418 LABORATORY MANUAL OF HUMAN ANATOMY 



What is the relation of this to the ductus arteriosus 

 [Botalli] of foetal life? (Fig. 211.) 

 (/) Arterial orifice of right ventricle (ostium arteriosum ventriculi dextri) 



(0. T. pulmonary orifice). 



(fa] Semilunar valves of pulmonary artery (valvulae semilunares 

 A. pulmonalis). 



(faa) Anterior semilunar valve (valvula semilunaris an- 



terior}. 



(fab) Right semilunar valve (valvula semilunaris dextra). 



(fac) Left semilunar valve (valvula semilunaris sinistra). 



FIG. 211. 



Aorta descendens 

 Ductus arteriosus 



A. pulmonalis 



Heart of a foetus of 7 months. {. (From Gegenbaur, Lehrb. der Anat. des Mensch., Leipzig, 

 1899, 7 Aufl., Bd. ii. p. 232, Fig. 521.) 



Slit open the pulmonary artery between the anterior and 

 right semilunar valves. Examine the nodules of the semilunar 

 valves (noduli valvularum semilunarium) and the so-called 

 " sails" of the valves (lunulae valvularum semilunarium). 



Pulmonary Veins and Left Atrium. 



The pulmonary veins (Vv. pulmonales) may again be exam- 

 ined. Note the differences in the relations of the right pulmo- 

 nary veins (Vv. pulmonales dextrae) and the left pulmonary 

 veins (Vv. pulmonales sinistrae). 



Cut through the vena cava inferior and turn the heart 

 upward. Observe the entrance of the venae pulmonales into the 

 left atrium. 



The left atrium (atrium sinistrum) (0. T. left auricle) may 

 next be examined. Note the size, shape, and position of its 

 auricle (auricula sinistra) (0. T. left auricular appendix). 



Turn the heart well to the right, with the apex forward. 

 Make an oblique cut, from the middle of the posterior margin of 

 the atrium behind, forward to the tip of the auricula sinistra. 



