| 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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| 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) |
| left sagittal fissure | A sagittal groove on the undersurface of the liver formed by the fissura ligamenti teretis anteriorly and the fissura ligamenti venosi posteriorly. (05 Mar 2000) |
| axis | <botany> A stem, commonly used for the main stem of a whole plant or of an inflorescence. (09 Oct 1997) |
| axis bulbi externus | That part of the optic axis from the midpoint of anterior surface of the cornea to the posterior surface of the posterior pole of the external surface of the sclera. Synonym: axis bulbi externus. (05 Mar 2000) |
| axis bulbi internus | <anatomy> That part of the optic axis from the midpoint of the posterior surface of the cornea to the anterior surface of the retina opposite the posterior pole. Synonym: axis bulbi internus. (05 Mar 2000) |
| axis corpuscle | Axile corpuscle, the central portion of a tactile corpuscle. (05 Mar 2000) |
| axis, crystallographic | <microscopy> One of several imaginary lines assumed in describing the positions of the planes by which a crystal is bounded, the positions of the atoms in the structure of the crystal and the directions associated with vectorial and tensorial physical properties. (05 Aug 1998) |
| axis cylinder | An obsolete term for axon. (05 Mar 2000) |
| axis deviation | Deflection of the electrical axis of the heart to the right or left of the normal. See: left axis deviation, right axis deviation, axis. Synonym: axis shift. (05 Mar 2000) |
| axis fracture | <radiology> Incidence: 6% of cervical spine injuries, associated with atlas fractures in 8%, hyperflexion injury: odontoid fracture, type I avulsion of tip of odontoid (5-8%) difficult to detect, type II fracture through base of dens (54-67%) complication: nonunion, type III subdental injury (30-33%) prognosis: good, Differential diagnosis: os odontoideum, ossiculum terminale, hypoplasia/aplasia of dens, hyperextension injury: hangman's fracture (12 Dec 1998) |
| axis lentis | A line connecting the anterior and posterior poles of the lens of the eye. Synonym: axis lentis. (05 Mar 2000) |
| axis ligament of malleus | <anatomy> A ligament forming the axis about which the malleus rotates; it consists of two portions extending from the anterior and the posterior border, respectively, of the tympanic notch to the malleus. Synonym: axis ligament of malleus. (05 Mar 2000) |
| axis of lens | A line connecting the anterior and posterior poles of the lens of the eye. Synonym: axis lentis. (05 Mar 2000) |
| axis of symmetry | An axis through a particle (e.g., a virus) on such a plane that, if the particle is rotated on the axis, there are two or more positions at which the particle appears identical. (05 Mar 2000) |