Dr. Ifeanacho ABIREHabireh.com/.../08/Gross-anatomy-of-small-intestine.pdf · Gross anatomy of...

Gross anatomy of small intestine

Dr. Ifeanacho

ABIREH MBBS, MSc, PGDE, MWACS

7/31/2019 Ifeanacho Abireh www.abireh.com

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Regions of the abdomen -Nine


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Regions of the abdomen -Four


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SMALL INTESTINE This consists of the following: Duodenum Jejunum Ileum


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Duodenum C-shaped tube It is 25cm in length Has 4 parts: Superior (1st part) -5cm Descending (2nd part) -7.5cm Horizontal (3rd part) -10cm Ascending (4th part) -2.5cm 7/31/2019

Ifeanacho Abireh www.abireh.com

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Duodenum The C- curve occurs around the head of the

pancreas at L2 1st part at L1; 2nd part at L2; 3rd part at L3; 4th

part at L2 The first 2.5cm (duodenal cap) is contained

within the peritoneum of the greater and lesser omenta

The other parts are retroperitoneal


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Duodenum Majority of the duodenum lie in front of, and

to the right of the inferior vena cava and aorta


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Duodenum -1st part Runs from the pylorus to the right, then

superiorly and backwards Superior relations Inferior surface of right lobe of liver Opening of lesser sac


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Duodenum -1st part Posterior relations Gastroduodenal artery Bile duct Portal vein Inferior vena cava and medial border of right

kidney


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Duodenum -1st part • Anterior relations –gallbladder


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Duodenum -second part Curves downwards over the hilum of the

right kidney Anterior relations Covered in front with peritoneum Crossed by the attachment of the transverse

mesocolon Liver Coils of jejunum 7/31/2019


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Duodenum -second part Lateral relations Medial border of right kidney Medial relations Head of pancreas Common opening of the bile duct and main

pancreatic duct at the hepatopancreatic ampulla (of Vater)

This occurs at middle of 2nd part (10 cm from the pylorus)


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Duodenum -second part


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Duodenum -Third part Runs from the right to the left to reach the left psoas

muscle Posterior relations Right psoas muscle Gonadal vessels Ureter Inferior vena cava Aorta Inferior Inferior mesenteric artery Superior Lower border of the pancreas


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Duodenum -Third part Anterior relations Peritoneum of the posterior abdominal wall Superior mesenteric vessels Commencement of the mesentery of the small

intestine Coils of jejunum


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Duodenum -Fourth part Ascends to the left of the aorta Posterior relations Left psoas muscle Left lumbar sympathetic trunk Anterior relations Peritoneum Coils of jejunum Ends at the duodenojejunal flexure


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Duodenum The mucous membrane

of the duodenum is thrown into circular folds (except the duodenal cap)

These folds are known as plicae circulares or valvulae conniventes


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Duodenum –blood supply Superior and inferior pancreaticoduodenal

arteries First 2 cm is supplied by: Hepatic, gastroduodenal, supraduodenal,

right gastric and right gastroepiploic arteries


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Duodenum –blood supply

Venous drainage Tributaries of the superior mesenteric and

portal veins Lymph drainage Accompany the superior and inferior

pancreaticoduodenal vessels to reach Coeliac nodes Superior mesenteric nodes

7/31/2019


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Duodenum –blood supply


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Jejunum and Ileum These form the rest of the small intestine after

the duodenum Starts at the region of the ligament of Treitz Lie in the free margin of the mesentery Total length 4 to 6m


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Jejunum and ileum Jejunum is wider-bored

and thicker The wall of the jejunum

feels double The jejunum lies coiled

in the upper part of the infracolic compartment

The jejunum constitutes about 2/5

Narrow and thin-walled

The thin wall of the ileum feels single

The ileum in the lower part of the infracolic compartment and in the pelvis

Ileum 3/5


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Jejunum and Ileum

Ileal (Meckel's) diverticulum This represents the intestinal end of the

vitellointestinal duct It is a blind ended tube May contain gastric mucosa, liver or

pancreatic tissues The tip may be adherent to the umblicus; may

ulcerate or perforate


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Jejunum and Ileum

Ileal diverticulum is seen in: 2% of individuals 2ft (60 cm) from the caecum 2 in (5 cm) long


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Jejunum and ileal Blood supply Jejunal and ileal branches from left side of

superior mesenteric artery The branches form arterial arcades


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Jejunum and ileal Blood supply

These arcades are single for the upper jejunum and double for lower jejunum

Straight arteries arise from the arcades to the jejunum

These straight vessels are long and close together


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The ileal arteries are similar to the jejunal arteries

Difference Larger series of arcades

(3-5) The arcades are close to

the ileum Straight arteries are

shorter


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The end of superior mesenteric artery supplies the ileal diverticulum

It anastomoses with the arcades and with the ileocolic branch to supply terminal ileum

The veins correspond to the arteries


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Jejunum and ileum Lymph drainage Superior mesenteric nodes Nerve supply The parasympathetic -Vagal supply The sympathetic supply from T9 and 10


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Acknowledgement Last’s anatomy Gray’s anatomy Grants atlas of anatomy


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Dr. Ifeanacho ABIREHabireh.com/.../08/Gross-anatomy-of-small-intestine.pdf · Gross anatomy of...

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