The document provides an extensive overview of the anatomy and functions of the small intestine, detailing its length, surface area adaptations for absorption, and structural components such as plicae circulares, intestinal villi, and lymphatic follicles. It also describes the duodenum's parts, their peritoneal relations, and vascular supply, as well as differences between the jejunum and ileum. Additionally, it discusses conditions affecting the intestine, such as intestinal obstruction and hernias.

1. •ANATOMY OF THE
SMALL INTESTINE

2. {kqnzkUr
• ^^vl`t% ‘ys”e.k’pkfi ;% izlkn% ijkser% ra iP;ekua fiRrsu
ok;q’pkI;uq /kkofrAA
rrksvL;kU=kf.k tk;Urs xqna ofLr’p nsfgu%AA** ¼lq-’kk-
4@25&26½
• vkpk;Z lqJqr ds vuqlkj jDr vkSj dQ ds lkjre Hkkx esa fiRr
ds }kjk idrs le; mlesa ok;q Hkh vk tkrh gS] rc mlls vkU= dh
yEckbZ lk<s rhu O;ke ,oa fL=;ksa esa rhu O;ke crk;h gSA
• ^^ lk/kZf=O;kekU;U=kf.k iqalk] L=h.kke/kZO;keghukfu**AA
¼lq-’kk-5@8½

3. introduction
• Extend from pylorus to
ileocaecal junction.
• 6m long.
• Length is greater in male than in
female, greater in cadaver due to
loss of tone in the living.
• For absorption of digested food a
very large surface area is
required. This is achieved by
• A) the great length of intestine.
• B) the presence of circular fold
of mucous membrane, villi and
microvilli.

6. Plicae circulares
• The circular fold of mucous membrane,
plicae circulars or valve of kerkring
from complete or incomplete circle.
• They almost absent in distal half of
ileum.
• Apart from increasing the surface area
for absorption, by slowing down the
passage of intestinal contents.
• They begins in second part of
duodenum, become large and closely
set below the level of major duodenal
papilla.
• Continue proximal part of jejunum then
diminished progressively in size and
number.

7. Intestinal villi
• Finger like projections of mucous
membrane, visible to the naked eye.
• They give the surface of intestinal
mucosa a velvety appearance.
• Large and numerous in duodenum and
jejunum , but smaller and fewer in
ileum.
• They increase the surface area of
intestine about eight times.
• They vary in density from 10 to 40 per
square mm, 1 to 2 mm long.
• Villus is covered by a layer of absorptive
columnar cells, the surface of these cells
has a striated border, called microvilli.

8. Intestinal gland or crypts of
lieberkuhn
• Simple tubular glands,
distributed over the entire
mucosal membrane of jejunum
and ileum.
• Open by small circular aperture
on the surface of mucous
membrane between villi.
• They secrete digestive enzymes
and mucus.
• Duodenal glands or burners‘
gland lie in sub mucosa .
• Small, compound tubuloacinar
glands which secrete mucus.

9. Lymphatic follicles
• Contains two types of lymphatic follicles.
• Solitory lymphatic follicles - 1
or 2mm in diameter.
• Distributed throughout small & large
intestine. Aggregated lymphatic
follicles or peyer’s patches
form circular or oval patches,
• Length = 2 to 10cm & containing 10 to
over 200 follicles.
• Largest & most numerous in ileum, &
small, circular & fewer in distal jejunum.
• Placed lengthwise along the antimesenteric
border of intestine.
• Payer’s patches - most numerous at
puberty, diminished in size & number, may
persist up to old age, get ulcerated in
typhoid fever, oval ulcers.

