| 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) |
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| 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) |
| anterior fovea | A slight depression in the limiting sulcus on either side of the rhomboidal fossa, above the medullary striae and lateral to the facial colliculus. Synonym: fovea superior, anterior fovea, fovea anterior. (05 Mar 2000) |
| central retinal fovea | A depression in the centre of the macula retinae containing only cones and lacking blood vessels. Synonym: fovea centralis retinae, central pit. (05 Mar 2000) |
| Morgagni's fovea | The terminal dilated portion of the urethra in the glans penis. Synonym: fossa navicularis urethrae, fossa terminalis urethrae, Morgagni's fossa, Morgagni's fovea. (05 Mar 2000) |
| pterygoid fovea | A depression on the antero-medial side of the neck of the condylar process of the mandible, giving attachment to the lateral pterygoid muscle. Synonym: fovea pterygoidea, pterygoid depression, pterygoid pit. (05 Mar 2000) |
| superior fovea | A slight depression in the limiting sulcus on either side of the rhomboidal fossa, above the medullary striae and lateral to the facial colliculus. Synonym: fovea superior, anterior fovea, fovea anterior. (05 Mar 2000) |
| inferior fovea | A small depression in the limiting sulcus of the rhomboidal fossa below the medullary striae of either side, generally lateral to the hypoglossal and vagal trigones. Synonym: fovea inferior. (05 Mar 2000) |
| oblong fovea of arytenoid cartilage | A broad shallow depression on the anterolateral surface of the arytenoid cartilage, for attachment of the thyroarytenoid muscle. Synonym: fovea oblonga cartilaginis arytenoideae, oblong pit of arytenoid cartilage. (05 Mar 2000) |