DISSECTION OF THE PIG EMBRYO 43 



lungs? From the anterior part of the arch of the aorta 

 arises a vessel which carries the blood toward the head. 

 This vessel is the innominate artery. Branches from the 

 innominate artery are given off laterally, going to each 

 fore-limb, the right and left subclavian arteries. Do you 

 find the carotid arteries leading from the innominate 

 artery to either side of the head? Trace the inferior 

 Vena cava vein to the heart. With what part of the 

 heart does it connect? The superior vena cava and the 

 inferior vena cava empty into the heart near the same 

 place. The blood from the anterior part of the body is 

 collected in the superior vena cava. Trace it and its 

 branches to the neck and fore-legs. Do you find the 

 pulmonary veins? The pulmonary veins carry the 

 blood from the lungs to the heart. What part of the 

 heart? Open the heart. Describe the valves separating 

 the auricles from the ventricles. The two ventricles are 

 separated by a muscular wall, the ventricular septum. 

 The two auricles are not separated. The opening be- 

 tween the two auricles is the foramen ovale. Is there any 

 trace of the formation of the auricular septum? 



Draw a diagram of the circulatory system in the thorax 

 as you have found it in your dissection. Label all the 

 parts. 



Trace the lungs to the mouth. Trace the oesophagus 

 to the mouth. What is the relation of the oesophagus 

 to the trachea and larynx? 



