| annulus femoralis | The superior opening of the femoral canal, bounded anteriorly by the inguinal ligament, posteriorly by the pectineus muscle, medially by the lacunar ligament, and laterally by the femoral vein. Passageway by which many lymphatics from lower limb pass to abdomen. Accommodates enlargement of femoral vein in Valsalva manoeuvre. Often occupied by a lymph node (Cloquet's) and is the site of femoral hernias. Synonym: annulus femoralis, crural ring. (05 Mar 2000) |
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| annulus fibrocartilagineus membranae tympani | fibrocartilaginous ring of tympanic membrane |
| annulus fibrosus | One of four fibrous rings that surround atrioventricular and arterial orifices of the heart, providing attachment for the valve leaflets and maintaining patency of the orifice. As part of the fibrous skeleton of the heart, the fibrous rings also provide origin and insertion for the myocardium. Synonym: annulus fibrosus cordis, annulus fibrosus, coronary tendon, fibrous ring, Lower's ring. (05 Mar 2000) |
| annulus fibrosus cordis | One of four fibrous rings that surround atrioventricular and arterial orifices of the heart, providing attachment for the valve leaflets and maintaining patency of the orifice. As part of the fibrous skeleton of the heart, the fibrous rings also provide origin and insertion for the myocardium. Synonym: annulus fibrosus cordis, annulus fibrosus, coronary tendon, fibrous ring, Lower's ring. (05 Mar 2000) |
| annulus fibrosus disci intervertebralis | The ring of fibrocartilage and fibrous tissue forming the circumference of the intervertebral disc; surrounds the nucleus pulposus, which is prone to herniation when the annulus fibrosus is compromised. Synonym: annulus fibrosus disci intervertebralis, annulus fibrosus, fibrous ring of intervertebral disc, fibrous ring. (05 Mar 2000) |
| annulus fibrosus of intervertebral disc | The ring of fibrocartilage and fibrous tissue forming the circumference of the intervertebral disc; surrounds the nucleus pulposus, which is prone to herniation when the annulus fibrosus is compromised. Synonym: annulus fibrosus disci intervertebralis, annulus fibrosus, fibrous ring of intervertebral disc, fibrous ring. (05 Mar 2000) |
| annulus haemorrhoidalis | The part of the anal canal that contains the rectal venous plexus. Synonym: annulus haemorrhoidalis, zona haemorrhoidalis. (05 Mar 2000) |
| annulus inguinalis profundus | The opening in the transversalis fascia through which the ductus deferens (or round ligament in the female) and gonadal vessels enter the inguinal canal. Located midway between anterior superior iliac spine and pubic tubercle, it is bounded medially by the lateral umbilical ligament (inferior epigastric vessels) and inferiorly by the inguinal ligament. Indirect inguinal hernias exit the abdominal cavity via the deep inguinal ring Synonym: annulus inguinalis profundus, abdominal ring, annulus abdominalis, internal inguinal ring. (05 Mar 2000) |
| annulus inguinalis superficialis | The slit-like opening in the aponeurosis of the external oblique muscle of the abdominal wall through which the spermatic cord (round ligament in the female) and inguinal hernias emerge from the inguinal canal. See: aponeurosis of external abdominal oblique muscle. Synonym: annulus inguinalis superficialis, external inguinal ring, subcutaneous ring. (05 Mar 2000) |
| annulus iridis | Either of two zones on the anterior surface of the iris, separated by a circular line concentric with the pupillary border. Synonym: annulus iridis. (05 Mar 2000) |
| annulus iridis major | The outer, broader of the two zones of the iris. Synonym: annulus iridis major. (05 Mar 2000) |
| annulus iridis minor | The narrow inner zone of the iris. Synonym: annulus iridis minor. (05 Mar 2000) |
| annulus lymphaticus cardiae | A group of lymph nodes surrounding the cardia of the stomach. Synonym: annulus lymphaticus cardiae, cardiac lymphatic ring. (05 Mar 2000) |
| annulus of fibrous sheath | 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) |
| annulus ovalis | A muscular ring surrounding the fossa ovalis in the wall of the right atrium of the heart. Synonym: annulus ovalis, margin of fossa ovalis, Vieussens' annulus, Vieussens' isthmus, Vieussens' limbus, Vieussens' ring. (05 Mar 2000) |