During passive cervical rotation to the right, where is the vertebral artery compressed?

• A. Between the first and second cervical vertebra on the right
• B. Between the first and second cervical vertebra on the left
• C. At the base of the skull
• D. In the thoracic outlet

Answer: (B)

During passive cervical rotation to the right, the vertebral artery is at risk of compression on the left side, specifically between the first and second cervical vertebra, which are the atlas (C1) and the axis (C2). This occurs because of the anatomical positioning and the mechanics of cervical rotation.

When the head turns to the right, the left vertebral artery, which courses superiorly through the transverse foramina of the cervical vertebrae, can become angulated or compressed as it passes around the atlantoaxial joint. This is primarily due to the movement mechanics where the atlas rotates on the axis, creating a tightening effect on the artery as it transitions between these two vertebrae. The right rotation leads to the left artery being stretched and potentially compressed against the bony structures.

This understanding is critical for recognizing the implications during cervical spine assessments and interventions, which need to be executed with caution to avoid compromising cerebral blood flow due to vertebral artery occlusion.