Supratentorial and Infratentorial

Classification of Supratentorial and Infratentorial

Ashley Davidoff MD

Introduction

The tentorium represents the dividing line between the supratentorial and infratentorial structures.

This classification sometimes is used as a practical way to group the forebrain structures with high level function which lie above the tentorium and the hindbrain structures which are more involved with basic functions of the autonomic nervous system and movement. The midbrain lies between and has some portions above and some below the tentorium.

Space Position and the Tentorium in the Coronal Plane

In this conceptual coronal drawing the distinction between the supratentorial and infratentorial space is made apparent by the bright pink tentorium that acts as a roof of the posterior fossa. The forebrain and the upper part of the midbrain lie above the tentorium, and the lower midbrain and hindbrain lie below. All the structures above the pink line are classified as supratentorial structures , and those below are infratentorial.

Supratentorial and Infratentorial Structures

In this T2 weighted coronal MRI image the distinction between the supratentorial and infratentorial structures is made apparent by the bright pink tentorium that acts as a roof of the posterior fossa. The forebrain (green) midbrain (orange) and hindbrain (pink salmon and maroon) and the cerebellum (maroon), with other parts of the hindbrain filled in including the pons (light pink) middle cerebellar peduncles (mauve) and medulla (salmon) All the structures above the pink line are supratentorial, and those below are infratentorial. Part of the midbrain is supratentorial and part is infratentorial. The ventricular system is outlined in blue code brain