Duodenum : Human Anatomy
Duodenum- Duodenal Relations-The first part of the duodenum-second part of the duodenum-The third part of the duodenum-The fourth part of. The duodenum is the first of the three parts of the small intestine and is directly attached to the pylorus Relations of second part of duodenum. For illustrative purposes, the 25 cm long duodenum is split into 4 parts: Superior ( first) part, 5 cm (2 inches) long.
The junction between the embryological foregut and midgut lies just below the major duodenal papilla.
Human Anatomy: Anatomy of the Duodenum
It begins at the inferior duodenal flexure and passes transversely to the left, passing in front of the inferior vena cavaabdominal aorta and the vertebral column. The superior mesenteric artery and vein are anterior to the third part of duodenum.
Fourth part[ edit ] The fourth part, or ascending part, of the duodenum passes upward, joining with the jejunum at the duodenojejunal flexure. The fourth part of the duodenum is at the vertebral level L3, and may pass directly on top, or slightly to the left, of the aorta. The transition between these sources is important as it demarcates the foregut from the midgut. Proximal to the 2nd part of the duodenum approximately at the major duodenal papilla — where the bile duct enters the arterial supply is from the gastroduodenal artery and its branch the superior pancreaticoduodenal artery.
Distal to this point the midgut the arterial supply is from the superior mesenteric artery SMAand its branch the inferior pancreaticoduodenal artery supplies the 3rd and 4th sections. The superior and inferior pancreaticoduodenal arteries from the gastroduodenal artery and SMA respectively form an anastomotic loop between the celiac trunk and the SMA; so there is potential for collateral circulation here.
The venous drainage of the duodenum follows the arteries. Ultimately these veins drain into the portal systemeither directly or indirectly through the splenic or superior mesenteric vein.
Parts and Relations For illustrative purposes, the 25 cm long duodenum is split into 4 parts: Superior first part, 5 cm 2 inches long. Descending 2nd part, 7.
Horizontal third part, 10 cm 4 inches long. Ascending fourth part, 2. First Part Course It starts at the pylorus, enters upward, backward, and laterally to the right side of the vertebral column to get to the neck of the gallbladderwhere it bends downward superiorduodenal flexure to become constant with the 2nd part of the duodenum. Features It develops from the foregut. Particular features of the very first part of the duodenum are: Only part first inch of the very first part that is intraperitoneal for this reason freely movable.
Duodenum | Radiology Reference Article | bestwebdirectory.info
Only part supplied by end arteries. Only part that is devoid of circular mucus folds. Quadrate lobe of the liver and gallbladder. Portal vein, gastroduodenal artery, and common bile duct CBD. Epiploic foramen being divided from it by the portal vein and bile duct. Head and neck of the pancreas.
Features Its upper half grows from the foregut and lower half from the midgut. It is located behind the transverse mesocolon. It gets the bile duct, the main and accessory pancreatic ducts. Gallbladder and right lobe of the liver, transverse colon, transverse mesocolon commencementand coils of the small intestine.
Right kidney and right renal vessels, right edge of the inferior vena cava IVCand right psoas major muscle. Head of the pancreas. From below upward, ascending colon, right colic flexure, and right lobe of the liver. Third Part Course It runs horizontally to the left, across the lower part of the body of L3 vertebra, crosses in front of IVC, and after that takes a smooth curve upward to eventually become constant with the ascending part of the duodenum. Root of the mesentery, superior mesenteric vessels, and coils of the jejunum.
Right psoas major, right ureter, IVC, abdominal aorta, and right gonadal vessels. Head of the pancreas with its uncinate process.
Coils of the jejunum. Fourth Part Course It runs upward, on or immediately to the left of the abdominal aortafrom the ending of the 3rd part to the upper border of the L2 vertebra where it turns forward ventrally to become constant with the jejunum duodenojejunal flexure. Transverse colon and transverse mesocolon. Left psoas major muscle, left sympathetic chain, left gonadal vessels, and inferior mesenteric vein.
Body of the pancreas. On to the left: Left kidney and left ureter. On to the right: Upper part of the root of mesentery. Inside of The Duodenum Being a part of the small intestine, the mucous membrane of the duodenum presents circular folds valves of Kerckringnevertheless they start in the 2nd part and become large and closely set below the level of the major duodenal papilla.
Along with this, the inside of the 2nd part of the duodenum presents the following special features: On its peak starts the common hepatopancreatic duct created by the unification of bile and main pancreatic ducts. The accessory pancreatic duct starts on its peak.
Arch of plica semicircularis: The plica semicircularis creates an arch above the major duodenal papilla like a hood cf. Its upper end is connected on to the right crus of the diaphragm and the lowerend connected on to the posterior surface of the duodenojejunal flexure. Striated muscle fibres in the upper part. Elastic fibres in the middle part.
Non-striated muscle fibres in the lower part. The ligament of Treitz fixes the duodenojejunal flexure and keeps it from being dragged down by the weight of loops of the small intestine. It also acts as a significant milestone in the radiological diagnosis of incomplete rotation or malrotation of the small intestine.
Points to be noticed Occasionally, the ligament of Treitz may kink the duodenojejunal flexure and might cause partial intestinal obstruction. The ligament of Treitz if short the duodenum will be O-shaped, and if long the duodenum will be inverse J-shaped. Therefore, 3 contours of the duodenum are recognized, viz.
Duodenal Recesses Fossae In the region of duodenojejunal junction, small pocket like pouches of peritoneum termed duodenal recesses do take place. All these are occasionally accountable for strangulated retroperitoneal hernia.