| 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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| alveolar dead space | The difference between physiologic dead space and anatomical dead space; it represents that part of the physiologic dead space resulting from ventilation of relatively underperfused or nonperfused alveoli; it differs specifically in being placed so as to fill and empty in parallel with functional alveoli, rather than being interposed in the conducting tubes between functional alveoli and the external environment. (05 Mar 2000) |
| anatomical dead space | The volume of the conducting airways from the external environment (at the nose and mouth) down to the level at which inspired gas exchanges oxygen and carbon dioxide with pulmonary capillary blood; formerly presumed to extend down to the beginning of alveolar epithelium in the respiratory bronchioles, but more recent evidence indicates that effective gas exchange extends some distance up the thicker-walled conducting airways because of rapid longitudinal mixing. Compare: alveolar dead space, physiologic dead space. Synonym: anatomical airway. (05 Mar 2000) |
| antecubital space | The fossa in front of the elbow, bounded laterally and medially by the humeral origins of the extensors and flexors of the forearm, respectively, and superiorly by an imaginary line connecting the humeral condyles. Synonym: fossa cubitalis, antecubital space, chelidon, triangle of elbow. (05 Mar 2000) |
| anterior clear space | On lateral chest radiographs, the region dorsal to the sternum and ventral to the ascending aorta. Synonym: anterior clear space. (05 Mar 2000) |
| apical space | The space between the alveolar wall and the apex of the root of a tooth where an alveolar abscess usually has its origin. (05 Mar 2000) |
| axillary space | <anatomy> The underarm area. (16 Dec 1997) |
| Berger's space | The space between the patellar fossa of the vitreous and the lens. (05 Mar 2000) |
| Bogros' space | A triangular space between the peritoneum and the transversalis fascia, at the lower angle of which is the inguinal ligament; it contains the lower portion of the external iliac artery. Synonym: Bogros' space, spatium retroinguinale. (05 Mar 2000) |
| Bottcher's space | The blind pouch at the end of the endolymphatic duct. (12 Dec 1998) |
| Bowman's space | The slitlike space between the visceral and parietal layers of the capsule of the renal corpuscle; it opens into the proximal tubule of the nephron at the neck of the tubule. Synonym: Bowman's space, filtration space. (05 Mar 2000) |
| Burns' space | A narrow interval between the deep and superficial layers of the cervical fascia above the manubrium of the sternum through which pass the anterior jugular veins. Synonym: Burns' space. (05 Mar 2000) |
| capsular space | The slitlike space between the visceral and parietal layers of the capsule of the renal corpuscle; it opens into the proximal tubule of the nephron at the neck of the tubule. Synonym: Bowman's space, filtration space. (05 Mar 2000) |
| Malacarne's space | The bottom of the interpeduncular fossa at the base of the midbrain, extending from the anterior border of the pons forward to the mamillary bodies, and containing numerous openings for the passage of perforating branches of the posterior cerebral arteries. Synonym: substantia perforata posterior, locus perforatus posticus, Malacarne's space. (05 Mar 2000) |
| velocity space | <radiobiology> Mathematical space where each point corresponds not to a certain location in reality, but to a certain velocity. Distribution functions typically involve mixes of both position and velocity spaces. (See distribution function.) Contrast with position space where each point corresponds to a given location. (09 Oct 1997) |