veine

vaginal and capsular veins, and subdividing form interlobular veinsb (Fig. 88), which send branches to interior of each lobule forming a plexus converging to empty into the central intra-lobular v running at right angles to other vessels; the intra-lobular vein empties into a sublobular vein, a radicle of hepatic vein; the

Hepatic veins16 (Fig. 87) commence in sublobular veins as just described, which unite to form three large and several smaller branches terminating in inferior vena cava in fissure for that vessel; the

FIG. 88.

Glisson-vaginal, supplying nutriment to vessels, ducts, etc., capsular to terminate in external fibrous coat-and ends in a plexus on outer surface of each lobule formed by ultimate branches of portal vein, the interlobular plexus above described; the

Hepatic duct above 13 is formed by the union of two trunks of nearly equal size which emerge from the transverse fissure, one from the right and other from left lobe; it passes downward to the right for one inch and a half to be joined by the cystic duct from the gall-bladder, to form the ductus communis choledochus (see p. 238); the

Lymphatics accompany blood vessels, and consist of a deep and superficial set.

Whence do the nerves of the liver come?

From the hepatic plexus of the sympathetic, from the pneumogastric nerves, especially the left, and right phrenic.

Describe the liver structure.

It is composed of numerous lobules from one-twentieth to onetenth of an inch in diameter, of irregular form in human liver, polygonal in pigs, their bases clustered round the sublobular vein, to which each is connected by its intralobular vein; the lobules are bound together by loose areolar tissue; each lobule is formed of hepatic cells, spheroidal or many-sided nucleolo-nucleated cells, measuring from one-one thousandth to one-two thousandths of an inch, containing granular yellow coloring matter and globules, which cells lie in the meshes of the dense capillary network occupying its interior, spaces between the cells forming intercellular biliary passages, the radicles of the bile ducts.

What is the capsule of Glisson?

The areolar tissue entering the transverse fissure, surrounding the hepatic vessels to their ultimate ramifications, and continuous with fibrous coat of organ.

How may the portal be distinguished from the hepatic veins in a liver section?

The portal veins are collapsed, being surrounded by the capsule of Glisson, while the hepatic are patulous, being closely connected with liver substance.

Describe the gall-bladder1.

It is a pear-shaped, fibro-muscular receptacle for the bile; its fundus and under surface of body and neck covered by peritoneum, while its interior is lined with a cylindrical-celled, epithelialcoated mucous membrane, presenting a honeycombed appearance from the confluence of numerous minute rugæ; its length is from three to four inches, its capacity from eight to twelve fluidrachms, and it lies in a fissure on the under surface of liver, its fundus— most dilated portion-projecting slightly beyond the anterior border, touching abdominal wall just below ninth costal cartilage; the narrow neck curves upon itself like an italic f, to terminate in the cystic duct, which is about one inch long, and is lined by mucous membrane so disposed in a series of crescentic folds as to present the appearance of a spiral valve; it joins the hepatic duct to form the common bile-duct.

Describe the ductus communis choledochus13 (Fig. 87).

It is about three inches long, three-sixteenths of an inch in diameter, and is formed by the junction of the hepatic and cystic ducts; it opens usually by a common orifice with the pancreatic duct, a little below the middle of inner side of descending portion of duodenum; its walls are composed of fibrous with a little muscular tissue, its mucous membrane is covered with columnar epithelium, and it runs between the layers of gastro-hepatic process of the peritoneum.

The Pancreas.

Describe the pancreas (Fig. 85).

It is a compound racemose gland, from six to eight inches long, by one and one-half inches at its widest part, lying behind the stomach and in front of the first lumbar vertebra. It is composed of lobules connected by areolar tissue, each lobule consisting of an ultimate branch of the duct lined with columnar epithelium, terminating in cæcal pouches or acini, also lined with cylindrical epithelium, outside of which is a fine capillary network. The

Pancreatic duct (canal of Wirsung) extends the whole length of

gland and opens into middle of descending part of duodenum, to the inner side, with common bile-duct; its

Head or right extremity is embraced by the concavity of the duodenum, the common bile-duct lying behind, the pancreaticoduodenal artery in front; the

Tail or left extremity reaches spleen above left kidney and suprarenal body; the

Body is covered by the ascending layer of transverse meso-colon and posterior surface of stomach; posteriorly, the superior mesenteric artery and vein, the portal vein, the vena cava, and the aorta separate it from the first lumbar vertebra.

The arteries18 (Fig. 85) are derived from the splenic, pancreatico duodenal branch of hepatic and superior mesenteric arteries.

The veins empty into splenic and superior mesenteric veins. The nerves come from the splenic plexus of the sympathetic.

What is the lesser pancreas?

A lobular fold, passing transversely to the left behind the superior mesenteric vessels, which is sometimes detached from the gland when it may open into duodenum by a separate duct an inch or more above the pancreatic duct.

The Ductless Glands.

What are the ductless glands?

The spleen, suprarenal capsules, thyroid and thymus glands, bodies whose functions are uncertain and which have no ducts. The spleen and suprarenal capsules lie in the abdominal cavity, but the others will be for convenience described after them.

Describe it.

10

The Spleen (Fig. 85).

It is a soft, brittle, very vascular, oblong, flattened organ embracing the cardiac end of the stomach, to which it is attached by the gastro-splenic fold of peritoneum, which latter membrane completely invests the spleen, except where the gastro-splenic

omentum and suspensory ligament are attached; the organ lies deeply in the left hypochondriac region; the

Outer surface is convex, smooth, lying in contact with diaphragm, which separates it from the ninth, tenth, and eleventh ribs; the Inner surface is concave, lies in contact with stomach, and presents the

Hilum, a vertical fissure pierced at various points by blood vessels, lymphatics, and nerves; the

Anterior border is often notched, and the

Posterior border is rounded and in relation with left kidney; the Suspensory ligament, a peritoneal fold, connects it with the under surface of diaphragm; the

Fibro-elastic coat, beneath the serous (see above) which intimately adheres to it, forms the framework of the spleen, passing inward at the hilum with the vessels as sheaths, from which, and the inner surface of capsule, numerous bands or trabeculæ pass, uniting to form numerous small spaces or areola filled with the splenic pulp.

Describe the spleen-pulp.

It is of a dark reddish-brown color, and under the microscope is seen to consist of a network of branched connective-tissue cells, containing pigment granules (broken-down blood corpuscles), granular matter, nucleated cells, free nuclei, and red blood-cells in all stages of disintegration; the

Splenic artery20 (Fig. 85) is large, tortuous, and divides at hilum into five or six branches which do not anastomose to any extent, each branch breaking up again and again into smaller ones, until they terminate in bundles of straight vessels which open into the interstices of the reticulum formed by the branched connective-tissue cells.

What are the Malpighian bodies?

Small, rounded, expanded masses of the lymphoid tissue of the external coat of the small splenic arteries, from one-one hundredth to one twenty-fifth of an inch in diameter, usually surrounding the vessel, but sometimes projecting from one side; they are composed of a delicate reticulum packed with lymph corpuscles and pervaded by capillaries; the