| fornix of the lacrimal sac | Fornix of the lacrimal sac; the upper, blind end of the lacrimal sac that extends above the openings of the lacrimal canaliculi. Synonym: fornix sacci lacrimalis. (05 Mar 2000) |
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| fossa of lacrimal gland | A hollow in the orbital plate of the frontal bone, formed by the overhanging margin and zygomatic process, lodging the lacrimal gland. Synonym: fossa glandulae lacrimalis, fossa of lacrimal gland. (05 Mar 2000) |
| fossa of lacrimal sac | A fossa formed by the lacrimal bone and the frontal process of the maxilla, lodging the lacrimal sac. Synonym: fossa sacci lacrimalis. (05 Mar 2000) |
| abdominal fissure | Congenital failure of the ventral body wall to close. See: celosomia, gastroschisis. (05 Mar 2000) |
| Ammon's fissure | A pearl-shaped opening in the sclera during early embryogenesis. (05 Mar 2000) |
| anal fissure | A tear or superficial laceration that can occur in the mucosa that lines the anal canal. (27 Sep 1997) |
| anterior median fissure of medulla oblongata | The longitudinal groove in the midline of the anterior aspect of the medulla oblongata; it is the medullary equivalent of the anterior median fissure of the spinal cord and ends at the foramen caecum posterius; its caudal part is obliterated by the decussation of the pyramids. Synonym: fissura mediana anterior medullae oblongatae, anteromedian groove. (05 Mar 2000) |
| anterior median fissure of spinal cord | A deep median fissure on the anterior surface of the spinal cord. Synonym: fissura mediana anterior medullae spinalis, anteromedian groove, sulcus ventralis. (05 Mar 2000) |
| antitragohelicine fissure | A fissure in the auricular cartilage between the cauda helicis and the antitragus. Synonym: fissura antitragohelicina. (05 Mar 2000) |
| ape fissure | A small, inconstant semilunar groove on the cortical convexity near the occipital pole, marking the anterior border of the striate cortex (area 17) and considered homologous with the major sulcus of the same name that is a more constant feature of the cerebral cortex in monkeys and apes. Synonym: sulcus lunatus cerebri, ape fissure, lunate fissure, lunate sulcus, simian fissure. (05 Mar 2000) |
| auricular fissure | A fissure separating the tympanic portion from the mastoid portion of the temporal bone; it transmits the auricular branch of the vagus nerve. Synonym: fissura tympanomastoidea, auricular fissure, tympanomastoid suture. (05 Mar 2000) |
| azygos fissure | The four-layered pleural fold that separates the lobus azygos from the rest of the right upper lobe of the lung, seen as an oblique line pointing downward toward the mediastinal shadow in the upper right lung field on a chest radiograph. (05 Mar 2000) |
| Bichat's fissure | The nearly circular fissure corresponding to the medial margin of the cerebral (pallial) mantle, marking the hilus of the cerebral hemisphere, consisting of the callosomarginal fissure and choroidal fissure along the hippocampus, both of which are continuous with the stem of the fissure of Sylvius at the anterior extremity of the temporal lobe. (05 Mar 2000) |
| branchial fissure | A persistent branchial cleft. (05 Mar 2000) |
| Broca's fissure | The fissure surrounding Broca's convolution. (05 Mar 2000) |