| thoracica | <zoology> A division of cirripeds including those which have six thoracic segments, usually bearing six pairs of cirri. The common barnacles are examples. Source: Websters Dictionary (01 Mar 1998) |
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| arcus aortae | The curved portion between the ascending and descending parts of the aorta; it begins as a continuation of the ascending aorta posterior to the sternal angle, runs posteriorly and slightly to the left as it passes over the root of the left lung, and becomes the descending aorta as it reaches and begins to course along the vertebral column; it gives rise to the brachiocephalic trunk, the left common carotid and left subclavian arteries. Any member of the several pairs of arterial channels encircling the embryonic pharynx in the mesenchyme of the brachial arches; there are potentially six pairs, but in mammals the fifth pair is poorly developed or absent. The first and second pairs are functional only in very young embryos; the third pair is involved in the formation of the carotids; the fourth arch on the left is incorporated in the arch of the aorta; the sixth pair forms the proximal part of the pulmonary arteries. A series of arterial channels encircling the embryonic pharynx in the mesenchyme of the branchial arch's. There are potentially six pairs, but in mammals the fifth pair is poorly developed or absent. The first and second pairs are functional only in very young embryos; the third pair is involved in the formation of the carotids; the fourth arch on the left is incorporated in the arch of the aorta; the sixth pair forms the proximal part of the pulmonary arteries. Synonym: arcus aortae. (05 Mar 2000) |
| bifurcatio aortae | The division of the aorta into right and left common iliac arteries; it occurs at the level of the fourth and fifth lumbar vertebral body. Synonym: bifurcatio aortae. (05 Mar 2000) |
| bulbus aortae | The dilated first part of the aorta containing the aortic semilunar valves and the aortic sinuses. Synonym: bulbus aortae, arterial bulb. (05 Mar 2000) |
| valva aortae | The heart valve that divides the left ventricle and the aorta. The aortic valve opens during left ventricular contraction and then closes to prohibit the backwash of oxygenated blood from the aorta into the ventricle. The aortic valve has 3 valve cusps. (27 Sep 1997) |
| valvula semilunaris dextra valvae aortae | Right semilunar cusp of the aortic valve. (05 Mar 2000) |
| valvula semilunaris posterior valvae aortae | Posterior semilunar cusp of the aortic valve. (05 Mar 2000) |
| valvula semilunaris sinistra valvae aortae | Left semilunar cusp of the aortic valve. (05 Mar 2000) |
| rami mediastinales aortae thoracicae | Numerous small arteries supplying the pleura and lymph nodes of the posterior mediastinum. Synonym: rami mediastinales aortae thoracicae, posterior mediastinal arteries. (05 Mar 2000) |
| rami oesophageales aortae thoracicae | Branches arising directly from the anterior aspect of the portion of the thoracic aorta adjacent to the oesophagus, by which most of the oesophagus is supplied. Synonym: rami oesophageales aortae thoracicae. (05 Mar 2000) |
| rami pericardiaci aortae thoracicae | Small branches of thoracic aorta distributed to the pericardium, in the region of the oblique pericardial sinus, and to posterior mediastinal lymph nodes. Synonym: rami pericardiaci aortae thoracicae. (05 Mar 2000) |
| vestibulum aortae | The anterosuperior portion of the left ventricle of the heart immediately below the aortic orifice, having fibrous walls and affording room for the segments of the closed aortic valve. Synonym: Sibson's aortic vestibule, vestibulum aortae. (05 Mar 2000) |
| medionecrosis aortae idiopathica cystica | Loss of elastic and muscle fibres in the aortic media, with accumulation of mucopolysaccharide, sometimes in cystlike spaces between the fibres; a disease of unknown cause, which may be inherited and which predisposes to dissecting aneurysms. Synonym: Erdheim disease, medionecrosis aortae idiopathica cystica, medionecrosis of the aorta, mucoid medial degeneration. (05 Mar 2000) |
| sinus aortae | The space between the superior aspect of each cusp of the aortic valve and the dilated portion of the wall of the ascending aorta, immediately above each cusp. Synonym: sinus aortae, Petit's sinus, Valsalva's sinus. Arlt's sinus, an inconstant depression on the lower portion of the internal surface of the lacrimal sac. Barber's pilonidal sinus, pilonidal sinus occurring in barbers, usually in the web between the fingers, due to the burying of exogenous hairs by the alternate loosening and tightening of tissues of the hand by the manipulation of scissors. (05 Mar 2000) |
| isthmus aortae | A slight constriction of the aorta immediately distal to the left subclavian artery at the point of attachment of the ductus arteriosus. Synonym: isthmus aortae. (05 Mar 2000) |