| parallel track | <pharmacology> A system for distributing certain experimental drugs to people who are unable to participate in ongoing clinical trials. (09 Oct 1997) |
|---|---|
| extinction parallel | <microscopy> Vibration directions parallel and perpendicular to the long direction of the crystal or fibre. (05 Aug 1998) |
| vein of lateral recess of fourth ventricle | A small vein originating in the cerebellar tonsil, coursing by the lateral recess of the fourth ventricle on its way to terminate in the petrosal vein. Synonym: vein of lateral recess of fourth ventricle. (05 Mar 2000) |
| medial aperture of the fourth ventricle | The large midline opening in the posterior inferior part of the roof of the fourth ventricle, connecting the ventricle with the cerebellomedullary cistern. Synonym: apertura mediana ventriculi quarti, arachnoid foramen, Magendie's foramen, median aperture of the fourth ventricle. (05 Mar 2000) |
| median aperture of the fourth ventricle | The large midline opening in the posterior inferior part of the roof of the fourth ventricle, connecting the ventricle with the cerebellomedullary cistern. Synonym: apertura mediana ventriculi quarti, arachnoid foramen, Magendie's foramen, median aperture of the fourth ventricle. (05 Mar 2000) |
| median sulcus of fourth ventricle | <anatomy> The shallow midline groove in the floor of the ventricle. Synonym: sulcus medianus ventriculi quarti. (05 Mar 2000) |
| medullary striae of fourth ventricle | Slender fascicles of fibres extending transversally below the ependymal floor of the ventricle from the median sulcus to enter the inferior cerebellar peduncle. They arise from the arcuate nuclei on the ventral surface of the medullary pyramid. Synonym: striae medullares ventriculi quarti, acoustic striae, auditory striae, Bergmann's cords, medullary teniae, teniae acusticae. (05 Mar 2000) |
| choroid plexus of fourth ventricle | One of two vascular fringes of pia mater projecting on either side from the lower part of the roof of the fourth cerebral ventricle. Synonym: plexus choroideus ventriculi quarti. (05 Mar 2000) |
| choroid tela of fourth ventricle | The sheet of pia mater covering the lower part of the ependymal roof of the fourth ventricle. Synonym: tela choroidea ventriculi quarti, tela choroidea inferior. (05 Mar 2000) |
| roof of fourth ventricle | Roof of fourth ventricle, formed in its upper part by the superior medullary velum stretching between the two brachia conjunctiva (superior cerebellar peduncles), in its lower part by the inferior medullary velum composed of the choroid membrane and choroid plexus of the fourth ventricle. Synonym: roof of fourth ventricle. (05 Mar 2000) |
| syndrome, third and fourth pharyngeal pouch | See syndrome, digeorge. (12 Dec 1998) |
| tenia of fourth ventricle | The line of attachment of the choroid roof to the rim of the fourth ventricle. Synonym: tenia of fourth ventricle. (05 Mar 2000) |
| third and fourth pharyngeal pouch syndrome | <syndrome> Also called the digeorge syndrome (dgs), this disorder is characterised by (1) low blood calcium levels (hypocalcaemia) due to underdevelopment (hypoplasia) of the parathyroid glands which control calcium; (2) underdevelopment (hypoplasia) of the thymus, an organ behind the breastbone in which lymphocytes mature and multiply; and (3) defects of the heart involving the outflow tracts more than from the heart. most cases of dgs are due to a microdeletion in chromosome band 22q11.2. A small number of cases have defects in other chromosomes, notably 10p13. Named after the american paediatric endocrinologist angelo digeorge. Another name for dgs is hypoplasia of the thymus and parathyroids. (12 Dec 1998) |
| lateral aperture of the fourth ventricle | One of the two lateral openings of the fourth ventricle into the subarachnoid space at the cerebellopontine angle. Synonym: apertura lateralis ventriculi quarti, foramen lateralis ventriculi quarti, foramen of Key-Retzius, foramen of Luschka, Retzius' foramen. (05 Mar 2000) |
| fourth cranial nerve | <anatomy, nerve> The trochlear nerve controls an extraocular muscle. Lesions of this nerve will result in rotation of the eyeball upward and outward (and double vision). Synonym: cranial nerve IV. (27 Sep 1997) |