242. The ŒSOPHAGUS is a large membranous tube that extends behind the trachea, the heart, and lungs, pierces the diaphragm, and terminates in the stomach. It is composed of two membranes—an internal, or mucous, and a muscular coat. The latter is composed of two sets of fibres; one extends lengthwise, the other is arranged in circular bands.
243. The STOMACH is situated in the left side of the abdomen, immediately below and in contact with the diaphragm. It has two openings; one connected with the œsophagus, called the car´di-ac orifice; the other connected with the upper portion of the small intestine, called the py-lor´ic orifice. It is composed of three coats, or membranes. The exterior or serous coat is very tough and strong, and invests every part of this important organ. The middle, or muscular coat is composed of two layers of muscular fibres, one set of which is arranged longitudinally, the other circularly. The interior coat is called the mucous, and is arranged in ru´gæ, (folds.) The stomach is provided with a multitude of small glands, in which is secreted the gastric fluid.
Illustration. The three coats of the stomach anatomically resemble tripe, which is a preparation of the largest stomach of the cow or ox. The outer coat is smooth and highly polished. The middle coat is composed of minute threads, which are 117 arranged in two layers. The fibres of these layers cross each other. The inner coat is soft, and presents many folds, usually named “the honey-comb.”
241. Describe the pharynx and the passages leading from it. 242. Give the structure of the œsophagus. 243. Where is the stomach situated? How many coats has it? Describe them. What article prepared for food does the stomach resemble?
Fig. 60.
Fig. 60. The inner surface of the stomach and duodenum. 1, The lower portion of the œsophagus. 2, The opening through which the food is passed into the stomach. 8, The stomach. 9, The opening through which the food passes out of the stomach into the duodenum, or upper portion of the small intestine. 10, 11, 14, The duodenum 12, 13, Ducts through which the bile and pancreatic fluid pass into it. a, b, c, The three coats of the stomach.
244. The INTESTINES, or alimentary canal, are divided into two parts—the small and large. The small intestine is about twenty-five feet in length, and is divided into three portions, namely, the Du-o-de´num, the Je-ju´num, and the Il´e-um. The large intestine is about five feet in length, and is divided into three parts, namely, the Cæ´cum, the Co´lon, and the Rec´tum. ([Appendix D.])
245. The DUODENUM is somewhat larger than the rest of the small intestine, and has received its name from being in 118 length about the breadth of twelve fingers. It commences at the pylorus, and ascends obliquely backward to the under surface of the liver. It then descends perpendicularly in front of the right kidney, and passes transversely across the lower portion of the spinal column, behind the colon, and terminates in the jejunum. The ducts from the liver and pancreas open into the perpendicular portion, about six inches from the stomach.