Med Oradea - Anatomy II - Digestive System - Small Intestine And Abdominal Wall

Has 4 parts

The first and third parts are retroperitoneal

Is situated in the supramezocolic space

Is fixed

Is shaped like a horseshoe with the opening to the left

The duodenal bulb runs from the duodenopiloric incisure to the gallbladder

Has an upper, lower, and duodenojejunal flexure

Presents vertical folds on the interior

The greater duodenal papilla opens in the Vater's ampoule

Has relationships in its 3rd and 4th part with the root of the mezenterum in front (and the transverse colon)

The greater duodenal papilla is in the lower part of a vertical fold

Vertical fold is determined by the Wirsung duct

The pancreatic duct unites with the Santonini duct

Intestinal villi are present at the distal part

Presents 4 coats: serous membrane, muscular membrane, submucous, and mucous

Brunner glands are duodenal glands between the submucous and muscular membrane

Only the second, third, and fourth parts are retroperitoneal

The peritoneal membrane forms lunate folds (duodenal fossas) in the fourth part

The duodenal fossas are called the superior duodenal, inferior duodenal, retroduodenal, and duodeno-jejunal

The liver is in front of the first and second part of the duodenum

The second part of the duodenum has relations behind with the coledoc duct, portal vein, and gastroduodenal artery

The liver is above the second part of the duodenum

Below the first part of the duodenum there is the pancreas, which is also medial to the second part

The inferior vena cava is behind the second and third parts of the duodenum

In its first part, the pancreas below and the liver to the left

In its second part, the liver and ascending colon, laterally

In its third part, the aorta and uterus, behind

In its third part, mesenteric vessels in front

In its fourt part, the left kidney behind and laterally

The gastroduodenal artery is a branch of the common hepatic

The fourth part of the duodenum has the stomach above and the aorta behind and medially

The aorta is behind the second part of the duodenum

The left kidney is lateral to the 3rd (transverse) and 4th (ascending) part of the duodenum

The stomach is above the 3rd and 4th part of the duodenum

The veins of the duodenum go to the portal vein

The duodenum is supplied by the gastroduodenal and superior mesenteric arteries

The superior pancreaticoduodenal artery is from the superior mesenteric artery

The inferior pancreaticoduodenal artery is from the superior mesenteric artery

Lymph drains to the hepatic and celiac lymph nodes

Parasympathetic innervation is from the celiac ganglia

Innervation is partly from thoracic splanchnic nerves

Thoracic splanchnic nerves are parasympathetic nerves which is why they don't synapse in the paravertebral ganglia

Jejunum is fixed, ileum is mobile

Occasionally is partially outside the inframezocolic space

Jejunum and ileum don't have clearly defined limits, but jejunum is about 3/5 and ileum 2/5

Compared to the ileum, jejunum has more circular folds, is bigger, has more blood vessels, and is stronger

Peyer patches are found in the ileum and are lymphatic formations

Together have transversal folds, but only the ileum has vertical folds

In front is the greater omentum

The omentum is also called the epiploon

Behind is the retroperitoneal space and posterior abdominal wall

Below is the bladder, rectum, and uterus (in women)

The ascending and descending colon is lateral

Jejunum and ileum are connected to the posterior abdominal wall by a mesentery

This mesentery has an anterior (right) and posterior (left) surface

The mesentery has an intestinal border behind and a parietal border in front

Jejunum and ileum present circular folds in their mucous layer

Present intestinal villi

Have 4 layers: serous, muscular, submucous, and mucous

The muscular layer is composed of an external circular layer and an internal longitudinal layer

The mucous layer has peyer patches in the ileum

Receive blood from the superior mesenteric artery (a branch of the aorta) and the superior colic artery

The upper mesenteric vein drains them

Lymph goes to apical nodes and from there to cisterna chyli

Celiac and mesenteric plexuses supply innervation

Receive innervation from the vagus nerve via the celiac plexus

The celiac plexus continues to the superior mesenteric plexus which surrounds the superior mesenteric artery

The vagus nerve joins the superior mesenteric plexus

The superior mesenteric plexus comes from the celiac plexus

Is limited in the upper part by the costal arches and xiphoid process

Is limited in the lower part by a line connecting the inferior limit of the iliac crests

When divided into the system of 9 regions, the vertical lines are mid-axillary and the horizontal lines are bicostal and bicrestal

The bicrestal line connects the anterior end of the iliac fossa

The left hypochondriac region is in the second row

The third row has the right and left iliac fossa

The hypogastric region is in the first row

The right and left epigastric regions are in the second row

The umbilical region is in the second row

Serous coat is a visceral peritoneal membrane

Muscular coat has external longitudinal fibers

Has intestinal villi but these are absent in the first part of the duodenum and last part of ileum

Celiac plexus provides sympathetic innervation from the solar plexus