Lunate sulcus

The lunate sulcus (a.ka. simian sulcus or the sulcus lunatus) is a cerebral sulcus visible on the outer surface of the occipital lobe. It extends across a significant portion of the occipital lobe's side, closer to its rear, and typically has a vertical alignment. Sometimes, the lunate sulcus may appear as a single continuous sulcus, or it can consist of several separate sulci merging together to create an irregular but continuous ‘composite lunate sulcus’ on the side of the occipital lobe.

It is crucial to differentiate the lunate sulcus from the transverse occipital sulcus, which is a continuation of the intraparietal sulcus on the outer surface of the occipital lobe. The transverse occipital sulcus forms a T-shaped ending on the occipital lobe's lateral surface.