Vertebral Fractures

Published on 16/04/2015 by admin

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Last modified 22/04/2025

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3 Vertebral Fractures

Anatomy of the Vertebral Column

image

Vertebral Column and Spine

Articulated Vertebrae and Spine

• Number: 31 = C7 + T12 + L5 + S5 + Co4
• Primary curvatures: thoracic, sacral; present in utero
• Secondary curvatures: cervical, lumbar; develop postnatally
• Curvatures dependent on body shapes and sizes and disc shapes and sizes
• Consequences of upright gait, large head, high-speed travel: major fracture forces typically are on cervical or lumbar vertebrae
• Physical landmarks for surgery

image C2-C3 disc: level of mandible
image C3 body: level of hyoid bone
image C4-C5 bodies: level of thyroid cartilage
image C7 spine: vertebra prominens
image T7 body: level of inferior angle of scapula
image L4-L5 disc: level of iliac crest

Typical Vertebrae

• Parts and landmarks: body, pedicles, lamina(e), spine, transverse processes, superior articular facets, inferior articular facets
• Associated rib components (variable): developmental (homeobox) anomalies can produce cervical and lumbar ribs.

Cervical Vertebrae

• C1, atlas

image No body, thin anterior and posterior arches, posterior tubercle, no laminae or spine
image Lateral masses with superior (atlantooccipital) and interior (atlantoaxial) articular facets
image No transverse foramina grooves for vertebral arteries entering foramen magnum

• C2, axis

image Body includes dens or odontoid process representing developmental C1 body.
image Broad lamina with bifid posterior process
image Large interarticular part with planar superior articular facet for C1, more typical inferior articular process for C3
image Strongest cervical vertebra

• Foramina transversaria

image Contain vertebral arteries from C6 through C2
image Anterior rims are rib components.

• C3-C7, typical cervical vertebrae

image Large, upward-cupped bodies
image Bifid spinous processes
image C6 and C7 spines are longest of the cervical vertebrae.
image Superior and inferior articular facets constrain flexion, extension, and lateral flexion.

Thoracic Vertebrae

• “Typical” vertebrae
• Synovial hemifacets on upper and lower body for heads of ribs; vertebral-costal joints
• Synovial facets on transverse processes for costotransverse joints with tubercles of ribs
image

Lumbar Vertebrae and Intervertebral Disc

Lumbar Vertebrae

• Largest bodies of all regional vertebrae, bear weight of body above
• Spinal foramina are larger superiorly, and spinal roots are larger inferiorly: L5 spinal nerves fit tightest.

Sacral Vertebrae

• Fusion of sacral bodies typically occurs in adulthood, though disc remnants can remain visible on imaging.
• Parts and landmarks

image Ala
image Sacroiliac articular surfaces
image Lumbosacral articular (disc) surface
image Promontory
image Fused bodies (5)
image Anterior and posterior foramina
image Coccyx (~4 segments)

• Sacral canal

image Continuation of vertebral canal
image Contains meninges and roots of cauda equina

• Posterior

image Median and lateral sacral crests
image Superior articular facet (to L5 inferior facet)
image Sacral hiatus (end of sacral canal, ref. caudal anesthesia)

• Posterior and anterior sacrococcygeal ligaments are the tail ligaments.
• See Pelvic Fractures for more information.

Joints and Ligaments of the Spine

• Vertebral body joints: discs, symphyses

image Anulus fibrosus: dense regular CT
image Nucleus pulposus: gelid remnant of embryonic notocord
image Anulus reinforced anteriorly by broad anterior longitudinal ligament: resists hyperextension
image Anulus weakest lateral to narrow dorsal longitudinal ligament, favors herniation posteriorly near intervertebral foramina and exiting spinal roots
image Discs support range of movement between adjoining vertebrae (dashpot function).

• Vertebral arch joints: between superior and inferior articular processes of successive vertebrae

image Synovial, zygapophyseal, sliding
image Shape of articular processes determines axes of movement between regional vertebrae.

