The lateral sulcus separates the frontal lobe from the temporal lobe. The frontal lobe can be divided into a lateral, polar, orbital (above the orbit; also called basal or ventral), and medial part. Each of these parts consists of a particular gyrus: 1  Lateral part: lateral part of the superior frontal gyrus, middle frontal gyrus, inferior frontal gyrus. 2  Polar part: Transverse frontopolar gyri, frontomarginal gyrus. 3  Orbital part: Lateral orbital gyrus, anterior orbital gyrus, posterior orbital gyrus, medial orbital gyrus, gyrus rectus.
Less common causes of glaucoma include a blunt or chemical injury to the eye, severe eye infection, blockage of blood vessels in the eye, inflammatory conditions of the eye, and occasionally eye surgery to correct another condition.
Normal-tension glaucoma causes. Although its cause is not completely understood, normal-tension glaucoma is generally believed to occur either because of an unusually fragile optic nerve that can be damaged despite a normal pressure inside the eye, or because of reduced blood flow to the optic nerve.1  Unusually fragile optic nerves may be inherited.lthough its cause is not completely understood, normal-tension glaucoma is generally believed to occur either because of an unusually fragile optic nerve that can be damaged despite a normal pressure inside the eye, or because of reduced blood flow to the optic nerve. 1  Unusually fragile optic nerves may be inherited.