cumference

of the membrana tympani which is fixed in the sulcus tympanic us. a. fibro's us, one of two fibrous rings surrounding the atrioventricular orifices, circulus callosus Halleri. a. fibro's us fibro cart i lag'in is inter vertebra'lis [BNA], the fibrous ring forming the circumference of the intervertebral fibrocartilage. a. htemorrhoidalis, a circular elevation at the termination of Morgagni's rectal columns, corresponding to the location of the external sphincter muscle; it contains the venous anastomoses of the hemorrhoidal plexus, a. inguina'lis abdominal is [BNA], internal abdominal ring, the entrance to the inguinal canal, about half an inch above the center of Poupart 's ligament, a. inguina'lis subcuta'neus [BNA], external abdominal ring, an opening in the aponeurosis of the obliquus extemus just above the spine of the pubis, which transmits the spermatic cord in the male, the round ligament of the uterus in the female. a. ir'idis, ring of the iris, one of two zones on the anterior surface of the iris, separated by a circular line concentric with the pupillary border; the u. irid is minor is the inner of the two zones and is much narrower than the other, a. irid is major, u. mi'grans lin'guce, geographical tongue.* a. ova'lis, limbus* fo ae oval is [BNA]. a. prseputia'lis, the line of junction of skin and mucous membrane at the anterior extremity of the prepuce a. trache'se, one of the cartilaginous rings of the trachea, a. tend in'eus commu'nis [BNA], ligament of Zinn. * a. tympan'icus, tympanic ring, a more or le complete bony ring at the inner end of the external auditory meatus, giving attachment to the drum membrane. a. umbilical is, umbilical ring, an opening in the line a alba through which pa the umbilical ve els in the fetus; it is at first near the pubis, but gradually ascends to the center of the abdomen; it is closed in the adult, its site being indicated by the umbilicus or navel, a. urethra'lis, a thickening of the middle muscular coat of the bladder around the urethral opening, forming the sphincter vesicae muscle.