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LO74 THE DIGESTIVE SYSTEM. 
The head is placed opposite the second and upper part of the third luubar vertebra, whilst 
the body runs to the left, about the level of the first lumbar vertebra. 1t should he added, that 
very often the lower portion of the head projects some distance below the subcostal plane, and 
thus lies in the umbilical region. 
In shape the pancreas, when hardened an situ, is very irregular (Hig. 723), 
its right end being flattened and hook-like, whilst the rest. of the organ 18 pris- 
matic and three-sided. It may, perhaps, in general form be best compared to 
the letter y placed thus c, particularly if the stem and hook of the letter be 
thickened. 
The gland is divisible into a head, a neck, and a body. The head corresponds 
to the hook of the oe, and runs downwards and to the left alone the second 
and third portions of the duodenum. The stem of the represents the body 
of the gland, and the narrow part connecting the two 1s the neck. 
When removed from the body without previous hardening, the pancreas loses 
its true form, and becomes drawn out into a slender, elongated, tongue-shaped 
mass, with a wider end turned towards the duodenum, and a narrow ‘end corre- 
sponding to the tail. 
Its total length, when fixed zn situ, is about 5 or 6 inches (12°5 to 15 em.) ; after removal, if 
not previously hardened, it is easily extended to a length of 8 inches (20 em.). 
Its weight is usually about 3 ounces (87 grammes). 
Relations.—The general position and relations of the pancreas may be brietly 
expressed as follows :—The head (Fig. 725) lies in the concavity of the duodenum, 
with the vena cava and aorta behind it; the body crosses the left kidney and 
suprarenal capsule; and the tail touches the lower part of the spleen. The 
creater part of the organ lies behind the stomach, which must he detached 
from the great omentum, and turned upwards, in order to expose it. 
In describing the detailed relations, each part of the organ will require to 
be considered separately. 
The head (caput pancreatis) is the large flattened and somewhat dise-shaped portion 
of the gland which lies in the concavity of the duodenum, extending along its second 
and third portions almost as far as the duodeno-jejunal flexure. Above, in its right half, 
it is continuous with the neck ; whilst to the left of this it is separated from the neck by 
a deep notch (incisura pancreatis), in which lie the superior mesenteric vessels (Fig. 723). 
Its right and lower borders are moulded on to the side of the duodenum, which lies in a 
eroove of the gland substance—the common bile duct being interposed as far down 
as the middle of the second portion of the duodenum. The posterior surface of the 
head is applied to the front of the inferior vena cava; it also lies on the renal vessels, 
and, at its left end, on the aorta as well. Its anterior surface is in contact above and 
on the right with the beginning of the transverse colon (Fig. 724), without the inter- 
position of the peritoneum as a rule. Below this it is clothed by peritoneum, and is 
covered by the small intestine. 
The superior mesenteric vessels, after passing forward through the pancreatic notch, 
descend in front of that portion of the head (processus uncinatus) which runs to the left 
along the third part of the duodenum. The superior pancreatico- duodenal vessels run 
downwards, and break a on the front of the head (Fig. 723). 
The neck (Fig. 72 23) is a comparativ ely attenuated portion of the gland which lies 
in front of the portal vein, and connects the head to the body. Springing from the upper 
and right portion of the Reni it runs upwards and to the left for about 1 inch (25 mm.), 
and then passes into the body. 
The neck is about # inch (18 mm.) in width, and less than $ inch (12°56 mm.) in thickness. In 
front and to its right he the first part of the duodenum and the pylorus ; behind and to the left it 
rests upon the beginning of the portal vein, which is formed under cover of its lower border, by the 
union of the splenic and superior mesenteric veins. It has a partial covering of peritoneum on its — 
anterior surface ; and its beginning is generally marked off from the head by the gastro-duodenal 
artery, with its continuation the superior pancreatico- -duodenal, which lies in a groove of the 
gland substance between the head and neck. 
The neck, which was first described by Symington, forms as distinct and definite a division 
as any other portion of the gland. 
The body is of a prismatic form, largest where it lies in front of the left kidney, 
and usually somewhat tapering towards the tail (Fig. 724). Beginning at the termina- 
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