SPINE: General Principals Flashcards
- The attachments of the ligamentum flavum are best described as:
a. The body of the axis to the sacrum binding the anterior aspect of the vertebral bodies and intervertebral discs together
b. Extending from the axis to the sacrum
c. The ventral aspect of the superior lamina and the dorsal aspect of the inferior lamina
d. The spinous processes ofadjacent vertebrae
e. Dorsal to the spinous process and in continuity with the ligamentum nuchae
c. The ventral aspect of the superior lamina and the dorsal aspect of the inferior lamina
Which one of the following statements is most accurate regarding the C1 vertebra?
a. Possesses a groove for the vertebral artery on its anterior-superior aspect
b. It is weakest where the anterior and posterior arches connect to the lateral masses
c. Load bearing occurs through the anterior tubercle
d. Vertebral artery passes through C1 foramen transversarium
e. Possesses concave superior facets and convex inferior facets
b. It is weakest where the anterior and posterior arches connect to the lateral masses
The ring-like atlas (C1) is unique because during development its body fuses with the axis (C2) to form the odontoid process. Thus, it is composed of two thick, load-bearing lateral masses, with concave superior and inferior articular facets. There is a short anterior arch with a tubercle and articular facet on its posterior aspect for articulation with the dens (odontoid process). The posterior arch is longer and curved, and has a grove on its posterior-superior surface for the vertebral artery. The transverse process of the atlas has a single tubercle, which protrudes laterally and can be palpated in the space between the tip of the mastoid process and the ramus of the mandible. It is weakest at the junction of the anterior and posterior arches with the lateral masses explaining the nature of Jefferson (burst) fracture of C1.
Which one of the following statements is most accurate regarding the C2 vertebra (axis)?
a. Atlantodens interval is normally <11 mm in children
b. Superior articular facet is located posterolaterally to the spinal canal
c. Inferior articular facet is located anterolaterally to the spinal canal
d. Atlantodens interval is normally >3mm in adults
e. Pars interarticularis may fracture in hyperflexion or hyperextension
e. Pars interarticularis may fracture in hyperflexion or hyperextension
catchmint.xyzThe axis (C2) receives its name from its odontoid process (dens), which forms the axis of rotation in the atlantoaxial joint. The dens has an anterior hyaline articular surface for the anterior arch of C1, and a posterior articular surface articulates for the transverse ligament. Relative to the spinal canal, the superior articular processes are located anterolaterally while the inferior articular processes are located posterolaterally—they are connected by the pars interarticularis. Hyperflexion or hyperextension injuries may subject C2 to shear stresses, resulting in a fracture through the pars region (hangman’s fracture). The C2 pedicle is a narrow area between the vertebral body and the pars. The atlantodens interval (ADI) is the space between the hyaline cartilage surfaces of the anterior tubercle of the C1 and the anterior dens; it is <3 mm adults and 5 mm children.
Which one of the following best describes the uncovertebral (Lushka’s) joints in subaxial cervical spine?
a. Between superior and inferior articular facets
b. Between vertebra below and inferolateral uncinate processes of the vertebra above
c. Between vertebra above and the superolateral uncinate processes of the vertebral body below
d. Between transverse processes of adjacent vertebrae
e. Between spinous processes of adjacent
vertebrae
c. Between vertebra above and the superolateral uncinate processes of the vertebral body below
Typical cervical vertebra (C3-C6) have an anterior body and a posterior arch formed by lamina and pedicles. The lamina blends into the lateral masses, which comprises the bony region between the superior and inferior articular facets/processes. The uncovertebral (Lushka’s) joints are formed by uncinate processes that extend upward from the lateral margin of the superior surface of the vertebral body and limit lateral flexion/guide flexionextension. Spinal nerves exit via the intervertebral foramina formed between adjacent pedicles, facet joint and posterior aspect of the vertebral body. The transverse processes of the lower cervical spine are directed anterolaterally and composed of an anterior costal element and a posterior transverse element. The transverse foramen, located at the base of the transverse process, permits passage of the vertebral artery. The spinous process originates in the midsagittal plane at the junction of the lamina and is bifid between C2 and C6.
