Fig. 119. Anterior Thoracic Wall and Heart in the Adult. 



hi addition to the soft parts covering the Thorax, the jrd, 4th, ^th Costal 



Cartilages and the junction of the last named ivith the 6th Costal Cartilage 



together with the Intercostal muscles lun'e been removed. 



Between the slips of the Triangularis Sterni Muscle the parietal pleura 

 (blue) is visible ; its lines of reflection behind the Sternum are also delineated in blue. 



Between the 3rd and 4th Costal Cartilages (cf. Pig. 116) the right and 

 left pleurae are in contact with each other, as in the adult the Th3'mus has con- 

 tracted upwards. The right pleura ma}' extend considerably beyond the middle 

 line, often as far as the left border of the Sternum. 



Parallel with the borders of the Sternum, at a distance which varies with 

 the width of the bone, the Internal Mammary Artery, a branch of the Subclavian, 

 takes its course accompanied b)' 2 Venae Comites except in the two upper inter- 

 costal spaces where there is only one vein. Around the artery lie lymphatic 

 glands, (Sternal and Anterior Mediastinal Glands) more numerous above than 

 below. The Heart in the Adult is more deepl}' situated than in the Newborn 

 and its apex is further to the left. 



The distance from the Apex (Left \'^cntricle) to the nipple is 2'^l^ths to 

 iVsthsinch in the vertical line, and Vjths to if/jth inch in the horizontal direction. 

 (As the Figure is ''/jths nat. size, actual measurements according to the Figure 

 will require multiplication by five thirds.) 



^\n irregularity in the Costal Cartilage which may even in\olve the rib 

 is shewn in the 4th Costal Cartilage on the right side. 



The following data connected with the bony Thorax and in particular 

 the costal cartilages have been made out by Bardelebex. 



In about 10 "/o the Sth Costal Cartilage, on both sides, articulates with 

 the Sternum. The 6th and 7th Costal Cartilages usually articulate with each 

 other ; in 60 % on the left side and in 40 "/o on the right side, articulations exist 

 between the 5th and 6th Costal Cartilages. The arrangement, together with the 

 close apposition of the cartilages, convert the intercostal spaces in front of the 

 pericardium into narrow slits. 



The position of the Apex of the Heart, the Pulmonar}' and Aortic Valves 

 is not absolutely constant — quite apart from physiological \ariations in form 

 and position of the Heart. 



The Pulmonary Valves usually lie opposite the 2nd left interspace or 

 behind the 3rd left costal cartilage, rarely in the 3rd interspace. 



For operations upon the Pericardium the most suitable site is a small 

 area where the pericardium is uncovered by pleura. The entrance may be made 

 through the 4th or 5th intercostal space, close to the Sternum, without wounding 

 the pleura; the Internal Mammar}' Artery must always be borne in mind. 

 Removal of a part of the 4th and 5th Costal Cartilages with a small portion of 

 the left Sternum, allows a fair extent of the pericardium to be exposed. 



