I052 A MANUAL OF ANATOMY 



found in the back part of the right auriculo-ventricular groove, and, it may 

 be, in the front part of it. The anterior cardiac veins wiU be found on 

 the front of the right ventricle and along the margo acutus, and they are 

 to be traced to the right coronary vein. The posterior cardiac veins will be 

 found on the inferior surface of the left ventricle, and they are to be followed 

 to the lower border of the coronary sinus. The oblique vein of Marshall is 

 to be carefully looked for on the back of the left auricle, along which it passes 

 downwards and inwards to open into the left extremity of the coronary 

 sinus. The tributaries of this sinus are now to be fully reviewed, and there- 

 after it is to be laid open with scissors. This will bring into view a valve, 

 composed of two segments, which is situated at the place where the great 

 cardiac or coronary vein opens into the sinus, namely, about i inch from 

 the ending of the sinus in the right auricle. 



The very delicate nerves derived from the coronary plexuses course upon 

 the surfaces of the ventricles, but in the human heart they do not lend them- 

 selves very readily to inspection. The heart of the calf is much more 

 favourably disposed for their examination. 



Interior of the Heart. — In this dissection the best way to proceed is to 

 follow the course of the blood through the heart. The right auricle is to be 

 laid open by two incisions as follows : (i) a vertical incision is to be made 

 from the auricular extremity of the superior vena cava to near the point of 

 entrance of the inferior vena cava, keeping clearly in front and to the left 

 of it, in order not to injure the vestigial Eustachian valve which is associated 

 with its orifice ; and (2) an oblique incision is to be made from the auricular 

 appendix to about the centre of the vertical incision. Having removed the 

 venous blood and sponged the interior of the auricle, the following points are 

 to receive attention : (i) the musculi pectinati, situated on the wall of the 

 auricular appendix and the adja:cent portion of the right wall of the atrium ; 

 (2) the crista terminalis ; (3) the fossa ovalis and annulus ovalis on the inter- 

 auricular septum ; (4) the so-called tubercle of Lower ; (5) the vestigial 

 Eustachian valve in connection with the orifice of the inferior vena cava ; 

 (6) the opening of the coronary sinus, and the Thebesian valve ; (7) the fora- 

 mina Thebesii ; and (8) the auriculo-ventricular orifice. It is to be noted 

 that no valve guards the opening of the superior vena cava. 



In connection with the annulus ovalis a very minute opening may be found 

 under cover of it, leading into the left ventricle. Its possible presence may 

 be determined by exploring with a fine probe. Three fingers, held side by 

 side, should be passed through the auriculo-ventricular orifice, and, if normal, 

 it will be found to admit them readily. 



The right ventricle is to be opened by means of two incisions, the left fore- 

 finger having previously been passed through the auriculo-ventricular orifice. 

 A transverse incision is to be carried along the upper part of the ventricle, 

 just below and parallel to the auriculo-ventricular groove. This incision is 

 to be prolonged as far as a point below the root of the pulmonary artery. 

 The other incision is to commence at the left end of the foregoing incision, 

 and is to be carried downwards just to the right of the antero-superior inter- 

 ventricular groove. In this manner a triangular flap, representing the front 

 wall of the right ventricle, can be turned down, and the cavity fully exposed. 

 The second incision, just stated, may be replaced by one extending along 

 the margo acutus to the lower end of the antero-superior interventricular 

 groove, and then a triangular flap would be raised towards the left. 



After cleansing the ventricle, the dissector is to observe (i) that its cavity is 

 excluded from the apex of the heart, (2) that it is prolonged to the root of 

 the pulmonary artery as the infundibulum or conus arteriosus, and (3) that the 

 interventricular septum bulges into it, so as to be convex on its right aspect. 

 The fleshy elevations, called columnae carneae, are to receive attention, their 

 various kinds are to be noted, and special attention is to be given to the 

 variety known as the musculi papillares. These latter will be found to be 

 disposed in two groups — anterior and posterior. The absence of columnae 

 carneae from the infundibulum is to be noted, and the moderator band is to 

 be looked for extending from the anterior papillary muscle to the interven- 



