Duodenum

The duodenum ( German to the duodenum) is the first short section of the small intestine. He is the man about 30 cm long, which is about 12 finger-widths corresponding to ( hence the name). Its shape corresponds to the appearance of a human, C's, with four-footed mammals like an open forward horseshoe. He circled the head of the pancreas and is adherent to the abdominal cavity on the back wall. In the duodenum the bile flow leading transition and the excretory duct of the pancreas.

Anatomy

The initial part of the duodenum is called in humans as the superior part, in animals as Pars cranialis. It rises at the pylorus ( the "gatekeeper " of the stomach ), is about the hepatoduodenal ligament to the liver connected (see the lesser omentum ) and is the only section within the peritoneum ( intraperitoneal). In humans, the superior part is a duodenal ampulla (clinically: duodenal bulb ) expanded and fixed the transition to the jejunum through the suspensory ligament ulcer. In ungulates, the Pars cranialis S-shaped curved ( sigmoid ) and rises to the right abdominal wall to the porta hepatis.

The superior part ends with a bend ( flexure duodenal superior or cranial ) consists in the descending part ( descending part ) away and from now on are the remaining portions of the duodenum in humans secondarily retroperitoneal. The initial part of the descending part in mammals has a shallow mucosal fold ( plica longitudinalis duodenal ), on which the major duodenal papilla (syn. papilla of Vater ), a survey with the common mouth of the pancreatic duct and the common bile duct, is seated. The descending part pulls down where the duodenum in duodenal flexure used inferior or caudal again. This lower portion is also referred to as a horizontal part, in animals as transverse part. The duodenum is now continuing as an ascending part ( pars ascendens ) and goes to the duodenojejunal flexure ( duodenum - jejunum - bending) into the jejunum.

In many cases, above the usual bile estuary, the major duodenal papilla, open another passage from the pancreas ( pancreatic ) into the minor duodenal papilla. This transition is referred to as the accessory pancreatic duct.

Vascular supply

Arterial the duodenum via the gastroduodenal artery ( from the common hepatic artery from the celiac artery ) is supplied, the artery and the artery supraduodenalis pancreaticoduodenales the superior anterior and posterior releases in their further course. Especially the last two arteries are responsible for the bulk of the supply of the duodenum. This form anastomoses with branches of the vascular artery inferior pancreaticoduodenal, which originates from the superior mesenteric artery.

Venous are the venae pancreaticoduodenales superior and inferior, and whose branches responsible for drainage. They open variable either in the superior mesenteric vein or directly into the portal vein ( portal vein hepatis ).

Histology

The duodenum shows the typical for all the organs of the gastrointestinal tract structure. This is divided into mucous membrane ( tunica mucosa ), submucosa, muscular layer (tunica muscularis ) and tunica adventitia ( retroperitoneal ) and serosa ( intraperitoneal).

The mucous membrane is divided from the inside ( the intestinal lumen ) to the outside in:

• Epithelial layer consists of columnar epithelium which is mainly transmitted from microvilli enterocytes. Further occur goblet cells, Paneth cells, enteroendocrine cells, and M cells.
• Lamina propria of loose connective tissue with a lamina muscularis mucosae, a circularly arranged layer of smooth muscle that allows a fine adjustment to the intestinal contents. It represents the boundary to the underlying submucosa dar.

The submucosa consists of loose connective tissue and serves as a sliding layer between mucosa and muscle layer. It also contains blood vessels, lymph vessels, the submucosal plexus and as a special so-called Brunner's glands of the duodenum ( duodenal glands ).

The muscle layer is divided into an inner ring and an outer longitudinal muscle layer ( Stratum Stratum circulare and longitudinal ). The object of the muscles is the generation of intestinal peristalsis, wherein a contraction of the annular layer which restricts a contraction of the intestinal lumen, and the longitudinal layer shortens the intestine. Between circular and longitudinal muscle layer located in a thin layer of connective tissue myenteric vessels and nerve fibers of the plexus.

Investigation

The investigation of the duodenum should be some value in the rule with a flexible endoscope, because at the same time tissue samples ( biopsies) can be taken. This is known as duodenoscopy. Most of the stomach ( gastroduodenoscopy ) and the adjacent part of the small intestine ( Duodenojejunoskopie ) is also investigated. By means of a duodenal tube, the duodenal contents to test for pathogens or to immobilize derived or a diet bypassing the chewing and swallowing disorders and stomach are possible.

Diseases

The duodenum is medically particularly through the right common duodenal ulcer ( duodenal ulcer ) is important. About 2 % of the population get such ulcer during their lifetime.

Other conditions are:

• Duodenal
• Duodenitis
• Duodenal
• Duodenal atresia
• Duodenaltumoren: duodenal