Fissure

{fish’-ur) [fi ura; findere, to cleave]. A groove or cleft. A term applied to the clefts or grooves in various organs, as the skull, the brain, the liver, the spinal cord. Also to cracks in the skin or linear ulcers in mucous membranes. F. of the Anus, a linear ulcer at the mucocutaneous junction of the anus, giving rise to intense suffering on defecation. F. of Bichat, the transverse fi ure of the brain, between the fornix and the upper surface of the cerebellum. Through it the pia enters the ventricles. F. of Broca, a fi ure surrounding Broca’s lobe. F., Calcarine, a fi ure on the mesal aspect of the cerebrum, between the lingual lobule and the cuneate lobe. F., Callosomarginal, one on the mesal surface of the cerebral hemisphere, dividing the area between the corpus callosum and the margin into nearly equal parts. F., Longitudinal, the deep fi ure that divides the cerebrum into two hemispheres. F., Occipital, a deep fi ure, situated between the parietal and occipital lobes of the brain. F., Palpebral, the space between the eyelids extending from the outer to the inner canthus. F., Portal. See F., ch320.xhtml t 278