Which one of the following is NOT a unique anatomic feature of the C7 vertebra?
a. Inferior articular process of C7 is oriented in a relatively perpendicular direction
b. It has the thinnest lateral mass in the cervical spine
c. Its transverse process only possesses a pos- terior tubercle
d. Its foramen transversarium is the entry point for the vertebral artery
e. It has a long, non-bifid spinous process
d. Its foramen transversarium is the entry point for the vertebral artery
The unique anatomic features of the C7 vertebra
reflect its location as the transitional vertebra at
the cervicothoracic junction:
* Long non-bifid spinous process
* Its foramen transversarium usually contains vertebral veins only (vertebral artery enters at the C6 level)
* The C7 transverse process is large in size and possesses only a posterior tubercle
* The C7 lateral mass is the thinnest lateral mass in the cervical spine
* The inferior articular process of C7 is oriented in a relatively perpendicular direction (like a thoracic facet joint)
Orientation of facet joint planes in the subaxial cervical spine are which one of the following?
a. 75° in the sagittal plane and 30° in the coronal plane
b. 60° in the sagittal plane and 15° in the coronal plane
c. 45° in the sagittal plane and 0° in the coronal plane
d. 30° in the sagittal plane and 15° in the coronal plane
e. 15° in the sagittal plane and 30° in the coronal plane
c. 45° in the sagittal plane and 0° in the coronal plane
The orientation of the facet joints is a major factor in the range of motion of the cervical spine. Approximately 50% of cervical flexion-extension occurs at the occiput-C1 level. Approximately 50% of cervical rotation occurs at the C1-C2 level. Lesser amounts of flexion-extension, rotation, and lateral bending occur segmentally between C2 and C7 where facet joints are oriented 45° in the sagittal plane and 0° in the coronal plane. These are the most horizontally oriented regional facet joints in the spinal column. The orientation of these facets allows flexion-extension (greatest at the C5-C6 and C6-C7), lateral flexion, and rota- tion of the lower cervical spine. Laxity of the joint capsule permits sliding motion to occur and explains why unilateral or bilateral dislocation without fracture may occur.
Which one of the following best describes the constituents of the intervertebral disc?
a. Annulus fibrosus type I collagen, nucleus pulposus type IV collagen
b. Annulus fibrosus type I collagen, nucleus pulposus type II collagen
c. Annulus fibrosus type II collagen, nucleus pulposus type II collagen
d. Annulus fibrosus type IV collagen, nucleus pulposus type II collagen
e. Annulus fibrosus type IV collagen, nucleus pulposus type III collagen
b. Annulus fibrosus type I collagen, nucleus pulposus type II collagen
Each intervertebral disc is composed of a central gel-like nucleus pulposus surrounded by a peripheral fibrocartilaginous annulus fibrosus. The annulus fibrosus (type I collagen) attaches to the cartilaginous endplates via collagen fibers, which run obliquely at a 30° angle to the surface of the vertebral body and in a direction opposite to the annular fibers of the adjacent layer. The nucleus pulposus (glycosaminoglycans and type II collagen) can bind large amounts of water. In a normal healthy disc, loads acting on the disc are transferred to the annulus by intradiscal pressure generated by the nucleus. With aging, then nucleus binds less water and becomes dehydrated resulting in increased loading of the annulus. Fissuring and disruption of the annulus predisposes to herniation of nuclear material through it.
Site of entry for thoracic pedicle screw is best described as which one of the following?
a. Where the facet joint and transverse process intersect
b. Where the pars interarticularis and lamina intersect
c. Where the superior facet and lamina intersect
d. Where the inferior facet and lamina intersect
e. Where the transverse process and lamina intersect
a. Where the facet joint and transverse process intersect
The paired pedicles arise from the posteriorsuperior aspect of the vertebral bodies. The superior-inferior pedicle diameter is consistently larger than the medial-lateral pedicle diameter. Pedicle widths are narrowest at the T4-T6 levels, with medial-lateral pedicle diameter increasing both above (T1-T3) and below this region. The medial pedicle wall is two to three times thicker than the lateral pedicle wall across all levels of the thoracic spine. The medial angulation of the pedicle axis decreases from T1 to T12. The site for entry into the thoracic pedicle from a posterior spinal approach is in the region where the facet joint and transverse process intersect and varies slightly, depending on the specific thoracic level.
