The document discusses the radiological anatomy of the duodenum. It describes that the duodenal bulb is intraperitoneal while the rest of the duodenum is retroperitoneal. It notes the four parts of the duodenum and mentions folds encircle the duodenal lumen except at the papilla of Vater. The document also describes the velvety or villous pattern seen on radiographs due to trapped barium between duodenal villi.

1. The duodenal
bulb is
intraperitoneal;
the remainder of
the duodenum
envelops the
head of pancreas
and is
retroperitoneal.
RADIOLOGICAL ANATOMY OF
DUODENUM

2. RADIOLOGICAL ANATOMY OF
DUODENUM
1.Duodenal cap
2.2nd part of
duodenum.
3.3rd part of
duodenum
4.Superior
mesenteric
artery
impression.
5.4th part of
duodenum

3. RADIOLOGICAL ANATOMY OF
DUODENUM
The folds in the
second, third, and
fourth portions of
the duodenum
encircle the lumen
of the duodenum
except at the
papilla of Vater.

4. RADIOLOGICAL ANATOMY OF
DUODENUM
The mucosa of the
duodenum varies from a
smooth to a
velvety pattern. Barium
trapped between duodenal
villi results in a “velvety”
pattern of dots and lines.
This also is known as a
villous pattern. The villi
are just at the limits of
resolution because they are
about 1 mm in cross
section.

5. RADIOLOGICAL ANATOMY OF
DUODENUM
The papilla of
Vater is found on
the mid to distal
medial wall of the
second part of the
duodenum, seen
as a 5–8 mm
elevation (filling
defect in the
barium pool
or hemispheric
line).

6. RADIOLOGICAL ANATOMY OF
DUODENUM
The transition
between the
duodenum and
jejunum is
better described
as the
“duodenal-
jejunal junction,”
rather than the
“ligament of
Treitz.”

7. RADIOLOGICAL ANATOMY OF
DUODENUM
On AP projection,
D1 is located to
the right of spine
and duodeno-
jejunal flexure to
the left of the left
pedicle at the
same level or
higher.