TRIAMYLAMIN 



1539 



TRIANGLE 



ylamin [tri-am-W -am-iti) [tres, three; amy/, 

 imin], X, C 5 H,,). V Tertiary amin of amyl. 

 iamylin \tri-am'-il-in) [tres, three; amy/'], C 3 H 5 - 

 A compound produced by heating amyl- 

 ilcohul and acrolein with acetic acid. 

 1 iamylphosphin (tri-am-il-fos / -fin). A compound 

 vith the formula (C 5 H n ) 3 P. 

 'iandrous {tri-an' -drus) [rpelc, three ; avrjp, a male]. 



logy, having three stamens, 

 'iangle [tri f -ang-gl) [tres, three; angulus, angle]. 

 V space bounded by three lines or sides and with 

 ' hree corners or angles. T. of Assegat. a triangle 

 ormed by lines uniting the projection of the nasion on 

 he alveolo-condylar plane and the alveolar and nasal 

 . oints and one uniting the two latter. T. of Bryant. 

 *e T., Iliofemoral. T., Carotid, Inferior (" Tri- 

 ngle of necessity '"), located in the neck ; it is bounded 

 entrad by the median line of the neck, dorsad by the 

 entral margin of the sterno-mastoid, and cephalad by 

 le ventral belly of the omo-hyoid. Its floor is formed by 

 le longus colli below and the scalenus anticus above, 

 lie common carotid artery, internal jugular vein, 

 agus nerve, superficialis colli nerve, a branch of the 

 ommunicans noni, the inferior thyreoid artery, the 

 ^current laryngeal nerve, the sympathetic nerve, the 

 achea, thyreoid gland, and larynx are the important 

 nurtures within it. T., Carotid, Superior (" Triangle 

 f election"), located in the neck; it is bounded dor- 

 id by the sterno-mastoid, ventrad by the ventral belly 

 f the omohyoid, and cephalad by the dorsal belly of 

 ; ie digastric. Its floor is formed by the thyreo-hyoid, 

 I yo-glossus, and inferior and middle constrictors of the 

 The important structures contained within 

 e common carotid artery and its bifurcation 

 jito the external and internal carotids, the superior 

 liyreoid artery, the lingual artery, the facial artery, the 

 -cipitai and ascending laryngeal arteries, the internal 

 i gular vein and the veins corresponding to the arteries 

 |ientioned, the descendens noni, hypoglossal, pneumo- 

 utric. sympathetic, spinal accessory, superior laryn- 

 'al, and external laryngeal nerves. T., Cephalic, 

 triangle on the antero-posterior plane of the skull 

 funded by lines joining the occiput with the forehead 

 id with the chin and a line joining the latter two. 

 ., Digastric. See T. , Submaxillary. T. of Elbow, 

 triangle lying in front of the elbow with the base 

 rected upward toward the humerus, bounded ex- 

 : rnally by ttie supinator longus and internally by the 

 onator radii teres. Its floor is formed by the brachi- 

 :is anticus and supinator brevis. Its contents are the 

 achial artery and veins, the radial and ulnar arteries, 

 e median and musculo-spiral nerves, and the tendon 

 the biceps. T. of Election. See T., Carotid, Su- 

 T., Facial, a triangle formed by lines uniting 

 i with the alveolar and nasal points and a line 

 ning the latter two. T., Frontal, a triangle 

 unJed by the maximum frontal diameter and lines 

 ning its extremities and the glabella. T. of Hes- 

 lbach, a triangle at the lower part of the abdomen 

 unded laterad by the deep epigastric artery, caudad 

 Poupart's ligament, and mesad by the margin of 

 : rectus muscle. It is of importance in direct ingui- 

 1 hemia. T., Ilio-femoral, a triangle located at 

 - hip. Its hypothenuse is formed by Nelaton's line, a 

 le by the continuation outward of a line drawn 

 the two superior iliac spines, and the third by a 

 vn at right angles to this from the summit of the 

 ochanter. It contains the external abdominal 



• T., Inferior Occipital, a triangle having the 



1 diameter for its base and the inion for its 



• T., Infra-clavicular, a triangle situated below 

 : clavicle ; it is bounded above by the clavicle, below 



and to the inner side by the upper border of the great 

 pectoral muscle, and to the outer side by the anterior 

 border of the deltoid. It contains the axillary artery. 

