| opening to cerebral aqueduct | Entrance to the cerebral aqueduct (of Sylvius) from the caudal part of the third ventricle. Synonym: aditus ad aqueductum cerebri, Bartholin's anus, opening to cerebral aqueduct. (05 Mar 2000) |
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| orbital opening | The somewhat quadrangular anterior entrance to the orbit which forms the base of the pyramid-shaped orbital cavity. It is bounded by the sharp supra-, infra-, and lateral orbital margins and a less obvious medial margin on each side of the upper nose. Synonym: aditus orbitae, aperture of orbit. (05 Mar 2000) |
| tendinous opening | The aperture in the aponeurotic insertion of the adductor magnus that transmits the femoral artery and vein from the adductor canal to the popliteal space. Synonym: hiatus tendineus, hiatus adductorius, femoral opening, tendinous opening. (05 Mar 2000) |
| tympanic opening of auditory tube | An opening in the anterior part of the tympanic cavity below the canal for the tensor tympani muscle. Synonym: ostium tympanicum tubae auditivae, tympanic opening of eustachian tube. (05 Mar 2000) |
| tympanic opening of canaliculi for chorda tympani | The small canal opening found lateral to the pyramidal eminence in the posterior wall of the middle ear cavity from which the chorda tympani nerve emerges to pass anteriorly between the ossicles accompanied by a branch of the stylomastoid artery. Synonym: apertura tympanica canaliculi chordae tympani. (05 Mar 2000) |
| tympanic opening of eustachian tube | An opening in the anterior part of the tympanic cavity below the canal for the tensor tympani muscle. Synonym: ostium tympanicum tubae auditivae, tympanic opening of eustachian tube. (05 Mar 2000) |
| external opening of urethra | The slitlike opening of the urethra in the glans penis, the external orifice of the urethra (in the female) in the vestibule, usually upon a slight elevation, the papilla urethrae. Synonym: ostium urethrae externum, external opening of urethra, meatus urinarius, orificium urethrae externum. (05 Mar 2000) |
| femoral opening | The aperture in the aponeurotic insertion of the adductor magnus that transmits the femoral artery and vein from the adductor canal to the popliteal space. Synonym: hiatus tendineus, hiatus adductorius, femoral opening, tendinous opening. (05 Mar 2000) |
| ureteral opening | The opening of the ureter in the bladder, situated one at each lateral angle of the trigone; wide gaping of the ostium usually indicates vesicoureteral reflux. Synonym: ostium ureteris, orificium ureteris, ureteral meatus, ureteral opening. (05 Mar 2000) |
| uterine opening of uterine tubes | The uterine opening of the oviduct. Synonym: ostium uterinum tubae, ostium internum, uterine opening of uterine tubes. (05 Mar 2000) |
| lacrimal opening | The minute circular opening of the lacrimal canaliculus, on the margin of each eyelid near the medial commissure. Synonym: punctum lacrimale, lacrimal opening. (05 Mar 2000) |
| acute reflex bone atrophy | Atrophy of bones, commonly of the carpal or tarsal bones, following a slight injury such as a sprain. See: causalgia, reflex sympathetic dystrophy. Synonym: acute reflex bone atrophy, posttraumatic osteoporosis, Sudeck's syndrome. Origin: L. English sweat (05 Mar 2000) |
| air-bone gap | The difference between the threshold for hearing acuity by bone conduction and by air conduction. (05 Mar 2000) |
| Albrecht's bone | A small bone between the basioccipital and basisphenoid. (05 Mar 2000) |
| allogeneic bone marrow transplant | <haematology, procedure> A bone marrow transplant using marrow collected from a matched healthy donor, usually a brother or sister. The risks associated with the transplant increase with age and 50 years of age is generally regarded as the upper limit. (13 Nov 1997) |