52 LABORATORY DIRECTIONS 



small swelling, the ampulla of Fater, into which the pancreatic 

 duct and the common bile duct empty. The common bile duct 

 (ductus choledochus) is formed by the union of three bile ducts: 

 two hepatic ducts, one from each side of the liver, and the cystic 

 duct from the gall bladder. 



Pancreas. — This is a flattened irregular gland, consisting 

 of two lobes, one lying along the duodenum and the other in the 

 great omentum near the greater curvature of the stomach. 

 Do not confuse it with the large lymph glands which lie in the 

 mesenteries. The main pancreatic duct (duct of Wirsung) is 

 short and wide and opens, with the common bile duct, into the 

 ampulla of Vater in the duodenum. The pancreatic duct is 

 formed by two branches, one from each lobe of the pancreas. 

 To find the pancreatic ducts, begin near the ampulla of Vater 

 and scrape off the surface tissue of the pancreas until a white 

 duct appears, then trace this both ways. 



Slit open the duodenum and find the opening of the ampulla 

 of Vater on the inside. 



Lungs. — Trace the trachea back into the chest cavity and 

 find where it divides into two bronchi, one going into each lung. 

 Work around the blood vessels so as not to injure them. The 

 lungs are paired, many lobed organs. The right and left lungs 

 are completely separated, each lying in its own half of the thorax, 

 with a double septum, the mediastinum, between them. The 

 right lung is slightly larger and is divided into three smaller 

 proximal lobes and a large distal one. The left lung is divided 

 into three main lobes. Trace one of the bronchi as far as possible 

 into its lung. Within the lung it will be found to break up into 

 many branches, the bronchioles. Are the bronchioles supported 

 by cartilaginous rings ? 



Thymus Gland. — This lies just anterior to the heart on the 

 ventral side of the trachea. Superficially it may resemble fatty 

 tissue. In adult cats it is usually degenerate, but may be easily 

 seen. The thymus is not part of the respiratory system. 



Diaphragm. — This muscular partition between thorax and 

 abdomen is to be considered as an organ of respiration. It is an 

 arched muscular structure with the muscle fibers originating 

 from the body wall, vertebrae, and ribs and converging on a 

 central tendon in the middle of the diaphragm for their insertion. 



