The stomach is the principal organ of digestion. Out of the nutriment
taken into it all the tissues of the body are renewed. It lies under the
diaphragm, and is held in place by the abdominal muscles. The stomach is
moved during respiration, descending with every inspiration, and rising
with every expiration.
In addition to this exercise during the production of tone, the stomach
is held firmly between the diaphragm and abdominal muscles. At the close
of the tone the muscles which thus hold the stomach relax.
[Illustration: A view of the Organs of Digestion, opened in nearly their
whole length; a portion of the œsophagus has been removed on account of
want of space in the figure; the arrows indicate the course of
substances along the canal: 1, the upper lip, turned off the mouth; 2,
its frænum; 3, the lower lip, turned down; 4, its frænum; 5, 5, inside
of the cheeks, covered by the lining membrane of the mouth; 6, points to
the opening of the duct of Steno; 7, roof of the mouth; 8, lateral
half-arches; 9, points to the tonsil; 10, velum pendulum palati; 11,
surface of the tongue; 12, papillæ near its point; 13, a portion of the
trachea; 14, the œsophagus; 15, its internal surface; 16, inside of the
stomach; 17, its greater extremity or great cul-de-sac; 18, its lesser
extremity or smaller cul-de-sac; 19, its lesser curvature; 20, its
greater curvature; 21, the cardiac orifice; 22, the pyloric orifice; 23,
upper portion of duodenum; 24, 25, the remainder of the duodenum; 26,
its valvulæ conniventes; 27, the gall-bladder; 28, the cystic duct; 29,
division of hepatic ducts in the liver; 30, hepatic duct; 31, ductus
communis choledochus; 32, its opening into the duodenum; 33, ductus
Wirsungii, or pancreatic duct; 34, its opening into the duodenum; 35,
upper part of jejunum; 36, the ileum; 37, some of the valvulæ
conniventes; 38, lower extremity of the ileum; 39, ileo-colic valve; 40,
41, cœcum, or caput coli; 42, appendicula vermiformis; 43, 44, ascending
colon; 45, transverse colon; 46, 47, descending colon; 48, sigmoid
flexure of the colon; 49, upper portion of the rectum; 50, its lower
extremity; 51, portion of the levator-ani muscle; 52, the anus.]
[Illustration: LIVER. The inferior or concave surface of the liver,
showing its subdivisions into lobes: 1, center of the right lobe; 2,
center of the left lobe; 3, its anterior, inferior, or thin margin; 4,
its posterior, thick, or diaphragmatic portion; 5, the right extremity;
6, the left extremity; 7, the notch in the anterior margin; 8, the
umbilical or longitudinal fissure; 9, the round ligament or remains of
the umbilical vein; 10, the portion of the suspensory ligament in
connection with the round ligament; 11, pons hepatis, or band of liver
across the umbilical fissure; 12, posterior end of longitudinal fissure;
13, 14, attachment of the obliterated ductus venosus to the ascending
vena cava; 15, transverse fissure; 16, section of the hepatic duct; 17,
hepatic artery; 18, its branches; 19, vena portarum; 20, its sinus, or
division into right and left branches; 21, fibrous remains of the ductus
venosus; 22, gall-bladder; 23, its neck; 24, lobulus quartus; 25,
lobulus Spigelii; 26, lobulus caudatus; 27, inferior vena cava; 28,
curvature of liver to fit the ascending colon; 29, depression to fit the
right kidney; 30, upper portion of its right concave surface over the
renal capsule; 31, portion of liver uncovered by the peritoneum; 32,
inferior edge of the coronary ligament in the liver; 33, depression made
by the vertebral column.]