| 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) |
| fourth disease | <disease> An exanthem-producing infectious disease of childhood of unknown aetiology. Synonym: Filatov's disease, fourth disease, parascarlatina, scarlatinella, scarlatinoid. (05 Mar 2000) |
| fourth finger | Fourth finger. Synonym: digitus annularis, fourth finger. (05 Mar 2000) |
| fourth heart sound | The sound produced in late diastole in association with ventricular filling due to atrial systole and related to reduced ventricular compliance. It is a low frequency oscillation that may be normal at older ages owing to a physiologic decline in ventricular compliance but is nearly always abnormal at younger ages if it is of high intensity or palpable. It is common in ventricular hypertrophy, particularly with hypertension, and is almost invariable during acute myocardial infarction. Fourth heart sounds may arise from the right or left ventricle or both. Synonym: atrial sound. (05 Mar 2000) |
| fourth lumbar nerve | <anatomy, nerve> The ventral branch of the nerve is forked to enter into the formation of both lumbar and sacral plexuses. Synonym: furcal nerve, nervus furcalis. (05 Mar 2000) |
| fourth parallel pelvic plane | The lower opening of the true pelvis, bounded anteriorly by the pubic arch, laterally by the rami of the ischium and the sacrotuberous ligament on either side, and posteriorly by these ligaments and the tip of the coccyx. Synonym: apertura pelvis inferior, apertura pelvis minoris, fourth parallel pelvic plane, pelvic outlet, pelvic plane of outlet, plane of outlet. (05 Mar 2000) |
| fourth stage of labour | The hour or two after delivery when the tone of the uterus is established and the uterus contracts down again. (12 Dec 1998) |