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. 2019 Jan-Mar;14(1):15–27. doi: 10.4103/ajns.AJNS_158_18

Table 3.

Safe entry zones and surgical approaches to midbrain

Location Craniotomy Surgical approach Safe entry zone
Central/ventral Fronto-orbito zygomatic/pterional Transsylvian Corridor lateral to the emergence of CN III between the SCA and the PCA, and medial to the pyramidal tract
Ventrolateral Fronto-orbito zygomatic/temporal Transsylvian The lateral mesencephalic sulcus, covered by the lateral mesencephalic vein
Subtemporal transtentorial
Posterolateral Suboccipital Lateral supracerebellar infratentorial The lateral mesencephalic sulcus, covered by the lateral mesencephalic vein
Paramedian Extreme-lateral supracerebellar infratentorial
Retrosigmoid
Dorsal - midline Midline Median supracerebellar infratentorial Two narrow horizontal lines immediately above and below the lamina quadrigemina
Suboccipital Occipital transtentorial approach
Occipital

CN – Cranial nerve; SCA – Superior cerebellar artery; PCA – Posterior cerebral artery