Structures and Organs of the Digestive Tract Flashcards
Esophagus
Approximately 25 cm.
Long fibromuscular tube connecting the pharynx to the stomach.
Upper oesophageal sphincter: Junction pharynx - oesophagus.
Lower oesophageal sphincter: Junction stomach - oesophagus.
Prevent entry of air and reflux of gastric content.
Anatomical Relations of the Esophagus - Cervical
Anterior: Trachea, thoracic duct, thyroid gland.
Posterior: Vertebral column, longus colli.
Lateral: Lobes of thyroid gland.
Anatomical Relations of the Esophagus - Thoracic
Anterior: - Trachea - Left main bronchus - Pericardium - Left atrium Posterior: - Bodies of thoracic vertebrae - Thoracic duct - Descending thoracic aorta. Right: - Right mediastinal pleura Left: - Left mediastinal pleura - Left subclavian artery - Aortic arch - Thoracic duct
Anatomical Relations of the Esophagus - Abdominal
Crosses the diaphragm
Anterior: Posterior surface of the left lobe of the liver.
Posterior: Left crus of the diaphragm
Lateral: left and right vagus nerve
Esophagus Physiological Constrictions
Food/objects most likely to become stuck - Arch of aorta - Bronchus (left main stem) - Cricoid cartilage - Diaphragmatic hiatus ABCD
Esophagus Innervation and Blood supply
Innervation: Oespageal plexus
Blood supply: Esophageal branches of the thoracic aorta, azygos.
The Stomach
Intraperitoneal organ. Between esophagus and duodenum. - Lesser and greater curvature Anatomical division: - Cardia - Fundus - Body - Pylorus
Cardia (Stomach)
Superior opening of stomach at T11 level.
Junction with esophagus, food comes thorugh.
Fundus (Stomach)
Superior and left of the cardia
Body
Large central portion inferior to fundus.
Pylorus
Connects to duodenum.
Divided into pyloric antrum, pyloric canal, pyloric sphincter.
Greater Curvature (Stomach) + blood supply
Convex
Lateral border
Short gastric arteries and the right and left gastro-omental arteries supply branches to greater curvature.
Lesser Curvature (Stomach) + blood supply + ligament
Shorter and concave
Medial surface
Gives attachment to hepatogastric ligament (connects to liver)
Supplied by left gastric artery and right gastric branch of hepatic artery.
Anatomical Relations of the Stomach
Anterior: Diaphragm, liver (left lobe), and anterior abdominal wall.
Posterior: Omental bursa (lesser sac), pancreas, left kidney and adrenal gland, spleen, and splenic artery.
Superior: Esophagus and diaphragm.
Inferior and lateral: Transversal mesocolon.
Innervation of Stomach
Parasympathetic nerve: anterior and posterior vagal nerve.
Sympathetic nerve: T6-T9 spinal cord segments and passes to the coeliac plexus.
Vascularization of Stomach
Highly vascularized.
- Coeliac trunk
- Right and left gastric arteries
- Right and left gastro-omental arteries
- Right and left gastric veins
- Right and left gastro-omental veins
Small Intestine
6,5 m
Extends from the pylorus of the stomach to the ileocaecal junction.
- Duodenum: most proximal, retroperitoneal!
- Jejunum, Ileum: distal two parts, intraperitoneal!
Superior Duodenum
Spinal level L1
The cap
Connected to the liver by the hepatoduodena ligament
Descending Duodenum
L1-L3
Curves around the head of the pancreas
Posterior to transverse colon and anterior to right kidney
Major duodenal papilla: opening where bile and pancreatic secretion to enter from the ampulla of vater
Inferior Duodenum
L3
Crosses over the inferior vena cava and aorta
Supports lower part of pancreas
Ascending Duodenum
L3-L2
Curves anteriorly to join the jejunum
Sharp turn: duodenojejunum flexure
Anatomical Relations of Duodenum
- Head of pancreas in the curve
- Posterior: abdominal aorta, inferior vena cava, bile duct, right kidney, ureter and L3 vertebra,
- Anterior: Superior mesenteric artery/vein, gallbladder, right lobe of liver.
Jejunum
+/- 2,5 m
Begins at the duodenojejunal flexure
Ileum
+/- 3 m
Ends at the ileocaecal junction.
Invaginates into the caecum to form the ileocaecal valve.
Blood Supply of Duodenum
Gastroduodenal artery
Inferior pancreaticoduocenal artery
Veins follow the major arteries and drain into the hepatic portal vein.
Blood Supply of Jejunum and Ileum
Superior mesenteric artery
Venous drainage in the superior mesenteric vein.
Large Intestine/Colon
\+/- 1,5 m Caecum to anal canal Colon divided in four parts: - Ascending - Transverse - Descending - Sigmoid Covers the square shape of the abdomen.
Cecum
Most proximal in the right iliac fossa of the abdomen.
Intraperitoneal
Appendix: lymphoid pouch
Connected by meso-appendix.
Ascending Colon
Retroperitoneal
Meets the right lobe of the liver and turns 90°
Transverse Colon
Intraperitoneal
Extends from the right colic flexure to the spleen.
Points 90° inferiorly
Attached to the diaphragm by the phrenicocolic ligament.
Descending Colon
Retroperitoneal
After left colic flexure
Anterior to left kidney
Sigmoid Colon
Left lower quadrant
Extending from left iliac fossa at the level of S3 vertebra.
