1226 SURFACE AND SURGICAL ANATOMY. 
just large enough to easily admit the finger. In resecting the pylorus, the 
surgeon should remember that the gastro-duodenal vessels he behind the first part 
of the duodenum, about 1 in. to the right of the pylorus. 
The second part of the duodenum descends in the right vertical Poupart plane, and 
is crossed about its middle, at the level of the infracostal plane, by the attachment of 
the transverse mesocolon. It lies in front of the hilus and lower part of the inner 
border of the right kidney. 
The transverse portion of the third part of the duodenum occupies the upper 
part of the umbilical region, and crosses the middle lme about 1 in. above a line 
joining the highest part of the ilac crests; behind its commencement is the upper 
part of the right ureter. 
The ascending portion of the third part of the duodenum crosses the infra- 
costal plane, and ascends upon the left side of the vertebral column opposite the 
second and third lunbar vertebre. 
The duodeno-jejunal flexure, which lies in the transpyloric plane 1 in. to the 
left of the mesial plane, is the landmark which the surgeon makes for when he 
wishes to identify the commencement of the jejunum (Fig. 677, p. 1004). To find 
the flexure the omentum and transverse colon should be thrown upwards and the 
finger passed along the lower layer of the transverse mesocolon to the left side of 
the vertebral column. The flexure les in the angle or recess formed by the left side 
of the second lumbar vertebra and the under surface of the body of the pancreas. 
With the finger in this recess the commencement of the jejunum may be hooked 
forward a little to the left of the superior mesenteric vessels at the root of the 
mesentery. In connexion with the duodeno-jejunal junction is the duodeno-jejunal 
fossa (inferior duodenal fossa of Jonnesco), formed by a fold of peritoneum which 
stretches from the left side of the fourth or ascending part of the duodenum 
upwards to become attached to the peritoneum of the posterior abdominal wall close 
to the inner border of the left kidney. The free edge of the fold and the mouth of 
the fossa look upwards. This is one of the situations at which an internal hernia 
sometimes develops, the sac, as it enlarges, extending further and further into the 
extra-peritoneal tissue on the posterior abdominal wall. Should strangulation 
occur, the lower edge of the orifice must be divided in a downward direction, in 
order to avoid the superior mesenteric vein which curves round the anterior and 
upper aspects of the orifice (Treves). 
Small Intestine.—The coils of the small intestine dip downwards into the 
pelvis, overlap the ascending and descending portions of the colon, and extend 
upwards to the attachment of the transverse mesocolon. To the left of the 
mesentery they reach as far as the under surface of the pancreas and the splenic 
flexure of the colon: here they are overlapped by the lower part of the stomach, 
from which they are separated by the transverse mesocolon. The only certam 
means which the surgeon has of distinguishing the upper from the lower coils of 
small intestine is by their relation to the duodeno-jejunal flexure and the ileo- 
cecal junction. Occasionally the Peyer’s patches can be seen from the peritoneal 
aspect and the ileum thereby identified. The terminal portion of the vlewm, which 
is attached by the lower end of the mesentery to the upper part of the right lateral 
wall of the true pelvis, crosses over its brim, and ascends along the inner edge of 
the ceeum before opening into it. The terminal loop of the ileum may be hooked 
up by passing the finger along the inner side of the caecum downwards over the 
inner border of the psoas and the external iliac vessels into the pelvis. 
Large Intestine—The cecum, which occupies the right iliac region, comes 
into contact with the anterior abdominal wall immediately above the outer third of 
Poupart’s ligament; laterally, it extends from the anterior superior iliac spine to 
the brim of the pelvis. When dilated, it extends considerably beyond these limits ; 
when empty, it is generally more or less completely overlapped by small intestine. 
The ileo-cecal valve lies obliquely a little below the intertubercular plane, imme- 
diately internal to where that plane is intersected by the Poupart plane; it 1s 
situated, therefore, at the upper and outer angle of the right hypogastric region, 
opposite a point on the surface 1 in. below the mid-point of a line joming the 
umbilicus and the anterior superior ilac spine. 
