Duodenum Flashcards
Characteristics of the duodenum
Shortest, widest and most fixed part of the small intestine
Location of the duodenum
Above the level of umbilicus
Opposite first, second and third lumbar vertebrae
What are the four parts of the duodenum?
First or superior part is 5 cm or 2 inches long
Second or descending part is 7.5 cm or 3 inches long
Third or horizontal part is 10 cm or 4 inches long
Fourth or ascending part is 2.5 cm or 1 inch long
Which parts of the duodenum are covered with peritoneum?
The duodenum is mostly retroperitoneal and fixed
However, at its two ends it is suspended by folds of peritoneum, and is, therefore, mobile
Anteriorly, the duodenum is only partly covered with peritoneum
Course of the first part of the duodenum?
Begins at the pylorus, and passes backwards, upwards and to the right to meet the second part at the superior duodenal flexure
What are the peritoneal relations of the first part of the duodenum?
The proximal 2.5 cm is movable. It is attached to the lesser omentum above, and to the greater omentum below.
The distal 2.5 cm is fixed. It is retroperitoneal. It is covered with peritoneum only on its anterior aspect.
First part of duodenum: Visceral anterior relations
Quadrate lobe of liver, and gallbladder
First part of duodenum: Visceral posterior relations
Gastroduodenal artery, bile duct and portal vein
First part of duodenum: Visceral superior relations
Epiploic foramen
First part of duodenum: Visceral inferior relations
Head and neck of the pancreas
Course of the second part of the duodenum?
7.5 cm long
Begins at the superior duodenal flexure, passes downwards to reach the lower border of the third lumbar vertebra, where it curves towards the left at the inferior duodenal flexure, to become continuous with the third part
What are the peritoneal relations of the second part of the duodenum?
It is retroperitoneal and fixed
Its anterior surface is covered with peritoneum, except near the middle, where it is directly related to the colon
Second part of duodenum: Visceral anterior relations
Right lobe of the liver
Transverse colon
Root of the transverse mesocolon
Small intestine
Second part of duodenum: Visceral posterior relations
Anterior surface of the right kidney near the medial border
Right renal vessels
Right edge of the inferior vena cava
Right psoas major
Second part of duodenum: Visceral medial relations
Head of the pancreas
The bile duct
Second part of duodenum: Visceral lateral relations
Right colic flexure
What special features are seen in the second part of the duodenum?
Major duodenal papilla
Minor duodenal papilla
Plica longitudinalis
What is the major duodenal papilla?
Elevation present posteromedially, 8 to 10 cm distal to the pylorus
What opens into the summit of the major duodenal papilla?
Hepatopancreatic ampulla
Where is the minor duodenal papilla?
Present 6 to 8 cm distal to the pylorus
What opens into the minor duodenal papilla?
Opening of the accessory pancreatic duct.
What is the plica longitudinalis?
A longitudinal fold seen below the major duodenal papilla
Course of the third part of the duodenum
10 cm long
It passes almost horizontally and slightly upwards in front of the inferior vena cava, and ends by joining the fourth part in front of the abdominal aorta
Peritoneal relations of third part of duodenum
Retroperitoneal and fixed
Its anterior surface is covered with peritoneum, except in the median plane, where it is crossed by the superior mesenteric vessels and by the root of the mesentery
Third part of the duodenum: Visceral anterior relations
Superior mesenteric vessels
Root of mesentery
Third part of the duodenum: Visceral posterior relations
Right ureter
Right psoas major
Right testicular or ovarian vessels
Inferior vena cava
Abdominal aorta with origin of inferior mesenteric artery
Third part of the duodenum: Visceral superior relations
Head of the pancreas with uncinate process
Third part of the duodenum: Visceral inferior relations
Coils of the jejunum
Course of the fourth part of the duodenum
2.5 cm long
It runs upwards on or immediately to the left of the aorta, up to the upper border of the second lumbar vertebra, where it turns forwards to become continuous with the jejunum at the duodenojejunal flexure
Peritoneal relations of the fourth part of the duodenum
Mostly retroperitoneal being covered with peritoneum only anteriorly
Fourth part of the duodenum: Visceral anterior relations
Transverse colon
Transverse mesocolon
Lesser sac
Stomach
Fourth part of the duodenum: Visceral posterior relations
Left sympathetic chain
Left renal artery
Left gonadal artery
Inferior mesenteric vein
Fourth part of the duodenum: Visceral lateral relations
To the right:
Attachment of the upper part of the root of the mesentery
To the left:
Left kidney
Left ureter
Fourth part of the duodenum: Visceral superior relations
Body of pancreas
What is the suspensory muscle of the duodenum/ligament of Treitz?
Fibromuscular band
Suspends and supports the duodenojejunal flexure
Normally, its contraction increases the angle of the duodenojejunal flexure
Location of the Suspensory Ligament of Treitz?
Arises from the right crus of the diaphragm, close to the right side of the oesophagus, passes downwards behind the pancreas, and is attached to the posterior surface of the duodenojejunal flexure and the third and fourth parts of the duodenum
Arterial supply of the duodenum?
Up to major duodenal papillae: Supplied by the superior pancreaticoduodenal artery
Below major duodenal papillae: Supplied by inferior pancreaticoduodenal artery
Venous drainage of duodenum?
Veins of the duodenum drain into the splenic, superior mesenteric and portal veins
Lymphatic drainage of duodenum?
Pancreaticoduodenal nodes
Hepatic nodes
Coeliac nodes
Cisterna chyli
Nerve supply of duodenum
Sympathetic nerves: T9 and T10
Parasympathetic nerves: Vagus
What is the duodenal cap?
A triangular shadow demarcating the first part of the duodenum in a skiagram taken after eating a barium meal
Common location for peptic ulcer formation in duodenum?
First part of duodenum because of exposure to acidic contents of the stomach
