| unroofed coronary sinus syndrome | <syndrome> A spectrum of cardiac anomalies in which part or all of the common wall between the coronary sinus and the left atrium is absent. (05 Mar 2000) |
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| urogenital sinus | The ventral part of the cloaca after its separation from the rectum by the growth of the urorectal septum; from it develops the lower part of the bladder in both sexes, the prostatic portion of the male urethra, and the urethra and vestibule in the female. Synonym: persistent cloaca. (05 Mar 2000) |
| uterine sinus | A small irregular vascular channel in the endometrium, of a type that forms during pregnancy. Synonym: uterine sinusoid. Uteroplacental sinuses, irregular vascular spaces in the zone of the chorionic attachment to the decidua basalis. (05 Mar 2000) |
| lactiferous sinus | A circumscribed spindle-shaped dilation of the lactiferous duct just before it enters the nipple. In nursing mothers this dilatation stores a droplet of milk which is expressed by compression as the infant begins to suckle; this is thought to encourage continual suckling while the let-down reflex ensues. Synonym: sinus lactiferi, ampulla lactifera, ampulla of milk duct, lactiferous ampulla. (05 Mar 2000) |
| laryngeal sinus | The recess in each lateral wall of the larynx between the vestibular and vocal folds and into which the layrngeal sacculus opens. Synonym: ventriculus laryngis, laryngeal sinus, Morgagni's sinus, Morgagni's ventricle, sinus laryngeus. (05 Mar 2000) |
| lateral sinus | A paired dural venous sinus that drains the confluence of sinuses, running along the occipital attachment of the tentorium cerebelli and terminating in the sigmoid sinus. Synonym: sinus transversus, lateral sinus. Transverse pericardial sinus, a passage in the pericardial sac between the origins of the great vessels, i.e., posterior to the intrapericardial portions of the pulmonary trunk and ascending aorta and anterior to the superior vena cava and superior to the atria; it is formed as a result of the flexure of the heart tube, partially approximating the great venous and arterial vessels. Synonym: sinus transversus pericardii, Theile's canal, transverse sinus of pericardium. (05 Mar 2000) |
| frontal sinus | One of the paired, but seldom symmetrical, air spaces located between the inner and outer compact layers of the frontal bone. (12 Dec 1998) |
| frontal sinus aperture | One of a pair of openings in the floor of the frontal sinuses in the nasal part of the frontal bone, through which the frontal sinuses communicate with the ethmoidal infundibulum via the frontonasal duct. Synonym: apertura sinus frontalis. (05 Mar 2000) |
| longitudinal sinus | See: inferior sagittal sinus, superior sagittal sinus. Longitudinal vertebral venous sinus, large, plexiform veins forming portions of the anterior internal vertebral venous plexus lying on the posterior surfaces of the vertebral bodies on either side of the posterior longitudinal ligament. Synonym: sinus vertebrales longitudinales. Luschka's sinus, venous sinus in the petrosquamous suture. (05 Mar 2000) |
| lymphatic sinus | The channels in a lymph node crossed by a reticulum of cells and fibres and bounded by littoral cells; there are subcapsular, trabecular, and medullary sinus's. Synonym: lymph sinus. Maier's sinus, an infundibuliform depression on the internal surface of the lacrimal sac which receives the lacrimal canaliculi. Marginal sinuses of placenta, discontinuous venous lakes at the margin of the placenta. (05 Mar 2000) |
| lymph sinus | The channels in a lymph node crossed by a reticulum of cells and fibres and bounded by littoral cells; there are subcapsular, trabecular, and medullary sinus's. Synonym: lymph sinus. Maier's sinus, an infundibuliform depression on the internal surface of the lacrimal sac which receives the lacrimal canaliculi. Marginal sinuses of placenta, discontinuous venous lakes at the margin of the placenta. (05 Mar 2000) |
| aditus glottidis superior | Portion of the cavity of the larynx between the vestibular and vocal folds, with which the ventricles communicate. Synonym: aditus glottidis superior. (05 Mar 2000) |
| angulus superior scapulae | Formerly named the medial angle, it lies at the junction of the superior and medial borders of the bone. Synonym: angulus superior scapulae. (05 Mar 2000) |
| ankyloglossia superior syndrome | <syndrome> A congenital condition in which the tongue adheres to the hard palate; no evidence of genetic factors. (05 Mar 2000) |
| anterior superior alveolar arteries | Origin, infraorbital artery within intraorbital canal; distribution, via anterior alveolar canals to upper incisors and canine teeth, mucus membrane of maxillary sinus. Synonym: arteriae alveolares superiores anteriores, anterior superior dental arteries. (05 Mar 2000) |