The columna vertebralis (spine) is divided into four regions: the vertebrae cervicales, thoracicae, lumbales, and sacrales. Both the cervical and lumbar spines demonstrate lordosis (inward curvature); the thoracic and sacral spines demonstrate kyphosis (outward curvature).
Spinal development
The characteristic curvatures of the adult spine appear over the course of postnatal development, being only partially present in a newborn. The newborn has a “kyphotic” spinal curvature (A); lumbar lordosis develops later and becomes stable at puberty (C).
Fig. 2.3 Bones of the columna vertebralis
The procc. transversi of the vertebrae lumbales are originally rib rudiments and so are named procc. costales.
Fig. 2.4 Structural elements of a vertebra
Left posterosuperior view. With the exception of the atlas (C1) and axis (C2), all vertebrae consist of the same structural elements.
The seven vertebrae of the cervical spine differ most conspicuously from the common vertebral morphology. They are specialized to bear the weight of the head and allow the neck to move in all directions. C1 and C2 are known as the atlas and axis, respectively. C7 is called the vertebra prominens for its long, palpable proc. spinosus.
Injuries in the cervical spine
The cervical spine is prone to hyperextension injuries, such as “whiplash,” which can occur when the head extends back much farther than it normally would. The most common injuries of the cervical spine are fractures of the dens of the axis, traumatic spondylolisthesis (anterior slippage of a corpus vertebrae), and atlas fractures. Patient prognosis is largely dependent on the spinal level of the injuries (see p. 42).
This patient hit the dashboard of his car while not wearing a seat belt. The resulting hyperextension caused the traumatic spondylolisthesis of C2 (axis) with fracture of the arcus vertebrae of C2, as well as tearing of the ligaments between C2 and C3. This injury is often referred to as “hangman's fracture.”
Osteoporosis
The spine is the structure most affected by degenerative diseases of the skeleton, such as arthrosis and osteoporosis. In osteoporosis, more bone material gets reabsorbed than built up, resulting in a loss of bone mass. Symptoms include compression fractures and resulting back pain.
The os sacrum is formed from five postnatally fused vertebrae sacrales. The basis ossis sacri articulates with the 5th vertebra lumbalis, and the apex ossis sacri articulates with the os coccygis, a series of three or four rudimentary vertebrae. See Fig. 19.1, p. 228.
Fig. 2.16 Discus intervertebralis in the columna vertebralis
Midsagittal section of T11–T12, left lateral view. The disci intervertebrales occupy the spaces between vertebrae (symphyses intervertebrales, see p. 16).
Fig. 2.17 Structure of discus intervertebralis
Anterosuperior view with the anterior half of the disk and the right half of the end plate removed. The discus intervertebralis consists of an external fibrous ring (anulus fibrosus) and a gelatinous core (nucleus pulposus).
Fig. 2.18 Relation of discus intervertebralis to canalis vertebralis
Fourth vertebra lumbalis, superior view.
Disk herniation in the lumbar spine
As the stress resistance of the anulus fibrosus declines with age, the tissue of the nucleus pulposus may protrude through weak spots under loading. If the fibrous ring of the anulus ruptures completely, the herniated material may compress the contents of the foramen intervertebrale (radices nervorum spinalium and blood vessels—see posterolateral herniation below). These patients often suffer from severe local back pain. Pain is also felt in the associated dermatome (see p. 42). When the radix motoria of the n. spinalis is affected, the muscles served by that n. spinalis will show weakening. It is an important diagnostic step to test the muscles innervated by a nerve from a certain spinal segment, as well as the sensitivity in the specific dermatome. Example: The first sacral nerve root innervates the mm. gastrocnemius and soleus; thus, standing or walking on toes can be affected (see p. 440).
Posterior herniation (A, B) In the MRI, a conspicuously herniated disk at the level of L3–L4 protrudes posteriorly (transligamentous herniation). The dural sac is deeply indented at that level. *CSF (cerebrospinal fluid, liquor cerebrospinalis).
Posterolateral herniation (C, D) A posterolateral herniation may compress the n. spinalis as it passes through the foramen intervertebrale. If more medially positioned, the herniation may spare the nerve at that level but impact nerves at inferior levels.
Table 2.2 Joints of the columna vertebralis
Craniovertebral joints |
||
|
Art. atlantooccipitalis |
Occiput–C1 |
|
Artt. atlantoaxiales |
C1–C2 |
Joints of the corpora vertebrarum |
||
|
Uncovertebral joints |
C3–C7 |
|
Symphyses intervertebrales |
C2–S1 |
Joints of the arcus vertebrae |
||
|
Artt. zygapophysiales |
C2–S1 |
Fig. 2.20 Articulationes zygapophysiales (intervertebral facet joints)
The orientation of the artt. zygapophysiales differs between the spinal regions, influencing the degree and direction of movement.
Fig. 2.21 Uncovertebral joints
Anterior view. Uncovertebral joints form during childhood between the unci (procc. uncinati) of C3–C7 and the corpora vertebrarum immediately superior. The joints may result from fissures in the cartilage of the disks that assume an articular character. If the fissures become complete tears, the risk of nucleus pulposus herniation is increased (see p. 15).
Proximity of the nervus spinalis and arteria vertebralis to the uncus
The n. spinalis and a. vertebralis pass through the foramina intervertebrale and transversarium, respectively. Bony outgrowths (osteophytes) on the uncus resulting from uncovertebral arthrosis (degeneration) may compress both the nerve and the artery and can lead to chronic pain in the cervical region.
The artt. atlantooccipitales are the two articulations between the convex condyli occipitales of the os occipitale and the slightly concave facies articulares superiores of the atlas (C1). The artt. atlantoaxiales are the two lateral and one medial articulations between the atlas (C1) and axis (C2).
The ligaments of the columna vertebralis bind the vertebrae and enable the spine to withstand high mechanical loads and shearing stresses and limit the range of motion. The ligaments are subdivided into corpus vertebrae ligaments and arcus vertebrae ligaments.
Ligament |
Location |
|
Corpus vertebrae ligaments |
||
|
Lig. longitudinale anterius |
Along anterior surface of corpus vertebrae |
|
Lig. longitudinale posterius |
Along posterior surface of corpus vertebrae |
Arcus vertebrae ligaments |
||
|
Lig. flavum |
Between laminae |
|
Lig. interspinale |
Between procc. spinosi |
|
Lig. supraspinale |
Along posterior ridge of procc. spinosi |
|
Lig. intertransversarium |
Between procc. transversi |
Lig. nuchae* |
Between protuberantia occipitalis externa and proc. spinosus of C7 |
|
*Corresponds to a lig. supraspinale that is broadened superiorly. |
||
Fig. 2.27 Ligamentum longitudinale posterius
Posterior view with canalis vertebralis opened via laminectomy and medulla spinalis removed. The membrana tectoria is a broadened expansion of the lig. longitudinale posterius.
Fig. 2.29 Ligaments of the columna vertebralis: Thoracolumbar junction
Left lateral view of T11–L3, with T11–T12 sectioned in the midsagittal plane.
Fig. 2.31 Ligamenta flava and intertransversaria
Anterior view of opened canalis vertebralis at level of L2–L5. Removed: corpora vertebrarum L2–L4.
Clinical box 2.1
