RELATION OF HEART TO CI I EST- WALLS lliy 



oilier forei<rii Ixxly, loose in the ])U'ural sac and rolling on the diaphragm, might 

 fall to the lowest part of the sac, which would he between the eleventh and twelfth 

 rihs. The ball might be extracted here. The chest might also be tai)ped here, but 

 not with a trocar, since a trocar would j>enetrate both layers of jtleura and go 

 through the diaphragm into the abdomen. The operation should l)e done cautiously 

 by an incision beginning about two inches from the sjjine, on the outer border of 

 the erector s))in8e, on a level lietween the spines of the eleventh and twelfth thoracic- 

 vertebriv. The intercostal artery will not be injured if the opening be made below 

 the middle of the s)»;iee, wliieli is v<'rv wide.' 



Outline of the heart. Its relation to the chest-wall. — The upi)er limit of 

 the heart (base) will be defined l»y a line crossing the sternum a little above the 

 upper border of the third costal cartilage, reaching about half an inch to the right 

 and al)out one inch to the left. Its apex corres])onds to a point in the fifth space, 

 about two inches below the male left nipple, and an inch to tlie inner side. This 

 point will be about three inches from the left border of the sternum. The right 

 border (right auricle) will be given by a line, slightly convex outwards, drawn 

 from the right extremity of the upjier border to the right seventh chondro-sternal 

 joint. If another line, similarly slightly convex, be drawn onwards from this jjoint 

 across the last piece of the sternum, just above the xiphoid cartilage, to the apex, 

 it will give the lower border (right ventricle), which rests on the central tendon of 

 the diaphragm. The left border (left ventricle) will be given by a line, convex to 

 the left. i»assing from the left extremity of the upper border to the apex, well insid*- 

 the nipple line. This line should be three inches from the middle of the sternum 

 at the level of the fourth costal cartilage. 



If a circle two inches in diameter be described around a point midway between 

 the left nipple and the lower end of the gladiolus, it Avill define with sufficient 

 accuracy for practical purposes that part of the heart which lies innnediately 

 behind the chest wall, and which is uncovered by lung or pleura (Latham). 



The valves. — The pulmonary valves (the most superficial) lie, in front of 

 the aortic, bi-hind the left clKMidro-stenial joint, and opposite to the U])per border 

 of the third costal cartilage. The aortic valves lie behind and a little below 

 these, opposite to the inner end of the third intercostal space, and on a level with 

 the lower border of the third costal cartilage. The auriculo-ventricular open- 

 ings lie at a somewhat lower level than that of the aortic and i)ulmonary. Thus 

 the tricuspid valves lie behind the sternum at the level of the fourth intercostal 

 space; and the mitral valves, the most deeply placed of all, lie a little to the left 

 of these, behind the left edge of the sternum and the fourth left costal cartilage. 



' Thus these valves are so situated that the mouth of an ordinary-sized stetho- 

 scope will cover a portion of them all, if placed over the juncture of the third 

 intercostal space, on the left side, with the sternum. All are covered by a thin 

 layer of lung; tlierefore we hear their action better when the breathing is for a 

 nKjment suspended ' ( IIolden\ 



Relation of vessels to the wall of the thorax. — Aortic arch, — The 

 ascending part reaches from a spot behind the sternum, a little to the left of the 

 centre, on a level with the third left costal cartilage, to the upper border of the 

 second right cartilage; thus it passes upwards, backwards, and to the right, and is 

 about two inches long. The transverse part then crosses to the left behind the 

 sternum (the highest part of the arch being about an inch l)elow the notch), 

 reaching from the second right costal cartilage to the lower border of the fourth 

 thoracic vertebra on the left side. This ])art recedes from the surface, and, with 

 the next, cannot be marked out on the surface. The third, or descending i)art, the 

 shortest of the three, reaches from the lower border of the fourth to that of the 

 fifth thoracic vertebra. 



Innominate artery. — A line drawn fnjm the toj) of the arch, aliout an inch 

 below the sternal notch, and a little to the right of the centre, to the right sterno- 

 clavicular joint, will irive the line of this vessel. 



Left common carotid. — This vessel will be denoted by a line somewhat sim- 

 ilar to the al)ove. jiassing from the level of tlie arch a little to the left of the last 

 starting point to the left .sterno-clavicular joint. 



Left subclavian artery. — A line from the end of the transverse arch, behind 



