Fluoroscopic Spine Anatomy for the 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 and 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


Basic Anatomy

There are generally 5 lumbar vertebrae. 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)

There are generally 3 common views utilized under fluoro. The exact alignment of the c-arm will vary with each level and person. These basic steps help acquire a good enough image for a procedure:

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 levels you’re interested in.
lumbar medial branch block anterior posterior fluoroscopy
Note spinous process mostly aligned vertically and midline (blue). Target here is sacral ala with the needle so the top of sacrum is leveled off (red)

Lateral fluoroscopy view

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).


Cervical imaging can be tricky:

  • Most work (medial branch blocks, epidurals, radiofrequency ablations) is done in the lateral or oblique view (as opposed to an AP view, which is more important for lumbar/thoracic work)
  • If you can obtain good imaging, the procedures will be much smoother:
    • Many factors effect images such as patient size, body habitus, and positioning.
    • Try to position the patient so the neck is in a “long”, neutral position. A twisted neck can make lateral and AP views misaligned.
    • Avoid flexion, except CESIs where you want the head flexed on the neck.
    • Hunched shoulders can obscure the lower levels of the neck in a lateral view.
      • Try to have the shoulders pulled down slightly and/or curled forward to get them out of the way.
    • Obese patients often have fat that limits access to the injection site or obscures the image.
      • If the patient is in a prone position you can tape back pannus: apply tape near the neck and pull down a long strip towards the low back. This pulls down some of the pannus out of the way.
    • Hair can get in the way
      • Have patients wear a bouffant with hair tied inside. All of this can be taped up after positioning.
    • Line up the borders of the lateral mass/articulating column so you don’t see “double images” when the left and right are out of alignment.
    • After obtaining a good lateral view simply rotate the c-arm in one axis to get the AP view. This minimizes motion of the c-arm and wasted time re-establishing images.
Generally well aligned lateral view that’s sufficient for procedures Source: https://radiopaedia.org/


(coming soon)

Naming/Numbering of bony structures and nerve roots

(coming soon)