The Inferior rolandic point (IRP) is anatomically situated just below the Rolandic central sulcus (CS) just over the sylvian fissure SyF. This point is situated 2-2.5 cm posterior to the anterior sylvian point (ASP). The IRP also corresponds to the anterior limit of the Transverse temporal gyrus (also called Heschl's gyri or Heschl's convolutions) (TGH) (primary auditory area), this gyrus is allways “kissing” the postcentral gyrus (primary sensory area). The TGH on the surface of the superior temporal gyrus corresponds to Wernicke's area on the dominat hemisphere wich extends posteriorly to the angular Gyrus.

The temporal lobectomy should never surpass the IRP in order to preserve Wernicke´s area.

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The IRP In relation with the cranium, lies at the junction of a vertical line just anterior to the tragus (approximately 4cm above the tragus) and the most superior part of the squamous suture (superior squamous point). Another way to get to the same point (IRP) is to measure 2.5 cm posterior to the Pterion over the squamous suture line as referred by Rhoton Jr.

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The distance between the anterior sylvian point (ASP) and the IRP along the sylvian fissure (SF) is 2.3 cm.

IRP is 2.5 cm posterior to the pterion on the sylvian fissure line.

This point is situated 2-2.5 cm posterior to the Anterior Sylvian Point (ASP).

Considering that the IRP indicates the position of the Heschl Gyrus, removal of the superior and middle temporal gyri posterior to the IRP in the dominant hemisphere has a high risk of permanent dysphasia because it corresponds to the Wernicke Area.