10. xzg.kh
• ^^vXU;f/k”BkueUuL; xzg.kkn~ xzg.kh erkA
ukHks:ifj lkâfXu cyksiLrEHk c`afgrk**AA ¼p-fp-15@56½
• vkpk;Z pjd ds vuqlkj xzg.kh dks vfXu dk vkJ; gksus ,oa vUu dks xzg.k djus
ds dkj.k bls xzg.kh laKk nsrs gq, bldh fLFkfr ukfHk ds mij crk;h gSA
• ^^ iDokek’k;e/;LFkk xzg.kh lk izdhfrZrk**A ¼lq-m-40@169½
• lqJqr us Hkh vkek’k; ,oa iDok’k; ds e/; fLFkr vo;o dks xzg.kh laKk nh gSA
• ^^“k”Bh fiRr/kjk uke] ;k prqZfo/keUuikueqiHkqDrekEk’k;kr~ izP;qr
iDok’k;ksifLFkra /kkj;fr**AA ¼lq-’kk-4@17½
• vkpk;Z lqJqr us fiRr/kjk dyk dk LFkku Hkh vkek’k; ,oa iDok’k; ds e/; crk;k
gSA lsou fd;s prqfoZ/k vUuiku tks vkek’k; ls vkrk gS] mls xzg.k djus okyk
vo;o xzg.kh gSA xzg.kh esa fiRr ds }kjk vUu th.kZ gksdj iDok’k; dh vksj
ikpu ds fy, Hkst fn;k gSA

11. DUODENUM
SHAPE: C-shaped loop
LENGTH: 10 inches
BEGINNING: at pyloro-
duodenal junction
TERMINATION: at
duodeno-jejunal flexure
PERITONEAL
COVERING:
retroperitoneal

15. parts
• The duodenum is
divided into (4) parts:
• 1st
: Superior.
• 2nd
: Descending
(vertical).
• 3rd
: Inferior
(Horizontal)
• 4th
: Ascending

17. Length – surface anatomy
part length level
FIRST PART
(Superior)
2 inches
(5cm)
L1
(transpyloric
plane)
Second part
(descending)
3 inches
(7.5)
Descends from
L1 to L3)
Third part
(Horizontal)
4 inches (10
cm)
L3 subcoastal
plane
Fourth part
(Ascending
Part
1 inches
(2.5 cm)
Ascends from
L3 to L2

19. Structures Related
psoas
pancreas

23. Second part of duodenum
• About 7.5cm long.
• Begins at superior duodenal
flexure, passes downwards to
reach left at inferior duodenal
flexure.
• Reach L1 vertebrae, to become
continuous with third part.
• Peritoneal relations =
• Retroperitoneal & fixed.
• Anterior surface covered with
peritoneum, except near middle,
where it is directly related to the
colon

24. OPENINGS IN
SECOND PART OF DUODENUM
1. Common opening of
bile duct & main
pancreatic duct: on
summit of major
duodenal papilla.
2. Opening of accessory
pancreatic duct (one
inch higher): on
summit of minor
duodenal papilla

25. Duodenal papilla
• Major duodenal papilla
- present posteromedially.
• 8 to 10cm distal to pylorus.
• The hepatopancreatic ampulla
opens at the summit of papilla.
• Minor duodenal papilla -
6 to 8cm distal to pylorus.
• Presents opening of accessory
pancreatic duct.
• Plica longitudinalis -
below major duodenal papilla, a
longitudinal fold.

26. RELATIONS OF SECOND PART
X
Anterior
Right lobe of Liver
Transverse Colon
Small intestine
Posterior
1) Right kidney
2) Right edge
of inferior vena
cava
Lateral
R Colic
Flexure
Medial
1) Pancreas
2) Bile duct

28. Third part of duodenum
• About 10cm long.
• Begins at inferior duodenal
flexure.
• On the right side of lower
border of third lumbar
vertebrae.
• Passes almost horizontally &
slightly upwards in front of
inferior vena cava.
• Ends by joining the fourth part
front of abdominal aorta.

29. Peritoneal relations
• Retroperitoneal & fixed.
• Anterior surface covered
with peritoneum.
• Except in the median plane.
• Crossed by superior
mesenteric vessels & by the
root of mesentery.

30. RELATIONS OF THIRD PART
 Anterior:
a)root of mesentery
b) Superior mesenteric vessels
 Posterior:
1) Right psoas major
2) Inferior vena cava
3) Abdominal aorta
4) Inferior mesenteric vessels.
• Superior - head of pancrease
with uncinate process.
• Inferiorly - coils of jejunum
1 2 3

34. Suspensory muscle of duodenum or
ligament of treitz
• Fibromuscular band which suspends &
supports duodenojejunal flexure.
• Arise from right crus of diaphragm, close to
right side of oesophagus.
• Passes downwards behind pancreas, attached
to posterior surface of duodenojejunal
flexure & third & fourth parts of duodenum.
• Made up of –
• Upper part - striped muscle fiber.
• Middle part – elastic fibers.
• Lower part - plain muscle fibers.
• Its contraction - increase angle of
duodenojejunal flexure.
• Abnormality - its attached only to
flexure, then its contraction may narrow the
angle of flexure, causing partial obstruction
of gut.

