THORACIC DUCT AND HEART. 359 



h. The common iliac arteries, formed by the apparent 

 bifurcation of the aorta, run backwards and out- 

 wards to the hind-limbs, along which they are 

 continued as the femoral arteries. In the abdo- 

 men each gives off the following branches : 



i. The ilio-lumbar artery runs outwards along 

 the posterior part of the dorsal wall of the 

 abdomen. 



ii. The internal iliac artery runs backwards along 

 the dorsal wall of the pelvic cavity. 



iii. The vesical artery is a small branch which runs 

 backwards to the bladder. In the female it 

 also supplies the uterus. 



4. The pulmonary artery has already been described 

 (p. 350). 

 Follow the branches of the pulmonary artery into the lungs. 

 Draw the arteries, first sketching the outline and chief viscera. 



D. The Thoracic Ducts. * 



The thoracic ducts are a pair of thin-walled tubes running 

 forwards through the thorax, and lying in the fat to the 

 side of and dorsal to the aorta. Between the third arid 

 fourth ribs they expand somewhat, and then turning inwards 

 traverse the thymus and open into the anterior vena cava 

 close to the subclavian vein. 



The thoracic ducts receive lymphatic vessels from almost 

 all parts of the body, and place these in communication 

 with the venous system. 



E. Dissection of the Heart. 



Do not remove the heart until after the dissection of the nerves 

 of the neck is completed (see pp. 373 and 375). Cut across the 

 great vessels, about half an inch from the heart. Remove the 

 heart, and pin it down under water with the dorsal surface 

 upwards, passing the pins through the ventricles and the arch 

 of the aorta. Clean the roots of the several vessels. 



