Radiographic Anatomy of Spine

Radiographic Anatomy of Spine

Radiographic Anatomy of Spine

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Spine Views & Basics - X-Ray Vision Intro

  • X-ray Principles: Bone (dense) = white (radiopaque); Air/soft tissue (less dense) = black/grey (radiolucent).
  • Standard Projections:
    • Anteroposterior (AP): Alignment, vertebral bodies, pedicles.
    • Lateral: Vertebral bodies, disc spaces, curves (lordosis/kyphosis), posterior elements.
    • Oblique: Intervertebral foramina, pars interarticularis (scotty dog).
  • Key Specialized View:
    • Odontoid (Open Mouth): Essential for C1 (atlas), C2 (axis), and dens.

⭐ Standard views include AP, lateral, and obliques; odontoid (open mouth) view is crucial for visualizing C1-C2 articulation and dens.

  • Basic Structures Visualized:
    • Vertebral body
    • Pedicles, laminae
    • Spinous & transverse processes
    • Intervertebral disc spaces

Typical and articulated vertebrae anatomy Lateral Lumbar Spine X-ray with Annotations

Cervical Spine - Neck's Bony Ladder

  • 7 vertebrae; lordotic.
  • Key Lines (Lateral X-ray): 📌 APSL
    • Anterior Vertebral (AVL)
    • Posterior Vertebral (PVL)
    • Spinolaminar (SLL)
  • Prevertebral Soft Tissue (PVST):
    • C1 (Nasoph.): <10mm
    • C2-C4 (Retroph.): <7mm
    • C5-C7 (Retrotrach.): <22mm (A), <14mm (C)
  • Atlanto-Dens Interval (ADI):
    • Adults: <3mm
    • Children: <5mm

⭐ The Atlanto-Dens Interval (ADI) normally measures <3mm in adults and <5mm in children; widening suggests C1-C2 instability, often seen in trauma or rheumatoid arthritis.

Lateral Cervical Spine X-ray with Soft Tissue

Comparison: C1 vs C2 vs Typical (C3-C6)

FeatureC1 (Atlas)C2 (Axis)Typical (C3-C6)
BodyNoHas DensSmall
Spinous Proc.No (tubercle)Large, bifidShort, bifid
Trans. ForaminaYes (VA)Yes (VA)Yes (VA)
UniqueRing, Occip. facetsOdontoidStandard

Thoracic & Lumbar Spine - Trunk Support System

  • Thoracic Spine (T1-T12): Supports rib cage.
    • Body: Heart-shaped. Spinous processes: Long, point down.
    • Key feature: Costal facets for rib articulation (costovertebral & costotransverse joints).
    • Views:
      • AP: Alignment, pedicles.
      • Lateral: Kyphotic curve, vertebral body height, disc spaces.
  • Lumbar Spine (L1-L5): Major weight-bearing.
    • Body: Large, kidney-shaped. Spinous processes: Short, thick, posterior.
    • Oblique view: Key for "Scottie dog" sign (pars interarticularis).
      • 📌 Scottie Dog: Eye-pedicle, Nose-transverse process, Ear-superior articular process, Neck-pars interarticularis, Leg-inferior articular process.

Thoracic spine AP and lateral radiographs with anatomy

FeatureThoracic VertebraeLumbar Vertebrae
Body ShapeHeart-shapedKidney-shaped, large
Spinous ProcessLong, points inferiorlyShort, thick, points posteriorly
Transverse ProcessArticulates with ribs (costal facets)Prominent, no rib facets
Primary CurveKyphoticLordotic
Key View FeatureCostovertebral joints"Scottie dog" (oblique)

Sacrum, Coccyx & Curves - Tail End Tales

  • Sacrum: 5 fused vertebrae (S1-S5), triangular.
    • Articulates: L5 (lumbosacral joint), ilia (sacroiliac joints).
    • Features: Promontory (S1 anterior edge), sacral canal, 4 pairs anterior/posterior foramina (nerves/vessels).
    • Dorsal surface: Median, intermediate, lateral sacral crests.
  • Coccyx: 3-5 fused rudimentary vertebrae (Co1-Co5), tailbone.
    • Articulates: Apex of sacrum.
    • Lacks pedicles, laminae, spinous processes.
  • Spinal Curves (Physiological):
    • Primary (kyphotic): Thoracic, Sacral (concave anteriorly; present at birth).
    • Secondary (lordotic): Cervical, Lumbar (convex anteriorly; develop postnatally).
      • Cervical: develops with head control.
      • Lumbar: develops with walking.

⭐ Ferguson's angle (lumbosacral angle): Formed by intersection of sacral base line & horizontal line. Normal: 30-40 degrees. ↑ angle may indicate spondylolisthesis risk.

AP and Lateral Radiographs of Sacrum and Coccyx Sagittal X-ray of spine with physiological curvatures

High‑Yield Points - ⚡ Biggest Takeaways

  • Identify normal spinal curvatures: cervical/lumbar lordosis, thoracic kyphosis.
  • Pedicles ("owl's eyes" on AP view) are key indicators of bony destruction.
  • Vertebral alignment lines (anterior, posterior, spinolaminar) detect spondylolisthesis.
  • "Scottie dog" sign on oblique lumbar views indicates pars interarticularis defect.
  • Critical C1/C2 anatomy: Atlas, Axis, and Odontoid process.
  • Note intervertebral disc space height; narrowing suggests degenerative disc disease.
  • Spinous processes: bifid in cervical (C2-C6), point inferiorly in thoracic_._

Practice Questions: Radiographic Anatomy of Spine

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Bamboo spine with sacroilitis -

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Flashcards: Radiographic Anatomy of Spine

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_____ bladder is one whos normal round or ovoid shape has been extrinsically compressed to resemble a pear.

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_____ bladder is one whos normal round or ovoid shape has been extrinsically compressed to resemble a pear.

Pear-shaped (or tear-drop-shaped)

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