trigo'num, pi. trigo'na

[L. from G. irigonon, a triangle.] Trigone, any triangular area. t. acus'- tic i, trigone of the acoustic nerve, a prominence on the outer side of the fovea inferior of the floor of the fourth ventricle, below the striae meduUares. t. carot'icum, the superior carotid triangle,* or triangle of election, t. cerebra'le, fornix (i). t. cervica'le, t. coll i, t. col later a'le [BNA], collateral trigone, t., ventriculi, an approximately triangular space in the pars central is of the lateral ventricle of the brain, between the posterior and descending horns, t. coll i, any one of the triangles of the neck, more especially t. caroticum. t. deltoid'eopectora'le [BNA], Mohrenheim's fo a, a space between the pectoral is major and deltoid muscles, below the clavicle, t. dorsa'Ie, t. du'rum, the space between the nates, or coUiculi super i ores [BNA], of the quadrigeminal bodies, t. femora'le [BNA], Scarpa's triangle, a, triangular space at the upper and inner part of the thigh, bounded by the sartorius and adductor long us muscles and the inguinal (Poupart's) ligament, fibro's um [BNA], one of two cartilaginous nodules, to the right and left of the root of the aorta, forming the extremities of the incomplete fibrous ring which surrounds the left atrioventriculai^ orifice, t. fluc'tuans, commis sur a posterior cerebri, t. haben'alee [BNA], trigone of the habenula, a small triangular area between the habenula and the thalamus, immediately anterior to the superior quadrigeminal body on either side. t. hypoglas'si, t. nervi hypo glo i. t. inguina'le, (i) a triangular space above and external to the pubic spine, formed by the outer edge of the rectus abdominis' muscle and the inguinal furrow; (2) t. femorale. t. lemnis'ci [BNA], triangle of Reil, triangle or trigone of the fillet, a triangular area on the upper part of the outer side of the brachium* conjunct i vum. lumba'le [BNA], Petit's lumbar triangle, an interval bounded by the edges of the lat is sim us dors i and obliquus extern us muscles and the crest of the ilium, t. ner'vi hypoglos'si [BNA], trigone of the hypoglo al nerve, a slight elevation in the fovea inferior of the fourth ventricle, beneath which is the nucleus of origin of the 12th cranial nerve, t. olfacto'rium [BNA], olfactory trigone, a grayish triangular area forming the posterior extremity of the olfactory tract where it diverges into the three roots, or olfactory strise; the trigone lies just above the optic nerve near the chiasm, t. omoclavicula'TC [BNA], subclavian triangle, a triangle bounded by the clavicle, the omohyoid muscle, and the sternocleidomastoid muscle, t. pal a'tl, palatal triangle.* t. pen'- sile, t. fluctuans. t. sternocosta'le, a muscular defect in the diaphragm between the costal and the sternal portions, t. urogenita'le, diaphragm a nerve, ala* oinerea [BNA], vagina'le, Paw-