Part 134

FIG. 304.—ABDOMINAL VISCERA OF SHEEP, SUPERFICIAL VENTRAL VIEW. ]

The =stomach= is like that of the ox in its general arrangement. Its average capacity is about four gallons (ca. 15 liters). The =cardiac opening= is opposite the middle of the eighth intercostal space; it is just to the left of the median plane and about two to three inches (ca. 5 to 7 cm.) below the vertebral column. The ventral sac of the =rumen= is relatively larger and extends further to the right of the median plane than in the ox. There are no coronary pillars in the dorsal sac, but its upper part is papillated. The papillæ of the rumen are relatively =large= and somewhat tongue-like; the largest are about a fourth of an inch (ca. 6 mm.) in length. The =reticulum= is relatively larger than in the ox. Its ventral part curves more backward and less to the right than in the ox. The parietal surface extends forward as far as the sixth rib or intercostal space, and is related to the diaphragm and liver. The fundus lies on the sternal part of the diaphragm and in contact with the abomasum. The =œsophageal groove= is disposed much like that of the ox, and is about four to five inches (ca. 8 to 10 cm.) long. The =omasum= is much smaller than the reticulum, its capacity being only about one pint. It is oval and compressed laterally. It is situated almost entirely to the right of the median plane, opposite to the ninth and tenth ribs, higher than in the ox, and has no contact with the abdominal wall. It is related on the right to the liver and gall-bladder, on the left to the rumen, and below to the abomasum. The laminæ are less numerous than in the ox; in the neck which connects the omasum with the reticulum they have the form of low thick ridges, and bear long, pointed, horny papillæ. The =abomasum= is relatively larger and longer than in the ox. Its capacity is about twice that of the reticulum and averages about two quarts (ca. 1.75 to 2 liters). The blind anterior end lies almost centrally in the xiphoid region, in relation to the liver and reticulum. Its body extends backward a little below and almost parallel with the right costal arch. The pylorus is opposite the ventral end of the eleventh or twelfth intercostal space. The cells of the reticulum are much shallower than in the ox. At the reticulo-omasal opening and on the adjacent part of the laminæ of the omasum are large, pointed, horny papillæ. The number of laminæ is less than in the ox.

The general arrangement of the =intestine= is like that of the ox. The =small intestine= is about 80 feet (ca. 24 to 25 m.) long; its average diameter is about an inch (ca. 2 to 3 cm.), the caliber increasing in its terminal part, where a very extensive Peyer’s patch is found. The =cæcum= is about 10 to 12 inches (ca. 25 to 30 cm.) long, 2 inches (ca. 5 cm.) wide, and has a capacity of about a quart (ca. 1 liter). The =colon= is about 15 feet (ca. 4 to 5 m.) long. Its caliber is at first about the same as that of the cæcum, but diminishes to about the width of the small intestine.

FIG. 305.—LIVER OF SHEEP, VISCERAL SURFACE; HARDENED in situ. ]

The =liver= weighs about 20 to 25 ounces (ca. 550 to 700 gm.). It lies entirely to the right of the median plane. The parietal surface is related almost exclusively to the right part of the diaphragm. The visceral surface presents extensive reticular and abomasal impressions, and a small omasal impression internal to the portal fissure. The umbilical fissure is deep and partially divides the gland into two chief lobes. The caudate lobe is prismatic and blunt-pointed. The neck of the gall-bladder is long. The bile-duct joins the pancreatic duct to form a =common duct= (Ductus choledochus communis) which opens into the duodenum about one foot (ca. 30 cm.) from the pylorus.

The =pancreas= is arranged as in the ox. Its duct unites with the bile-duct.

The =spleen= (Fig. 301) is somewhat triangular, with the angles rounded off. It weighs about three or four ounces (ca. 100 grams). Its length is about five inches (ca. 12 to 13 cm.) and its greatest width about four inches (ca. 10 cm.). The parietal surface is convex and is related to the diaphragm, to which rather more than the anterior third is adherent. The visceral surface is concave and its anterior half is attached to the dorsal curvature of the rumen. The dorsal end or base is attached to the left crus of the diaphragm under the last two or three ribs. The hilus is at the posterior basal angle. The ventral end is narrower and thinner than the base; it is situated opposite the ninth and tenth ribs above their middles.

