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
The Body Silent experience muscle spasms in his anus, and in his lower abdomen in 1972, and soon had trouble urinating. He was then diagnosed with an anal fissure, meaning of a slight break in the muscle. After a few years of symptoms, he visited a neurologist and was diagnosed with a benign but slowly growing tumor in the upper part of his spinal cord. Within two years his central nervous system was severely damaged, and lost control of most bodily functions. In 1987, the book was awarded the Columbia University's Lionel Trilling Award. The Body Silent The Body Silent is a personal