Learn how to confidently identify spinal anatomy and distinguish oblique versus lateral projections with these easy-to-remember radiographic rules. Perfect for radiography students studying cervical, thoracic, lumbar, and SI joint positioning.
When learning spine anatomy and the differences between oblique and lateral projections, a few consistent rules can make everything click. The guidelines below are designed to simplify joint-space identification and reduce confusion across spinal regions.
Note: Bontrager’s and Merrill’s may differ slightly on certain obliques, so always defer to your program’s requirements when needed.
Core Rules for Obliques & Laterals
RULE #1: Opposite Rule
For obliques and laterals, the joint space of interest is always the OPPOSITE of each other.
Example: A cervical oblique (IF) will never demonstrate the same joint as a lateral (ZJ).
RULE #2: Master the AP Obliques First
If you know the AP oblique, the PA oblique will always be the OPPOSITE. Learn one well, and the other becomes automatic.
RULE #3: Identify the Shape
- Foraminas form a visible “O”
- Zygapophyseal (Z) joints form a “Z” or something similar
Use the shape to confirm what joint you’re seeing.
RULE #4: Memorize “I Z Z S” for Obliques
- I – Cervical Intervertebral foramina
- Z – Thoracic Z-joints
- Z – Lumbar Z-joints
- S – SI joints
Remember: Laterals are always the OPPOSITE.
RULE #5: Remember the Direction Pattern — “UP, UP, DOWN, UP”
Remember: PA is always OPPOSITE (Down, Down, Up, Down)
| Region | Joint in Focus |
|---|---|
| Cervical | Intervertebral foramina on the UPSIDE |
| Thoracic | Z-joints on the UPSIDE |
| Lumbar | Z-joints on the DOWNSIDE |
| SI Joint | SI joint on the UPSIDE |