The liver lies almost entirely to the right of the median plane. Its
long axis is directed obliquely downward and forward, about parallel
with the median plane, and corresponds to the curvature of the right
portion of the diaphragm. It is less extensive, but thicker than that of
the horse. Its average weight is about 10 to 12 pounds (ca. 4.5 to 5.5
kg.).
In small subjects the weight (according to Schmaltz) varies from 6½ to
10 pounds (ca. 3 to 4.5 kg.), in large subjects from 11 to 13 pounds
(ca. 5 to 6 kg.). According to Schneider, the average weight is about
13 pounds (ca. 6 kg.)—a little over 1 per cent. of the live weight and
about 2 per cent. of the dressed carcass.
When hardened _in situ_, its configuration adapts it accurately to the
structures with which it is in contact.
The =parietal surface= is convex and is for the most part applied to the
right part of the diaphragm, but a small part of it is in direct contact
with the last two ribs and with the flank at the lumbo-costal angle. It
faces upward, forward, and to the right.
The curvature of the parietal surface is not regular. It is marked,
except in its ventral part, by a blunt oblique ridge which corresponds
to the basal border of the right lung. This prominence divides the
surface into two areas. Of these, the external one is directed
outward, is only slightly convex, and often shows impressions of the
last three ribs. The inner area presents a depression produced by the
right crus of the diaphragm, and otherwise is regularly convex and
adapted to the tendinous center and sternal portion of the diaphragm.
The falciform ligament is attached to the surface from the œsophageal
notch to the umbilical fissure.
[Illustration:
FIG. 297.—LIVER OF YOUNG OX, VISCERAL SURFACE; HARDENED _in situ_.
]
The =visceral surface= is concave and very irregular; it presents
impressions of the chief organs which are in contact with it—the omasum
and reticulum. It is also related to the pancreas and duodenum.
The following markings are quite distinct on the visceral surface of
well hardened specimens: (1) The omasal impression (Impressio omasica)
is a deep central cavity below the portal fissure. (2) The reticular
impression (Impressio reticularis) is a smaller marginal depression
below the œsophageal notch and the inner part of the preceding, from
which it is separated by a rounded ridge. (3) The abomasal impression
(Impressio abomasica), present only in the calf, is produced by the
anterior part of the abomasum. It lies along the ventral part of the
surface, and is separated by ridges from the preceding impressions. It
disappears as the omasum and reticulum increase in size and displace
the abomasum from contact with the liver. (4) Shallow grooves for the
=S=-shaped portion of the duodenum (Impressio duodenalis) may be found
above and external to the portal fissure. (5) The fossa of the
gall-bladder (Fossa vesicæ felleæ) is distinct when that organ is
full. In the calf the omasal impression is small, and the abomasal one
large in correspondence with the relative sizes of these two sacs.
The =portal fissure= is a well defined rounded depression, situated
dorsal to the omasal impression. It contains, besides the vessels and
duct, several large hepatic lymph glands. Above and external to it a
part of the pancreas is attached.
[Illustration:
FIG. 298.—LINE DRAWING OF LIVER OF OX, VISCERAL SURFACE OF SOFT
SPECIMEN.
_L.g._, Hepatic lymph glands at portal fissure.
]
The =dorsal border= is short and thick; it extends backward a short
distance beyond the upper part of the last rib. It presents the large,
thick, quadrilateral =caudate lobe=, and a deep depression for the right
kidney and adrenal.
The =ventral border= is short and thin and has no interlobar incisures.
The =right= (or external) =border= is marked by a small umbilical
fissure, in which the ligamentum teres is attached in the young subject.
The =left border= presents the œsophageal notch below its middle. Above
this it is practically median in position, and lodges the posterior vena
cava, which is partially embedded in the gland. Below the notch the
border extends an inch or two (ca. 2.5 to 5 cm.) to the left of the
median plane opposite the ventral third of the sixth rib.
There is no left lateral ligament. The falciform ligament is usually
present, but the ligamentum teres is found only in young subjects. The
lesser omentum leaves the liver along a line extending from the
œsophageal notch to the portal fissure. The only distinct lobe in the
adult is the caudate (Processus caudatus).
[Illustration:
FIG. 299.—PANCREAS OF OX, GASTRO-INTESTINAL SURFACE, WITH RELATED
ORGANS.
The position of some of the larger lymph glands (_l.g._) is indicated
by dotted line; also the intraglandular course of the pancreatic
duct. Probe is passed through epiploic foramen (of Winslow).
]
A =gall-bladder= (Vesica fellea) is present. This is a pear-shaped sac,
four to six inches (ca. 10 to 15 cm.) long, which lies partly on the
visceral surface of the liver (to which it is attached), but largely on
the abdominal wall at the lower part of the eleventh or twelfth
intercostal space. It may be regarded as a diverticulum of the
bile-duct, enlarged to form a reservoir for the bile. Its neck is
continued by the =cystic duct= (Ductus cysticus), which joins the
hepatic duct at an acute angle just outside of the portal fissure, to
form with it the bile-duct (Ductus choledochus). The latter is short and
enters the second bend of the =S=-shaped curve of the duodenum, _i. e._,
about two feet (ca. 60 cm.) from the pylorus. Several small ducts
(Ductus hepato-cystici) open directly into the gall-bladder.
In the new-born calf the liver is relatively much larger than in the
adult. The visceral surface presents, below the portal fissure, a
large rounded eminence, which is caused by the presence in the
underlying gland substance of a large venous sinus into which the
umbilical and portal veins empty. A large vessel, the =ductus
venosus=, leads from this sinus directly to the posterior vena cava.
Just external to this elevation is a small but distinct lobe about two
inches long (Processus papillaris?). The umbilical fissure is deep and
partially divides the gland into two chief lobes.