| superior sagittal sinus | An unpaired dural venous sinus in the sagittal groove, beginning at the foramen caecum and terminating at the confluence of sinuses where it merges with the straight sinus; receives the superior cerebral veins and has lateral extensions, the lateral venous lacunae. Synonym: sinus sagittalis superior, superior longitudinal sinus. Tarsal sinus, a hollow or canal formed by the groove of the talus and the interosseous groove of the calcaneus which is occupied by the interosseous talocalcaneal ligament. Synonym: sinus tarsi, tarsal canal. (05 Mar 2000) |
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| dermal sinus | A sinus lined with epidermis and skin appendages extending from the skin to some deeper-lying structure, most frequently the spinal cord. (05 Mar 2000) |
| inferior longitudinal sinus | An unpaired dural venous sinus in the lower margin of the falx cerebri, running parallel to the superior sagittal sinus and merging with the great cerebral vein to form the the straight sinus. Synonym: sinus sagittalis inferior, inferior longitudinal sinus. (05 Mar 2000) |
| inferior petrosal sinus | A paired dural venous sinus running in the groove on the petrooccipital fissure connecting the cavernous sinus with the superior bulb of the internal jugular vein. Synonym: sinus petrosus inferior, Englisch's sinus. (05 Mar 2000) |
| inferior sagittal sinus | An unpaired dural venous sinus in the lower margin of the falx cerebri, running parallel to the superior sagittal sinus and merging with the great cerebral vein to form the the straight sinus. Synonym: sinus sagittalis inferior, inferior longitudinal sinus. (05 Mar 2000) |
| oblique pericardial sinus | The recess in the pericardial cavity posterior to the base of the heart bounded laterally by the pericardial reflections on the pulmonary veins and inferior vena cava, and posteriorly by the pericardium overlying the anterior aspect of the oesophagus. Synonym: sinus obliquus pericardii, oblique sinus of pericardium. (05 Mar 2000) |
| oblique sinus of pericardium | The recess in the pericardial cavity posterior to the base of the heart bounded laterally by the pericardial reflections on the pulmonary veins and inferior vena cava, and posteriorly by the pericardium overlying the anterior aspect of the oesophagus. Synonym: sinus obliquus pericardii, oblique sinus of pericardium. (05 Mar 2000) |
| occipital sinus | An unpaired dural venous sinus commencing at the confluence of the sinuses and passing downward in the base of the falx cerebelli to the foramen magnum. Synonym: sinus occipitalis. (05 Mar 2000) |
| opening of the sphenoidal sinus | One of the pair of openings in the body of the sphenoid bone through which the sphenoid sinuses communicate with the sphenoethmoidal recess of the nasal cavity. Synonym: apertura sinus sphenoidalis, sphenoidal sinus aperture. (05 Mar 2000) |
| tachycardia, sinus | Fast heartbeat (tachycardia) occurring because of rapid firing by the sa node, the natural pacemaker of the heart. Electrical signals initiated in the sa node are transmitted to the atria and the ventricles to stimulate heart muscle contractions heartbeats. Sinus tachycardia is usually a rapid contraction of a normal heart in response to a condition, drug, or disease. For examples, pain, fever, excessive thyroid hormone, exertion, excitement, low blood oxygen level (hypoxia), or stimulant drugs such as caffeine, cocaine, and amphetamines can cause tachycardia. However, in some cases, it can be a sign of heart failure or heart valve disease or other illness. (12 Dec 1998) |
| tentorial sinus | straight sinus |
| terminal sinus | Sinus terminalis, the vein bounding the area vasculosa in the blastoderm. (05 Mar 2000) |
| Tourtual's sinus | The interval between the palatoglossal and palatopharyngeal arches above the tonsil, most obvious after the tonsil has regressed in the adult. Synonym: fossa supratonsillaris, supratonsillar recess, Tourtual's sinus. (05 Mar 2000) |
| endocervical sinus tumour | Malignant germ cell tumour commonly found in the ovary. The tumour arises from primitive germ cells and develops into extra-embryonic tissue resembling the yolk sac. Synonym: yolk sac carcinoma. (05 Mar 2000) |
| endodermal sinus tumour | An unusual and aggressive tumour of germ-cell origin that reproduces the extraembryonic structures of the early embryo. It is the most common malignant germ cell tumour found in children. It is characterised by a labyrinthine glandular pattern of flat epithelial cells and rounded papillary processes with a central capillary (schiller-duval body). The tumour is rarely bilateral. Before the use of combination chemotherapy, the tumour was almost invariably fatal. (12 Dec 1998) |