FIG. 306.—LIVER OF SHEEP, PARIETAL SURFACE; HARDENED in situ. ]

DIGESTIVE SYSTEM OF THE PIG

THE MOUTH

The =rima oris= is extensive, the angles of the mouth being situated far back. The =upper lip= is thick and short, and is blended with the snout; the =lower lip= is small and pointed. The labial glands are few and small.

The mucous membrane of the =cheeks= is smooth. The =buccal glands= are compactly arranged in two rows opposite the cheek teeth. The =parotid duct= opens opposite the fourth or fifth cheek tooth.

The =hard palate= is long and narrow; it is marked by a median furrow, on each side of which are twenty or more ridges. On its anterior part there is a triangular incisive papilla, at which the naso-palatine ducts open.

The =soft palate= is very thick. Its direction almost continues that of the hard palate, i. e., it is nearly horizontal. It extends to the middle of the oral surface of the epiglottis. It has a median prolongation termed the =uvula=. The oral surface presents a median furrow, on either side of which is an oval raised area, marked by numerous crypts; these elevations are the =tonsils=. Tonsillar tissue also occurs in the lateral walls of the fauces.

FIG. 307.—TONGUE OF PIG.

1, Apex; 2, dorsum; 3, root; a, orifices of ducts of lingual glands; b, papillæ of root; c, vallate papilla (not really so distinct as in figure); d, foliate papilla; e, fungiform papillæ; f, epiglottis (pulled back); g, median glosso-epiglottic fold. (Ellenberger-Baum, Anat. d. Haustiere.) ]

The =tongue= is long and narrow and the apex is thin. Two or three vallate papillæ are present. The fungiform papillæ are small and are most numerous laterally. The filiform papillæ are soft and very small. On the root there are soft, long, pointed papillæ, directed backward. Foliate papillæ are also present.

There is a well-marked median glosso-epiglottic fold, on either side of which is a depression (Vallecula epiglottica). The frenum linguæ is double.

The =dental formula= of the pig is:

( 3 1 4 3 ) 2 ( I - C - P - M - ) = 44 ( 3 1 4 3 )

The formula for the temporary teeth is:

( 3 1 4 ) 2 ( Di - Dc - Dp - ) = 32 ( 3 1 4 )

The =upper incisors= are small; they are separated from each other by spaces, and from the canines by a larger interval. The first incisors are the largest, are convergent, and have no distinct neck. The second are narrower and somewhat smaller. The third (corner) incisors are much smaller, are flattened laterally, and have three small eminences on the crown.

The =lower incisors= are almost horizontal and are convergent and close together. The first and second are about equal in size, prismatic, and deeply implanted in the jaw. The labial surface is slightly convex, the lingual concave and marked near its extremity by a ridge. The third incisor is much smaller and has a short narrow crown and a distinct neck.

FIG. 308.—SKULL OF PIG ABOUT A YEAR AND A HALF OLD, SCULPTURED TO SHOW THE EMBEDDED PARTS OF THE TEETH.

I1–3, Incisors; C, canines; P1–4, premolars; M1–3, molars. ]

The =canine teeth= or tusks of the male are greatly developed and project out of the mouth. The upper canine of the boar may be about three or four inches (ca. 8 to 10 cm.) long. The crown is conical and is curved somewhat backward and outward; the embedded part is curved and has a large pulp cavity. The lower canine may reach a length of eight inches or more (ca. 20 cm.); the crown is prismatic and is curved backward and outward in front of the upper one, so that the friction between the two keeps a sharp edge on the lower tooth. In the sow they are much smaller.

FIG. 309.—SUPERFICIAL GLANDS OF HEAD OF PIG.