• Ligamenta flava run between laminae.
• Interspinous and supraspinous ligaments

image Prevent hyperflexion, help maintain upright extension of neck and lower back
image Continuous with raphes of trapezius, lumbar aponeuroses

• Ligamentum nuchae: supraspinous ligament + raphes of trapezius and cervical muscles
• Tectorial membrane

image Epidural
image Continuous with posterior longitudinal ligament
image Stabilizes atlantooccipital joints

• Cruciate ligament (craniovertebral)

image Deep to tectorial membrane
image Part of synovial atlantoaxial joint
image Transverse + longitudinal parts
image Transverse ligaments pass posterior to dens and attach to inner anterior arch of atlas.
image Superior longitudinal band attaches to occipital bone above foramen magnum.
image Inferior longitudinal band attaches to C2 body posteriorly.
image Stabilizes atlantoaxial joints

• Alar ligaments

image From head of dens to occipital bone above foramen magnum
image Limit rotation of head/atlantoaxial joint

Nerves and Vessels of Spine and Cord

Spinal Cord and Nerves

• Spinal cord and meningeal sheaths adjoin inner bone of bodies, pedicles, laminae in vertebral canal and are susceptible to trauma with fractures.
• Epidural space separates dura from periosteum and ligaments of vertebral canal.
• C1-C7 spinal nerves and ganglia exit canal above numbered vertebral arch or pedicle.
• C8 lies below C7 pedicle, above T1.
• Spinal nerves T1 and below exit below the pedicles of the same-numbered vertebrae.
• Because the cord is shorter than the length of vertebral canal, cervical roots exit more laterally than those below.
• Phrenic nerve (C3-C5 segments): cord injuries at or above C4 can cause diaphragmatic paralysis.
• Upper limb enlargement (C5-T1 cord; for brachial plexus)

image About same level as cervical vertebrae
image Cord injuries at or above these segments compromise upper limb (and lower) musculature and sensation.

• Conus medullaris (adult): inferior tip of spinal cord typically lies ~ mid-body L2 level.
• Lower limb enlargement (L3-S1 cord for lumbosacral plexus)

image At levels of lower thoracic and uppermost lumbar vertebrae
image Cord injuries at or above these segments compromise lower limb and pelvic musculature and sensation.

• Lumbosacral roots travel nearly vertically to individual vertebral foramina: posterior L4 herniation typically spares L4 roots and compresses closer L5 and S1 roots within dural sac.
• L4 and L5 (suprasacral) discs are the most susceptible to herniation.

Vessels

image

Spinal Cord and Nerves In Situ

Arteries of the Spine and Cord

• Vertebrae are supplied by periosteal and equatorial branches of major cervical and thoracoabdominal arteries.

image Cervical: vertebral artery and ascending cervical artery
image Thoracic: posterior intercostal artery branches
image Lumbar: subcostal and lumbar arteries
image Sacrum and coccyx: iliolumbar, lateral, and medial sacral arteries

• Spinal cord is supplied by longitudinal anterior (1) and posterior spinal (2) arteries, arising superiorly from vertebral arteries.
• Spinal arteries receive segmental input from segmental spinal and radicular branches of cervical and thoracoabdominal arteries (e.g., aorta).
• Radicular and segmental anastomoses do not occur at every spinal level, favoring cervical and lumbosacral limb enlargements of cord.
• Largest segmental, great anterior medullary artery (Adamkiewicz) supplies ~2/3 of cord, 65% left only, at lower thoracic or lumbar level.

Venous Drainage

• Venous drainage parallels the arteries.
• Anterior external plexus: drain basivertebral veins from bodies.
• Posterior external plexus: around spines
• Internal (epidural) plexus

image Anterior and posterior networks lining vertebral canal
image Anterior also drains basivertebral veins.

• Plexuses connect to azygous system, cervical, lumbar veins and may be dilated with caval obstruction or portal hypertension.

Clinical Correlates

image

Herniation of Lumbar Disc

image

Vertebral Dislocations

Three-Column Concept for Vertebral Fractures

• Anterior column: anterior half of vertebral body + anterior longitudinal ligament
• Middle column: posterior half of vertebral body + posterior longitudinal ligament
• Posterior column: facet joints, laminae, spines, interspinous ligament
• Fracture is unstable if >1 column is disrupted.
• Anterior column compression (wedge) fractures are usually considered stable.
• Burst fractures are considered unstable.
image

Cervical Vertebral Fractures

Cervical Fractures

• C1 burst (Jefferson): caused by axial forces
• C2 hangman’s: caused by extension, distraction
• C2 odontoid

image Type I: above base, stable
image Type II: at base, unstable
image Type III: extends into body, unstable

Thoracolumbar Fractures

• Thoracolumbar junction is the most mobile spinal segment and most common site of injury.
• Associated trunk and limb injuries are common.
• Neurologic injuries are often complete in thoracic spine trauma.
• Thoracolumbar junction–level spinal injuries can damage the conus medullaris.
• Lumbar spine injuries typically affect roots of the cauda equina.
image

Spondylosis and Spondylolisthesis

Sacral Fractures

• Sacral fractures are typically associated with other fractures of the pelvis (e.g., motor vehicle accidents).
• See Pelvic Fractures for more information.

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