| 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) |
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| 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) |
| ostium aortae | The opening from the left ventricle into the ascending aorta; it is guarded by the aortic valve. Synonym: ostium aortae, aortic ostium. (05 Mar 2000) |
| arcus pedis longitudinalis pars lateralis | Formed by calcaneus, cuboid and two lateral metatarsals; the combined arch is supported normally by ligaments, intrinsic muscles, and the tendons of extrinsic muscles of the foot. Synonym: arcus pedis longitudinalis pars lateralis. (05 Mar 2000) |
| arcus pedis longitudinalis pars medialis | Formed by the calcaneus, talus, navicular, three cuneiform bones, and the three medial metatarsals. Synonym: arcus pedis longitudinalis pars medialis. (05 Mar 2000) |
| pars | A part; a portion. Origin: L. Pars (part-) a part (05 Mar 2000) |
| pars abdominalis ductus thoracici | The part of the thoracic duct between the cisterna chyli and the aortic hiatus of the diaphragm. Synonym: pars abdominalis ductus thoracici. (05 Mar 2000) |
| pars abdominalis oesophagi | The part of the oesophagus inferior to the diaphragm. See: oesophagus. Synonym: pars abdominalis oesophagi. (05 Mar 2000) |
| pars abdominalis ureteris | The part of the ureter between the renal pelvis and the brim of the pelvis. Synonym: pars abdominalis ureteris. (05 Mar 2000) |
| pars alaris musculi nasalis | <anatomy> See: nasalis muscle. Synonym: pars alaris musculi nasalis. (05 Mar 2000) |
| pars alveolaris mandibulae | The portion of the body of the mandible that surrounds and supports the lower teeth. Synonym: pars alveolaris mandibulae. (05 Mar 2000) |
| pars amorpha | The part of the nucleolus that occupies irregular spaces in the nucleolonema and contains finely filamentous substance. See: pars granulosa. (05 Mar 2000) |
| pars annularis vaginae fibrosae | One of the two circular fibrous bands of the fibrous sheaths of the fingers and toes attached to the shaft of the proximal and middle phalanges. Synonym: pars annularis vaginae fibrosae, annular pulley, annulus of fibrous sheath, ligamentum annulare digitorum. (05 Mar 2000) |
| pars anterior | The portion of a structure that tlies most forward, or closest to the front surface relative to other parts; in human anatomy, the ventral portion of a structure. See: anterior part of anterior commissure of brain, anterior part of diaphragmatic surface of liver, anterior part of fornix of vagina. Synonym: pars anterior. (05 Mar 2000) |