During a neurosurgical approach, the surgeon identifies the tentorial notch (incisura). Which structure passes through the suprasellar portion of this notch?
- A Optic nerve
- B Oculomotor nerve
- C Midbrain ✓
- D Basilar artery
Correct answer: C. Midbrain
Explanation
The tentorial notch (incisura) is the opening in the tentorium cerebelli through which the midbrain passes, connecting the diencephalon above to the pons below. The oculomotor nerve runs in the lateral wall of the cisterna ambient and pierces the dural edge near the notch. The optic nerve lies anterior to the stalk in the chiasmatic cistern. The basilar artery runs ventral to the midbrain in the interpeduncular cistern. In uncal herniation, the medial temporal lobe herniates through this notch compressing the midbrain.
Reference: Gray's Anatomy, 42nd ed.
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Written and medically reviewed by the StethoPrep medical team.