?

The dissolution of a vertebra, often due to aplasia of the vertebral arch and separation of the pars interarticularis, commonly occurring at L4 or L5.

What anatomy is demonstrated in the AP (or PA) projection of the lumbar spine?

Lumbar vertebral bodies, intervertebral joints, spinous and transverse processes, SI joints, and sacrum.

What is the recommended collimation field size for the AP projection of the lumbar spine?

14 x 17 inches for T11 to the distal sacrum, and 11 x 14 inches for T12 to S1.

What indicates no patient rotation in the AP projection of the lumbar spine?

SI joints equidistant from spinous processes, spinous processes in midline, and equal length of transverse processes.

What anatomy is visualized in the posterior (or anterior) oblique position of the lumbar spine?

Zygapophyseal joints, with RPO and LPO showing downside and RAO and LAO showing upside.

What is the correct patient rotation for the lumbar spine oblique positions?

Accurate 45° rotation indicated by open zygapophyseal joints and the pedicle positioned between the midline and lateral aspect of the vertebral border.

What anatomy is demonstrated in the lateral position of the lumbar spine?

Intervertebral foramina L1-L4, vertebral bodies, intervertebral joints, spinous processes, and L5-S1 junction.

What indicates no rotation in the lateral position of the lumbar spine?

Superimposed greater sciatic notches and posterior vertebral bodies.

What anatomy is demonstrated in the lateral L5-S1 position?

L5 vertebral body, first and second sacral segments, and L5-S1 joint space.

What is the purpose of the AP axial projection of L5-S1?

To demonstrate sacroiliac joints with equal distance from the spine, indicating no pelvic rotation.

What is visualized in the PA projection of the scoliosis series?

Thoracic and lumbar vertebrae, including 1 to 2 inches of the iliac crests.

What indicates no patient rotation in the scoliosis series?

Alignment of thoracic and lumbar vertebrae with spinous processes in the midline and symmetry of the iliac alae/wings.

What is demonstrated in the lateral position (erect) of the scoliosis series?

Thoracic and lumbar vertebrae, including 1 to 2 inches of the iliac crests, with open intervertebral foramina.

What does the Ferguson method in the scoliosis series visualize?

Thoracic and lumbar vertebrae, including 1 to 2 inches of the iliac crests.

What is the purpose of the lateral positions for hyperextension and hyperflexion in spinal fusion series?

To assess the spinal column alignment and open intervertebral joint spaces.

What anatomy is demonstrated in the AP axial projection of the sacrum?

Sacrum, SI joints, and L5-S1 intervertebral joint space.

What indicates correct alignment of the sacrum in the AP axial projection?

Alignment of the medial sagittal crest and coccyx with the symphysis pubis, free of foreshortening.

What is visualized in the AP axial projection of the coccyx?

Coccyx, which should appear free of superimposition and projected superior to the pubis.

What indicates no rotation in the lateral position of the sacrum and coccyx?

Superimposed greater sciatic notches and femoral heads.

What anatomy is demonstrated in the AP axial projection of the sacroiliac joints?

Sacroiliac joints and L5-S1 intervertebral joint space.

What indicates no rotation in the posterior oblique positions of the sacroiliac joints?

No superimposition of the ala of the ilium and sacrum with the open SI joint.