35. Blood Supply & Lymph drainage
 Because the duodenum is
derived from both: Foregut &
Midgut,
 It has its Arterial Supply from :
 Celiac & Superior mesenteric
arteries.
 Venous Drainage to :
 Superior mesenteric& Portal
veins.
 LYMPHATIC DRAINAGE:
Celiac & Superior mesenteric
lymph nodes.

43. JEJUNUM & ILEUM
 SHAPE: Coiled tube
 LENGTH: 5.75 meters (20 feet)
0r aprox 6m
 BEGINNING: at Duodeno-
jejunal flexure
 TERMINATION: at Ilieo-caecal
junction
 EMBRYOLOGICAL ORIGIN:
Midgut
 Blood SUPPLY: Superior
mesenteric A & V
 LYMPHATIC DRAINAGE:
Superior mesenteric lymph
nodes

46. JEJUNUM ILEUM
LENGTH Shorter (proximal 2/5) of SI Longer (distal 3/5) of SI
DIAMETER Wider Narrower
WALL Thicker (more plicae
circulares)
Thinner (less plicae circulares)
APPEARANCE Dark red (more vascular) Light red (less vascular)
VESSELS High & Less arcades (long
terminal branches)
Low & More arcades (short
terminal branches
MESENTERIC FAT Small amount & away from
intestinal border
Large amount & close to
intestinal border
LYMPHOID TISSUE Few aggregations Numerous aggregations
(Peyer’s patches)

47. features jejunum ileum
Lumen Wider & often empty Narrower & often loaded
Mesentery 1. Window present
2. Vasa recta longer &
fewer
1. No window
2. Vasa recta shorter &
more numerous.
Circular mucosal
folds
Larger & more closely set Smaller & sparse
Villi Large, thick (leaf like) &
more abundant
Shorter , thinner & less
abundant.
Peyer’s patches absent Present
Solitary lymphatic
follicles
fewer More numerous

48. Meckel’s diverticulum
• Persistent proximal part of the
vitellointestinal duct which is present
in the embryo, & which normally
disappears during 6th
week of
intrauterine life.
• It occurs in 2% subjects.
• Usually it is 2 inches or 5cm long.
• It is situated about 2 feet or 60cm
proximal to ileocaecal valve, attached
to antimesenteric border of ileum.
• Calibre is equal to that of ileum.
• Apex may be free or may be attached
to the umbilicus, to the mesentery, or
to any other abdominal structure by a
fibrous band.
• 2 times more common in men

50. Intestinal obstruction
• A gastrointestinal condition
in which digestive material
is prevented from passing
normally through bowel.
• It can be caused by fibrous
tissue that compress the gut.
• Stricture - narrowing of
section of intestine that
causes problems by slowing
or blocking the movement
of food through the area.

51. Volvulus or twisting of intestine
• When a loop of intestine
twists around itself &
mesentery that supports it,
resulting in a bowel
obstruction.
• In children's most affected
small intestine.

52. Intussusception
• Is a form of bowel obstruction
in which one segment of
intestine telescopes inside of
another.
• Usually occurs at the junction
of small intestine & large
intestine

53. Intestinal perforation.
• Known as ruptured bowel,
defined as a loss of continuity of
the bowel wall
• Is a hole in wall of intestine due
to different diseases or trauma.
• Symptoms –
• Abdominal pain or cramping,
which is usually severe.
• Bloating or swollen abdomen.
• Fever or chills.
• Nausea and vomiting.
• Pain or tenderness when you
touch abdomen.

54. Intestinal hernia.
• A hernia occurs when an organ
pushes through an opening in
the muscle or tissue that holds it
in place.
• The intestine may break through
a weakened area in the
abdominal wall

55. THANK YOU