 T., Inguinal. Same asT., Scarpa's, q. v. T. of Les- 

 ser, a triangle located in the neck. Its boundaries are as 

 follows : at its upper border the hypoglossal nerve ; the 

 two sides are formed by the ventral and dorsal bel- 

 lies of the digastric muscle. It is covered by the skin, 

 superficial and deep fasciae, and apex of the submaxillary 

 gland. The floor is formed by the hyo-glossus muscle. 

 It contains the ranine vein and hypoglossal nerve. T., 

 Lumbo-costo-abdominal, a triangle which is bounded 

 anteriorly by the external oblique, superiorly by the lower 

 border of the serratus posticus inferior and the point of 

 the 1 2th rib, posteriorly by the outer edge of the erector 

 spinae and inferiorly by the internal oblique. T., Man- 

 dibulo-condylar, a triangle having its apex at the 

 symphysion and its base between the two condyles. T., 

 Mandibulo-coronal, a triangle having its apex at the 

 symphysion and its base l^etween the two corona. T., 

 Mandibulo-gonial, a triangle having its apex at the 

 symphysion and its base between the two gonia. T., 

 Mento-ccndylar, a triangle formed by lines joining 

 the mental point to the condyles of the inferior maxilla 

 and these with each other. T., Mento-condylial, the 

 triangle of A. von TSrok having its base between the 

 condyles of the inferior maxilla and its apex at the gna- 

 thion. T., Mento-coronal, a triangle formed by lines 

 joining the mental point with each extremity of a line 

 joining the two corona. T., Mento-gonial, a tri- 

 angle of A. von Torok having the bigoniac diameter as 

 its base and the gnathion as its apex. T„ Mento- 

 mastoid, a triangle of A. von T5r5k with the bi-mas- 

 toid diameter as a base and the gnathion as an apex. 

 T., Mylo-hyoid, the three-cornered space bounded by 

 the mylo-hyoid and the two bellies of the digastric. 

 T. of Necessity. Same as T., Carotid, Inferior. 

 T. of the Neck, Anterior, a triangle bounded ventrad 

 by a line extending from the chin to the sternum, dor- 

 sad by the ventral margin of the sterno-mastoid, and 

 the base is formed by the lower border of the body of 

 the inferior maxilla and a continuation of this line to the 

 mastoid process of the temporal bone. It is covered by 

 the integument, the superficial and deep fasciae, and the 

 platysma myoides. It is subdivided into three smaller tri- 

 angles by the digastric muscle above and the ventral 

 belly of the omohyoid below. These are named from 

 below upward the inferior carotid, the superior carotid, 

 and the submaxillary, q. v. T. of the Neck, Pos- 

 terior, a triangle bounded ventrad by the sterno-mastoid 

 i muscle, dorsad by the ventral margin of the trapezius ; 

 the base is formed by the upper border of the clavicle. 

 The apex corresponds to the occiput. It is divided by 

 the dorsal belly of the omo-hyoid muscle into two 

 triangles, the occipital or upper, and the subclavian or 

 lower, q. v. T., Occipital, a triangle with the follow- 

 ing boundaries : ventrad, the sterno-mastoid muscle ; 

 dorsad, the trapezius, and caudad, the omohyoid muscle. 

 Its floor is made up of the splenius, the levator anguli 

 scapulae, and the middle and posterior scaleni. Its im- 

 portant contents are the spinal accessory nerve, the as- 

 cending and descending branches of the cervical plexus, 

 and the transversalis colli artery and vein. T., Omo- 

 clavicular. Same as 71, Subclavian, q. v. T., Omo- 

 hyoid. Same as T., Superior Carotid. T., Omo- 

 tracheal. See T., Carotid Inferior. T., Palatal, a 

 triangle of A. von Torok having the width of the palate 

 as its base and the alveolar point as its apex. T. of 

 Petit, an abdominal triangle bounded below by the crest 

 of the ilium and laterally by the external oblique and 

 latissimus dorsi. It is covered by the skin and fascia and 

 its floor is formed by the internal oblique. T., Pubo- 





