| syndrome, third and fourth pharyngeal pouch | See syndrome, digeorge. (12 Dec 1998) |
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| 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) |
| 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) |
| fourth turbinated bone | A small concha frequently present on the posterosuperior part of the lateral nasal wall; it overlies the supreme nasal meatus. Synonym: concha nasalis suprema, fourth turbinated bone, highest concha, highest turbinated bone, Santorini's concha, concha santorini, supraturbinal, supreme concha, supreme turbinated bone, turbinated body. (05 Mar 2000) |
| Arantius' ventricle | Inferior part of the rhomboid fossa; the narrow lower end of the fourth ventricle between the two clavae. Synonym: Arantius' ventricle. Origin: L. Writing pen (05 Mar 2000) |
| bulb of lateral ventricle | A rounded elevation in the dorsal part of the medial wall of the posterior horn of the lateral ventricle, produced by the major forceps. (05 Mar 2000) |
| bulb of posterior horn of lateral ventricle of brain | Bulb of posterior horn of lateral ventricle of the brain; a curved elevation on the inner wall of the posterior horn produced by the fibres of the forceps major of the corpus callosum as they bend backward into the occipital lobe. Synonym: bulb of posterior horn of lateral ventricle of brain. (05 Mar 2000) |
| ventricle | <anatomy> The paired (right and left) more muscular chambers of the heart that pump blood into the pulmonary (right ventricle) and systemic (left ventricle) circulation. (27 Sep 1997) |
| ventricle of cerebral hemisphere | A cavity shaped somewhat like a horseshoe in conformity with the general shape of the hemisphere; each lateral ventricle communicates with the third ventricle through the interventricular foramen of Monro, and expands from there forward into the frontal lobe as the anterior horn as well as caudally over the thalamus as the central part or cella media which, behind the thalamus, curves ventrally and laterally, then forward into the temporal lobe as the inferior horn; from the apex of the curve a variably sized posterior horn extends back into the white matter of the occipital lobe. The large choroid plexus of the lateral ventricle invades the cella media and the inferior horn (but not the anterior and posterior horn) from the medial side. Synonym: ventriculus lateralis, ventricle of cerebral hemisphere. (05 Mar 2000) |