(fish'ŭr )

[ fissura, cleft]

1. A groove, natural division, cleft, slit, or deep furrow in the brain, liver, spinal cord, and other organs. SYN: fissura; sulcus.
2. An ulcer or cracklike sore.
3. A break in the enamel of a tooth.

   fissural,

   (fish'ŭ-răl)

   adj.

anal f.A painful linear ulcer on the margin of the anus. It is a common problem in infancy and fairly common in constipated adults.

Conservative, nonoperative care heals most anal fissures. Patients should be advised to drink a lot of water to lubricate stools, adopt a high-fiber diet, and take a stool softener to ease the passage of stool. Sitting in a warm bath several times a day may help relax the anal sphincters. Medicated creams or ointments may provide topical anesthesia to the anus.

Patients who do not improve with medical therapies may require local injection of botulinum toxin to relax the sphincters or surgery to repair chronic fissures.

anterior median f.In the spinal cord, a deep fissure that runs along the anterior midline separating the right and left sides. It contains the anterior spinal artery in its superficial aspect.

auricular f.A fissure of the petrous portion of the temporal bone that separates the tympanic from the mastoid parts. The auricular branch of the vagus nerve passes along the auricular fissure.

branchial f.

SEE: under cleft.

calcarine f.The fissure extending from the occipital end of the cerebrum to the parieto-occipital sulcus. SYN: calcarine sulcus.

central f.Roland o fissure.

cerebellar f.A fissure that consists of deep horizontal grooves that separate the cerebellum into its lobes and lobules.

collateral f.The fissure on the inferior surface of the cerebral hemisphere separating the subcalcarine and subcollateral gyri.

dental f.A fissure in the dental enamel, usually on the occlusal surface.

glaserian f.A narrow fissure posterior to the mand ibular fossa of the temporal bone. The chorda tympani nerve passes through it.

hippocampal f.The fissure extending from the posterior part of the corpus callosum to the tip of the temporal lobe of the brain. SYN: hippocampal sulcus.

horizontal f.Transverse fissure (3).

inferior orbital f.The fissure at the apex of the orbit through which the infraorbital blood vessels and maxillary branch of the trigeminal nerve pass.

interparietal f.Intraparietal sulcus.

lateral f.Sylvian fissure

longitudinal f.1The fissure on the inferior surface of the liver.2A fissure that separates the cerebral hemispheres. The corpus callosum, which connects the hemispheres, is at the base of the fissure.

occipitoparietal f.The fissure between the occipital and parietal lobes of the brain.

palpebral f.The fissure separating the upper and lower eyelids.

portal f.The fissure into the undersurface of the liver. It continues into the liver as the portal canal.

presylvian f.The anterior division of the sylvian fissure.

Roland o f.

SEE: under Roland o, Luigi.

sphenoidal f.

Variant: sphenoid fissure