Longitudinal fissure Longitudinal fissure The longitudinal fissure (or cerebral fissure, median longitudinal fissure, or interhemispheric fissure) is the deep groove that separates the two hemispheres of the vertebrate brain. The medial surfaces of the two hemispheres are as similarly convoluted by gyri and sulci as is the outer surface of the brain. It is thought that a majority of existing animals, including Homo sapiens, have evolved from a common wormlike ancestor that lived around 600 million years ago, called the urbilaterian. A bilaterian animal is one that has symmetrical left and right body halves. While it is still debated whether this species
Superior orbital fissure the cavernous sinus. Superior orbital fissure syndrome, also known as Rochon-Duvigneaud's syndrome, is a neurological disorder that results if the superior orbital fissure is fractured. Involvement of the cranial nerves that pass through the superior orbital fissure may lead to diplopia, paralysis of extraocular muscles, exophthalmos, and ptosis. Blindness or loss of vision indicates involvement of the orbital apex, which is more serious, requiring urgent surgical intervention. Typically, if blindness is present with superior orbital syndrome, it is called orbital apex syndrome. Superior orbital fissure The superior orbital fissure is a foramen in the skull, although strictly it is more