Which one of the following best describes Batson’s plexus?
a. System of valveless veins located within the vertebral canal and body
b. Sympathetic plexus located along the anterior prevertebral tissues in the region of L5 vertebral body and L5/S1 disc
c. Paired segmental arteries from L1 to L4 vertebrae arising from the aorta
d. Parasympathetic plexus located along the anterior prevertebral tissues in the region of L4 vertebral body and L3/L4 disc
e. Nervous supply to the bladder
a. System of valveless veins located within the vertebral canal and body
Batson’s plexus is a system of valveless veins located within the spinal canal and around the vertebral body. It is an alternate route for venous drainage to the inferior vena cava system. Because it is a valveless system, any increase in abdominal pressure (e.g. prone positioning) can cause blood to flow preferentially toward the spinal canal and surrounding bony structures. Batson’s plexus also serves as a preferential pathway for metastatic tumor and infection spread to the lumbar spine.
Vertebral artery V2 segment is best described as which one of the following?
a. Runs from transverse foramen of C6 to
transverse foramen of C2
b. Curves around the C1 lateral mass
c. Runs from transverse foramen of C2 to
the dura
d. Ascends anterior to the roots of the
hypoglossal nerve
e. Runs from the posterior atlanto-occipital membrane to the origin of PICA
a. Runs from transverse foramen of C6 to
transverse foramen of C2
The vertebral artery is the first branch off the subclavian artery and provides the major blood supply to the cervical spinal cord, nerve roots, and vertebrae. It can be divided into four segments
Panjabi & White’s definition of spinal stability is most accurately described by which one of the following?
a. The loss of the ability of the spine under physiological loads to maintain relationships between vertebrae to prevent pain or deformity
b. The loss of the ability of the spine under physiological loads to maintain relationships between vertebrae to prevent pain
c. The loss of the ability of the spine under physiological loads to maintain relationships between vertebrae to prevent pain, deformity or neurological injury
d. The loss of the ability of the spine under physiological loads to maintain relationships between vertebrae to prevent neurological injury
e. The loss of the ability of the spine under physiological loads to maintain relationships between vertebrae to prevent pain or neurological injury
c. The loss of the ability of the spine under physiological loads to maintain relationships between vertebrae to prevent pain, deformity or neurological injury
The loss of the ability ofStabilization of the spine can be provided by spinal implants in the short-term, but long-term stabilization occurs only if vertebral bony fusion is successful. Non-fusion will ultimately result in spinal implant failure. The surgical factors include fusion technique, appropriate location (anterior, posterior, or combined anterior and posterior column fusion), and use of appropriate spinal implants to adequately support the spine during bony fusion. Spinal implants: 1. Immobilize spinal segments during the fusion process to increase the rate of successful arthrodesis 2. Restore spinal stability lost due to pathologic processes (e.g. tumor, infection, fracture) 3. Correct spinal deformities (e.g. scoliosis, kyphosis, spondylolisthesis) 4. Maintain stability/prevent post-surgical spinal deformity when extensive decompression of the neural elements is required (e.g. spinal stenosis). FURTHER READING White AA, Panjabi MM. Clinical biomechanics of spine. Abnormal flexion-extension mobility—Paradoxical motion. Kinematics of Spine Chap. 2; 89., Philadelphia, JB Lippincott, 1990. the spine under physiological loads to maintain relationships between vertebrae to prevent pain, deformity or neurological injury.
