The jejunum, ileum & mesentery

1. The Jejunum, Ileum & Mesentry

2. SMALL INTESTINE
The small intestine extends from:
 The pylorus to the ileocaecal junction
 It is about 6 meters long
The length is greater in males than in females
It is divided into:
1. An upper, fixed part, called the duodenum,
25 cm in length
2. A lower, mobile part, forming many convoluted tube.
The upper two-fifths of the mobile intestine are known
as the jejunum, and the lower three-fifths are known
as the ileum.

4. RELEVANT FEATURES
Large Surface Area
a. The great length of the intestine.
b. The presence of circular folds of mucous membrane, villi and
microvilli.
 The circular folds of mucous membrane:-
Plicae circularis or valve of Kerkring form complete or incomplete
circles
o begin in the 2nd part of the duodenum
o continue to proximal half of the jejunum
o diminish progressively in size and number in:-
 distal half of the jejunum and
 the proximal half of the ileum.
o They are almost absent in the distal half of the ileum

6. Intestinal Glands or crypts of Lieberkuhn
• These are simple tubular glands distributed over the
entire mucous membrane of the jejunum and ileum
• The duodenal glands or Brunner’s glands lie in the
submucosa.
Lymphatic Follicles
• Solitary lymphatic follicles
• Aggregated lymphatic follicles or Peyer’s patches.

7. JEJUNUM AND ILEUM
The jejunum and ileum:-
• Suspended from the posterior abdominal wall by
the mesentery and
•The jejunum and ileum are the greatly coiled parts
of the small intestine
• Have considerable mobility
• The jejunum: upper 2/5th of the small intestine
• Jejunum lies between duodenum and the ileum
• The ileum: lower 3/5th of the small intestine
• The jejunum begins at the duodenojejunal flexure
• The ileum terminates at the ileocaecal junction.

8. Suspensory muscle of the duodenum

14. Arterial Supply
The arterial supply to jejunum and ileum is derived
from the jejunal and ileal branches of the
superior mesenteric artery & drained by
corresponding veins
• These branches anastomose to form loops,
called arcades. From the arcades, long and
straight arteries arise, called vasa recta

16. Lymphatics
• Lymph from lacteals (lymphatic capillary) drains
into plexuses in the wall of gut. From here it
passes into lymphatic vessels in the mesentry
• It ultimately drains in nodes present in front of
the aorta at the origin of superior mesentric
artery.

17. Nerve Supply
• The sympathetic nerves are from T9 - T11
segments
• Parasympathetic is from Vagus

18. MECKEL’S DIVERTICULUM (Diverticulum Ilei)
• A remnant of the vitello-intestinal
duct which normally disappears
during 6th week of intra uterine life
• congenital anomaly
• the diverticulum usually appears as a
finger-like pouch
• It may cause intestinal obstruction

19. MECKEL’S DIVERTICULUM
1. It occurs in 2% subjects
2. Usually it is 5 cm long
3. It is situated about 60 cm proximal to the
ileocaecal valve, attached to antimesenteric
border of the ileum.
4. Its calibre is equal to that of the ileum
5. Its apex may be free or may be attached to
the umbilicus or to any other abdominal
structure by a fibrous band

21. Mesentry
• Fold of peritoneum
• Broad, fan shaped that suspends the coils of jejunum
& ileum from the posterior abdominal wall
Border
• The attached border or root of mesentry is 15 cm long
• Its directed obliquely downwards & to the right
• Extends from the duodenojejunal flexure (left) to the
upper part of right sacroiliac joint

22. Between these two points (duodenojejunal flexure (left)
to the upper part of right sacroiliac joint) the root of the
mesentery crosses:
,1)The horizontal (3rd ) part
of the duodenum
2)Abdominal Aorta
3)Inferior vena cava
4)Right ureter
5)Right Psoas major
• The breadth of mesentry
is maximum in the
central part & gradually
diminishes towards both
ends

23. Contents of the mesentery
1. Jejunal & ileal branches of the superior mesentric
artery
2. Accompanying vein
3. Autonomic nerve plexuses
4. Lymphatics or lacteals
5. 100-200 lymph nodes
6. Connective tissue with fat