Lumbar Spine Fluoroscopic Anatomy for the Pain Management Interventionalist

This article is designed to review all the basics around spine anatomy that would be helpful for performing procedures. Any pain management inverventionalist/proceduralist will rely on this basic anatomy, understanding of fluoroscopy images and C-arm use. It is written with a few basic goals:

  • Review basic vertebrae and spine anatomy
  • Discuss that in the context of fluoroscopic images and C-Arm positioning for procedures
  • Outline basic principles that can set a foundation for the various articles on this site

Quick Guide

Basic Anatomy


There are generally 5 lumbar vertebrae:

  • But keep in mind that some patients can have 4 or 6 lumbar vertebrae.
  • Compare with MRI/CT scans and reports to ensure that your labeling is consistent with other reports/findings.
  • In some patients the bottommost vertebrae can appear “sacralized” or the top of the sacrum can appear “lumbarized”. Again, compare to other imaging to ensure that you are treating the levels that you think you’re treating.

Vertebral Components

Most procedures revolve around knowing the basic structures of the vertebrae in the diagram and are referenced throughout this site:

  • Transverse process (TP)
  • Spinous process (SP)
  • Superior articulating process (SAP)
  • Inferior articulating process (IAP)
  • Neuroforamen (NF)


Remember that the spine has natural curves and sometimes curves from scoliosis. So the C-arm alignment for an AP/lateral/oblique view will be different for each level.

Remember the bullet points listed below for each type of view and move the C-arm to meet these principles.

AP (Anterior-Posterior) fluoroscopy view

  • The spinous processes should be midline.
  • Flatten the endplates at the level that you’re working on.
  • With significant scoliosis you can’t get all SPs midline, so you do so at the level that you’re working at.

EXAMPLE: Same image with/without colored outlines

EXAMPLE: Compare this to the L5 level just above where you can see the endplates are not flattened out (green outlines anterior and posterior components of endplates)

Lateral fluoroscopy view

  • Again, endplates should be flat so the vertebral bodies appear like a box
  • The foamina should be well outlined
L3 lumbar medial branch block technique fluoroscopic lateral view

Oblique/scotty dog fluoroscopy view

  • Attempt to look down the barrel of the facet joint at the level you’re working at. This means you see the facet joint straight on so it is lucent/transparent
  • Scotty dog (highlighted here in green)
  • Nose = TP, ear = SAP, front foot = IAP, body = lamina
scotty dog diagram fluoroscopy left L4
front half of the scotty dog outlined (green), the superior endplate of L4 is flat (red), the L3-L4 joint is “down the barrel” so it’s translucent (blue).

EXAMPLE 1: You want to place a needle at the junction of the TP and SAP at L4 on the left (also known as a left lumbar medial branch block at L4).

Naming/Numbering of bony structures and nerve roots

(coming soon)


  1. Guidelines to Imaging Landmarks for Interventional Spine Procedures: Fluoroscopy and CT Anatomy
    1. Thorough review of basic images and procedure specific considerations.
  2. (More coming soon…)