Circular sulcus of insula

The peri-insular circular sulcus of insula is a groove or a sulcus encircling the insula and acting as a boundary between the insula and the temporal, frontal, and parietal lobes. It is not easily observable as it lies hidden beneath the opercula of the frontal, parietal, and temporal lobes.

The peri-insular circular sulcus of insula of three parts or rami: the anterior, superior, and inferior rami or sulci: the anterior, superior, and inferior rami or sulci. The anterior limiting sulcus separates the insula from the frontal cortex, the superior limiting sulcus separates it from the fronto-parietal cortex, and the inferior limiting sulcus separates it from the temporal cortex.

The anterior and superior limiting sulci meet at a point called the anterior insular point, and the superior and inferior sulci meet at another point called the posterior insular point. This creates a triangular shape for the insular cortex. The base of the triangle is between the anterior and posterior insular points, while the apex points downward and outward where the anterior inferior and posterior limiting sulci attempt to meet. However, the union between the anterior inferior and posterior limiting sulci is not complete, and the region between them, located within the lateral sulcus and facing the lesser wing of the sphenoid bone, is known as the limen insulae.