Radiographic Anatomy of Spine

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

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.

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

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.

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.

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_._