Pharynx

The pharynx in frog is very short. Thus it is included in the the buccopharyngeal cavity. The pharynx opens in the oesophagus. The oesophagus is relatively short and wide. There being several longitudinal folds of the inner lining, the oesophagus can be much widened when necessary. Posteriorly, the oesophagus communicates with the stomach. The anterior wider part of the stomach is called cardiac stomach while the posterior, narrow, muscular part bent slightly towards the right is called pyloric stomach. The pyloric stomach opens in the duodenum through the opening guarded by sphincter muscles that form pyloric valve and keeps the opening closed. The stomach can be distended greatly because of several longitudinal folds therein. Duodenum is the first part of the small intestine and measures about 3-4cm. The longer part of the small intestine behind the duodenum is called ileum which opens posteriorly in the rectum which is thin-walled and about 3-5 cm. long. The rectum opens, into the cloca in which the ureters or urinogenital duct, oviducts and urinary bladder open. The cloaca opens to the outside at the posterior end of the body through a cloacal aperture which is guarded by sphincter muscles. An accessory digestive gland-Pancreas- is located in the mesentery in the more or less ‘U’ shaped loop formed between the stomach and duodenum. The pancreas is a yellowish, irregular gland. Ventral to the stomach and slightly on the left side there is a large, dark reddish brown liver. It is the largest gland of the body. It has two lobes of which the left one is larger and subdivided into two lobes. Thus, the liver appears to be trilobed. Near the median small lobe of the liver there is a small spherical, greenish blue gall bladder that stores bile secreted by liver cells. A large hepatic duct opens in the gall bladder. A cystic duct arises from the gall bladder and passes through the pancreas, receiving several pancreatic ducts and finally opens in the duodenum as a common bile duct.