S-Shape
Anatomical Relation of Ascending Colon
Anterior: - Small intestine - Greater omentum - Anterior abdominal wall Posterior: - Iliacus and quadratus lumborum - Right kidney
Anatomical Relations of Transverse Colon
Anterior: - Greater Omentum - Anterior Abdominal wall Posterior: - Duodenum - Head of pancreas - Jejunum and ileum
Anatomical Relations of Descending Colon
Anterior: - Small intestine - Greater omentum - Anterior abdominal wall Posterior: - Iliacus and quadratus lumborum - Left kidney
Anatomical relations of Sigmoid Colon
Anterior: - Urinary bladder - Uterus and upper vagina Posterior: - Rectum - Sacrum - Ileum
Blood Supply of Colon
Ascending: - Superior mesenteric artery - Ileocolic and right colic arteries Transverse: - Right, middle and left colic arteries Descending: - Inferior mesenteric artery Sigmoid: - Sigmoid arteries
Rectum
Last digestive part Most distal, begins at S3 level. 12-16 cm divided in 3 parts: - Upper 1/3: Intraperitoneal - Middle 1/3: Retroperitoneal - Lower 1/3: No peritoneum (better for preventing infection) Terminates into anal canal.
Rectum Flexures
Sacral flexure
Anorectal flexure
Ampulla: final segment of rectum
Diaphragmatic Surface of Liver
Anterosuperior surface
Smooth and convex
Visceral Surface of the Liver
Posterioinferior surface
Covered with peritoneum except fossa of gallbladder and porta hepatis.
Irregular and flat.
Which segments is the visceral surface of the liver in contact with?
- Right kidney
- Right adrenal gland
- Right colic flexure
- Transverse colon
- First part of duodenum
- Gallbladder
- Esophagus
- Stomach
Falciform Ligament of the Liver
Attaches anterior surface of liver to anterior abdominal wall.
Anatomical division between left and right lobes.
Coronary Ligament of the Liver
Attaches superior surface of liver to inferior surface of diaphragm.
Boundaries of the bare area of the liver (not covered by peritoneum, more affected by disease).
Triangular Ligaments of the Liver
Formed by anterior and posterior layer of coronary ligament on each side of liver, attaching the right and left lobes to the diaphragm.
Caudate Lobe of the Liver
Located on upper aspect of the visceral surface. Superior - Posterior.
Between inferior vena cava and a fossa produced by ligamentum venosum.
Quadrate Lobe of the Liver
Located on the lower aspect of the visceral surface. Inferior - posterior.
Between gallbladder and fossa produced by ligamentum teres.
Vascularization of the Liver
Hepatic artery proper - 25% Hepatic portal vein - 75% - Supplies liver with low oxygenated blood, with nutrients absorbed in small intestine. - Drainage
Anatomical Relations of the Liver
Superior: Diaphragm
Anterior: Ribs (7-11th), anterior abdominal wall
Posterior-inferior: Esophagus, right kidney and adrenal gland, right colic flexure, lesser omentum, duodenum, gallbladder, stomach.
Gallbadder
Gastrointestinal organ
between the inferior right lobe and quadrate lobe.
Intraperitoneal
Concentrate and store bile produced by liver.
Digestion of fats
Fundus of the Gallbladder
Distal portion
Projects into the inferior surface of the liver in the mid-clavicular line.
Body of the Gallbladder
Largest part of the gallbladder
Lies adjacent to the posteioinferior aspect of the liver, transverse colon and superior part of duodenum.
Neck of the Gallbladder
continuous with the cystic duct, leading into the biliary tree.
Biliary Tree
Series of gastrointestinal ducts allowing newly synthesized bile from the liver to be concentrated and stored in the gallbladder.
- Common hepatic duct (liver)
- Cystic duct
- Pancreatic duct
Cystic duct of the Biliary Tree
Allows bile to flow in and out of the gallbladder.
Forms the common bile duct (with common hepatic duct).
Pancreatic Duct of the Biliary Tree
Forms the hepatopancreatic ampulla of vater with the common bile duct.
Empties in the duodenum.
Spleen
Under cover of the diaphragm and the ribcage.
Intraperitoneal
Function: Blood filter!
Connected to the stomach and kidney by parts of the greater omentum.
Gastrosplenic ligament of the Spleen
Spleen to the greater curvature of the stomach.
Splenorenal Ligament of the Spleen
Hilum of the spleen to the left kidney.
Anatomical Relations of the Spleen
Anterior: Stomach
Posterior: Diaphragm, left lung, ribs 9-11.
Inferior: Left colic flexure (splenic flexure).
Medial: Left kidney, tail of pancreas.
Pancreas
Retroperitoneal (except tail)
Abdominal glandular organ
Function:
- Digestive - Exocrine: pancreatic juice to the biliary tree.
- Hormonal - Endocrine: Blood levels of glucose.
Head of the Pancreas
The widest part of the pancreas.
Uncinate Process of the Pancreas
A projection arising from the lower part of the head and extending medially to lie beneath the body of the pancreas.
Neck of the Pancreas
Located between the head and the body of the pancreas.
Body of the Pancreas
Centrally located, crossing the midline of the human body to lie behind the stomach and to the left of the superior mesenteric vessels.
Tail of the Pancreas
Left end of the pancreas that lies within close proximity to the hilum of the spleen. Only part that is intraperitoneal.
Anatomical Relations of the Pancreas
Anterior: - Stomach - Duodenum: 1st part - Transverse mesocolon Lateral Right: - 2nd part of duodenum, descending - Ampulla of Vater Posterior: - Common bile duct - Spleen - Aorta and inferior vena cava pass - The superior mesenteric artery
