Dr. Suhasini P tayde Associate prof Department of Anatomy Introduction  The term ‘’ is a Latin correction Greek word ‘Do-deka-dactulos’ which means that the length of duodenum is equal to the breadth of twelve fingers.  Duodenum is proximal dilated and fixed part of and is devoid of mesentry.  It has a ‘C ‘ shaped curve, which encloses the head of pancreas Duodeum lies entirely above the level of umbilicus, oppsite I,II, III Lumbar vertebrae  Duodenum is 25 cm long & subdivided into 4 parts 1. First or upper part-5 cm 2. Second or vertical part-8-10 cm 3. Third or horizontal part -10 cm 4. Fourth or ascending part- 2.5 cm First part  It extends from to the superior duodenal flexure .  It is directed upwards, backwards & to the right.  Relations-  Anteriorly – it is covered with peritoneum of greater sac and related to 1. Quadrate lobe of liver 2. Neck and body of gall bladder  Posteriorly mostly non-peritoneal except close to pyloric part where it is lined by peritoneum of lesser sac Related to- 1. Portal vein , , & Gastro-duodenal artery 2. Inferior vena cava Superiorly  Eploic foramen Inferiorly- head and neck of pancreas

Peculiarities of 1st part  It is the most movable part of duodenum  It is supplied by end arteries  It is devoid of circular mucous fold  A triangular radio-opaque shadow known as a duodenal cap may be observed in first part after barium meal. It may be distorted in peptic ulcer or in malignant growth Second part  It begins at superior duodenal flexure opposite I Lumbar vertebra  It passes vertically downwards in front of hilum of right kidney along the right side of vertebral column  It ends at inferior duodenal flexure, opposite lower border of III Lumbar vertebra, where it bends to the left side and continuous with 3rd part. Relations of 2nd part  Its anterior surface covered with peritoneum except near the middle, where it is crossed by  Visceral relations –Anteriorly 1. Duodenal impression of right lobe of liver, sometimes fundus & body of gall bladder. 2. Few coils of

 Posteriorly-  It is entirely non-peritoneal  Related to – 1. Anterior surface of right kidney, close to hilum 2. Right renal vessels 3. Pelvis of right ureter 4. Right psoas major muscle 5. Right edge of inferior vena cava 6. Sometimes part of right supra-renal gland Relations of 2nd part  Laterally Right colic flexure  Medially- 1. head of pancreas 2. Ventral & dorsal anastomoses of superior & inferior pancreatico-duodenal vessels 3. Bile duct & main ,they pierce the duodenal wall separately, they unite to form ampulla of vater which opens on the summit of 4. Accessory pancreatic duct is situated about 2 cm above the major papilla Interior of 2nd part, 1. It shows circular folds 2. Major duodenal papilla It is conical projection arising from postero-medial, wall , situated 8-10 cm distal to the pylorus It presents single orifice through which bile duct & pancreatic duct open 4. It is small conical projection situated 2cm above the major papilla Accessory pancreatic duct opens on its summit 5. Plica-semicircularis –it arches above the major papilla

6. Plica-longitudinalis-it is vertical fold extending downwards from major papilla 3rd part  It is about 10 cm extend from inferior duodenal flexure to front of aorta at the level of III Lumbar vertebra  Relations Anteriorly- It is crossed by superior mesenteric vessel and root of mesentery

Posteriorly-  Right psoas major  Right ureter  Inferior vena cava  Right gonadal vessels  Abdominal aorta  Origin of inferior mesenteric artery

 Superiorly Head of pancreas with uncinate process

 Inferiorly Coils of jejunum 4th part  It is about 2.5cm and extend from front of aorta to the duodeno-jejunal flexure.  Relations Anteriorly- mostly covered with peritoneum  Transverse colon & meso-colon  , lesser sac

Posterioly –  Left crus of diaphragm  Left psoas major, left sympathetic chain  Left renal vessels  Left gonadal vessels  Left supra-renal vein  Inferior mesenteric vein

 Right side Uncinate process of pancreas

 Left side Left kidney & ureter

 Superiorly Body of pancreas Arterial supply  1st part Unlike the rest of duodenum , it is supplied by end arteries as follows- 1. Supra-duodenal branch of gastro-duodenal artery (i.e. artery of wilkie ) 2. Sometimes retro-duodenal branch of gastro-duodenal artery – 3. Infra-duodenal branch of right gastro-epiploic artery-it supplies lower margin

 2nd ,3rd & 4th parts are supplied by ventral & dorsal anastomoses of superior & inferior pancreatico-duodenal artery Venous drainage  The veins drain into superior mesentric vein & portal vein. Lymphatic drainage  Lymph vessels drain into the pancreatico-duodenal lymph nodes  Efferent vessels of these nodes drain into the coeliac & superior mesenteric group of pre- aortic lymph nodes Nerve supply  Sympathetic nerves derived from Coeliac and superior mesenteric plexuses  Pre-ganglionic fibres come from T6 to T9 spinal segments  Parasympathetic nerves from vagus Histology  The wall of duodenum presents four coats From outside inwards 1. Serous coat-it is derived from peritoneum and is incomplete 2. Muscular coat-consist of outer longitudinal & inner circular layer of smooth muscles, separated by myenteric plexuses of nerves 3. Submucous coat- consists of loose areolar tissue & contains plexus of blood vessels & lymphatics, Meissner’s plexuses of nerve & duodenal glands of Brunner, these glands are characteristics of duodenum, it screte a fluid rich in bicarbonate ions & an enzyme which activate trypsinogen from the pancreas 4. - consist from within outwards of  Surface epithelium-lined by simple columnar cells, occasional Goblet cells, & is provided with numerous villi  - contains crypts of lieberkuhn which are tubular glands & receive at their bottom openings of Brunner’s glands  Embryology  The mucous membrane of duodenum above the ampulla of vater is developed from endoderm of foregut and rest below the ampulla from midgut.  Musculature from splanchnic layer of lateral plate mesoderm  Primtive duodenum presents a loop with convexity directed ventrally in median plane  The hepato-pancreatic bud arises from this margin at the juction of foregut and midgut, & extend into vetral mesogastrium   The concave margin attached to the posterior body wall by mesoduodenum  Dorsal pancreatic bud arises from this margin & extend backward into mesoduodenum  With the rotation of stomach, duodenum rotates to the right side so that anterior convex margin margin forms lateral border & right surface becomes posterior surface.  II part undergoes axial rotation due to differences in rate of growth of its wall  The hepato-pancreatic bud, appears on postero- medial aspect of II part & dorsal pancreatic bud shifts more ventrally.  Thus duodenum undergoes rotation , fixation to the posterior abdominal wall & axial rotation. Applied Anatomy  I part is vulnerable to the formation of peptic ulcer. There may be severe hemorrhage in peptic ulcer , due to erosion of gastro-duodenal artery which passes behind the I part  II part is most protected from external injury since it is situated behind the forward curvature of the vertebral column in the paravertebral gutter. Bile stones may be impacted on the summit of major papilla producing obstructive jaundice. Annular type of the pancreas sometimes encircles the duodenum. Malignant growth of the pancreatic head produces duodenal obstruction.  III part of duodenum is most vulnerable to external injury because it may be compressed between the vertebral column and a violence through the anterior abdominal wall

 IV part of duodenum is related to a number of peritoneal recesses. A loop of small gut may be herniate into any of the recesses, this may lead to intestinal obstruction.