| 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) |
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| 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) |
| annulus tympanicus | In the foetus, a more or less complete bony ring at the medial end of the cartilaginous external acoustic meatus, to which is attached the tympanic membrane. Synonym: annulus tympanicus, tympanic bone. (05 Mar 2000) |
| annulus umbilicalis | An opening in the linea alba through which pass the umbilical vessels in the foetus; in young embryos it is relatively nearer to the pubis, but gradually ascends to the centre of the abdomen; it is closed in the adult, its site being indicated by the umbilicus or navel. Synonym: annulus umbilicalis, canalis umbilicalis. (05 Mar 2000) |
| annulus urethralis | The complete collar of smooth muscle cells of the neck of the urinary bladder which extend distally to surround the preprostatic sportion of the male urethra. There is not a comparable structure in the neck of the femoral bladder; the internal urethral sphincter may exist to prevent reflux of semen into bladder. Synonym: annulus urethralis, internal urethral sphincter, musculus sphincter vesicae, preprostate urethral sphincter, proximal urethral sphincter, sphincter muscle of urinary bladder. (05 Mar 2000) |
| arteria carotis communis | <anatomy, artery> Origin, right from brachiocephalic, left from arch of aorta; runs upward in the neck and divides opposite upper border of thyroid cartilage (C-4 vertebral level) into terminal branches, external and internal carotid. Synonym: arteria carotis communis. (05 Mar 2000) |
| arteria digitalis palmaris communis | <anatomy, artery> One of three arteries arising from the superficial palmar arch and running to the interdigital clefts where each divides into two proper palmar digital arteries. Synonym: arteria digitalis palmaris communis. (05 Mar 2000) |