Load-sharing concept of spinal biomechanics holds that in the normal lumbar spine:
a. Approximately 80% of axial load is carried by the anterior spinal column and the remaining 20% is transmitted through the posterior spinal column
b. Approximately 70% of axial load is carried by the anterior spinal column and the remaining 30% is transmitted through the posterior spinal column
c. Approximately 60% of axial load is carried by the anterior spinal column and the remaining 40% is transmitted through the posterior spinal column
d. Approximately 50% of axial load is carried by the anterior spinal column and the remaining 50% is transmitted through the posterior spinal column
e. Approximately 40% of axial load is carried by the anterior spinal column and the remaining 60% is transmitted through the posterior spinal column
a. Approximately 80% of axial load is carried by the anterior spinal column and the remaining 20% is transmitted through the posterior spinal column
This 80/20 relationship between anterior and posterior columns is termed the load-sharing concept, and it becomes clear that any anterior column incompetence would require the entire axial load to pass through the posterior column (exceeding the strength of any posterior spinal implant). In this situation, posterior spinal implants will fail by fatigue, permanent deformation, or implant migra- tion through bone if used alone—hence it is critical to assess the need to reconstruct an incompetent anterior spinal column.
Placement of lumbar pedicle screws at L3 and L4 level should use which one of the following entry point?
a.The site where the transverse process joins the superior articular process just lateral to the pars interarticularis
b. The site where the lamina joins the superior articular process just lateral to the pars interarticularis
c. The site where the transverse process joins the inferior articular process just lateral to the pars interarticularis
d. The site where the lamina joins the inferior articular process just lateral to the pars interarticularis
e. The pars interarticularis
a.The site where the transverse process joins the superior articular process just lateral to the pars interarticularis
In the lumbar region, the entry site for screw placement is located at the upslope where the transverse process joins the superior articular process just lat- eral to the pars interarticularis. This site can be approximated by making a line along the midpoint of the transverse process and a second line along the lateral border of the superior articular process. The crossing point of these two lines defines the entry site to the pedicle. Advantages of pedicle screws include secure fixation, the ability to apply forces to both the anterior and posterior columns of the spine from a posterior approach, and the capability to achieve fixation when lamina are deficient. The disadvantages of pedicle screws include technical challenges related to screw placement and the potential for neurologic, vascular, and visceral injury due to misplaced screws. Pedicle screws may be: fixed head (monoaxial), mobile head (polyaxial), or bolts (require a separate connector for attachment to the longitudinal member).
Which one of the following is most accurate regarding placement of thoracic pedicle screws?
a. Varies widely depending on level
b. Straight-head screw trajectory is parallel to the facet joint
C. Anatomic screw trajectory is along the long axis of the pedicle
d. Entry point is where the transverse process joins the superior articular process just medial to the pars interarticularis
e. The pars interarticularis is the LEAST useful landmark
C. Anatomic screw trajectory is along the long axis of the pedicle
In the thoracic region, screw placement is initiated at the lateral aspect of the pedicle. The pedicle entry site is determined by referencing the transverse process, the superior articular process, and the pars interarticularis. Exact position of the entry site is adjusted depending on the specific level of the thoracic spine and whether the screw trajectory is straight-ahead (perpendicular to vertebral body) or anatomic (along true axis of pedicle; angulated relative to vertebral body).
The primary goal of dynamic stabilization techniques in the spine is best described as which one of the following?
a. Produce less stress on adjacent vertebral segments
b. Reduce implant failure
c. Reduce motion between segments compared to currently available constructs
d. Increase the rate of spinal arthrodesis
e. Avoid the need for pedicle screw placement
a. Produce less stress on adjacent vertebral segments
Dynamic stabilization is a concept of placing anchors (generally pedicle screws) into the spine and connecting these anchors with a flexible longitudinal member (e.g. rod, cable, spring). The goal of this type of implant is to constrain but not eliminate motion. Proponents of this concept believe this type of implant will produce less stress on the adjacent spinal segments and may prevent some of the complications observed following spinal fusion (e.g. adjacent-level degenerative changes). Opponents worry that without concurrent spinal arthrodesis, these implants may loosen or fail prematurely and require revision surgery. Currently, there are limited data to prove or disprove the scientific utility of this concept.
The spinal construct shown below would most likely have been used for which one of the following
a. Basilar invagination in rheumatoid arthritis
b. C3 vertebral body metastasis
c. Hangman fracture
d. Jefferson fracture
e. Type II odontoid peg fracture
a. Basilar invagination in rheumatoid arthritis
