Digestive - Accessory Organs PDF

Digestive: Accessory Organs YBOD200 Mr J Naidoo  Learning Objectives Identify, describe and discuss the position and relational anatomy of the accessory organs: o Pancreas o Liver o Gallbladder o Spleen Identify, describe and discuss in detail the speci...

Digestive: Accessory Organs YBOD200 Mr J Naidoo  Learning Objectives Identify, describe and discuss the position and relational anatomy of the accessory organs: o Pancreas o Liver o Gallbladder o Spleen Identify, describe and discuss in detail the specific characteristics of the: o Pancreas ▪ Head, body, tail ▪ Endocrine and exocrine portions ▪ Compositions per region o Liver ▪ Liver lobes ▪ Ligaments associated with liver ▪ Relation to the gallbladder  Learning Objectives Identify describe and discuss blood supply, innervation and lymph drainage of the accessory organs Clinical relevance of the anatomy of the accessory organs Liver  Liver Largest visceral organ of body Primarily in right hypochondrium and epigastric region, extends to left hypochondrium Has two surfaces: o Diaphragmatic surface: in anterior, superior, and posterior directions o Visceral surface: in inferior direction Functions in metabolism, synthesis of bile and prothrombin, excretion, glycogen storage and protection via antibody formation  Diaphragmatic Surface Smooth and domed Lies against inferior surface of diaphragm Associated with subphrenic and hepatorenal recesses o Subphrenic recess – separates liver from diaphragm, divided into left and right areas by falciform ligament o Hepatorenal recess – part of peritoneal cavity on right side, between liver and right kidney and suprarenal gland These two recesses are continuous anteriorly  Visceral Surface Covered with visceral peritoneum, except in fossa for gallbladder and at porta hepatis (gateway to liver) Several related structures: o Oesophagus o Right anterior part of stomach o Superior part of duodenum o Lesser omentum o Gallbladder o Right colic flexure o Right transverse colon o Right kidney o Right suprarenal gland  Porta hepatis Deep transverse fissure between quadrate and caudate lobes Point of entry into liver for hepatic arteries and portal vein Point of exit for hepatic ducts Attachment site for lesser omentum o Surrounds structures of porta hepatis Hepatic ducts lie anterior to portal vein o Hepatic arteries usually lie between two  Falciform Ligament Attaches liver to anterior abdominal wall On posterior surface, divides liver into right and left lobes Ligamentum venosum o On posterior surface of liver o Borders caudate lobe on superior margin o Remnant of ductus venosus Ligamentum teres (also known as round ligament of liver) o On posterior surface of liver o Found in interlobar notch o Borders quadrate lobe on inferior margin o Remnant of umbilical vein  Ligaments Hepatogastric Ligament: Between liver and stomach Hepatoduodenal Ligament: Between liver and duodenum Right and Left Triangular Ligaments: Attach liver to diaphragm Anterior and Posterior Coronary Ligaments: Attach liver to diaphragm Enclose bare area of liver (area not covered by peritoneum)  Bare Area Part of liver free from peritoneum Anterior boundary: o Indicated by anterior coronary ligament Posterior boundary: o Indicated by posterior coronary ligament Coronary ligaments come together laterally to form right and left triangular ligaments  Lobes Falciform ligament divides liver into right and left lobes RIGHT LOBE: Largest Approximately ⁵/₆ of liver LEFT LOBE: Flattened from above downwards Approximately ¹/₆ of liver Posteriorly, fissure for ligamentum venosum and ligamentum teres divide liver into two lobes  Lobes QUADRATE LOBE: Boundaries: o Left: fissure for ligamentum teres o Right: fossa for gallbladder Functionally associated with left lobe CAUDATE LOBE: Boundaries: o Left: fissure for ligamentum venosum o Right: groove for inferior vena cava Functionally separate from both right and left lobes  Vasculature of Liver Hepatic artery, hepatic portal veins, hepatic veins Hepatic artery and portal vein ascend in lesser omentum to porta hepatis Common hepatic duct and lymphatic vessels descend in lesser omentum Hepatic veins leave liver on its posterior surface to drain into IVC Lymphatic drainage: caval, hepatic, paracardial and coeliac nodes, Some lymph from coronary ligaments drain into thoracic duct directily Functional Lobes of Liver  Functional Lobes Division into eight functional segments, based on distribution of portal venous branches in parenchyma Divided into four portal sectors: Right anterior, right posterior, left medial, left lateral Division is due to four main hepatic veins Three hepatic veins lie between segments as intersectoral veins Veins lie in main fissures which divide sectors Three minor fissures (umbilical, venous, Rouvieres sulcus), appear as physical clefts on liver surface Functional Lobes of Liver Caudate lobe is Segment I; thereafter, segments labelled in clockwise fashion (on anterior view). Gallbladder  Gallbladder Pear-shaped sac, lying between right and quadrate lobes 7-10cm long, 3cm broad, 30-50ml capacity Receives, concentrates and stores bile from liver Fundus – rounded end, projects from inferior border of liver, in angle between rectus abdominus and 9th costal cartilage Body – lies against transverse colon and superior part of duodenum, continuous with neck at right end of porta hepatis Neck – narrow part with mucosal folds which forms spiral fold which prevents obstruction to outflow/inflow of bile  Gallbladder CYSTIC DUCT: 3-4cm long, begins at neck of gallbladder Joins common hepatic duct at an angle to form bile duct Mucous membrane forms crescenteric folds BILE DUCT: Cystic duct and common hepatic duct join 8cm long Runs supraduodenal, retroduodenal, infraduodenal and then intraduodenal Opens into major duodenal papilla  Neurovasculature of Gallbladder ARTERIAL SUPPLY: Gallbladder supplied by cystic artery, a branch of right hepatic artery Bile duct supplied by posterior superior pancreaticoduodenal artery VENOUS DRAINAGE: Cystic veins, portal veins, hepatic veins LYMPHATICS: Cystic node, hepatic node, upper pancreaticosplenic node NERVE SUPPLY: Cystic plexus of nerves, right phrenic nerves Pancreas  Pancreas Posterior to stomach, extends across posterior abdominal wall between duodenum and spleen, at L1 J-shaped, 15-20cm long Retroperitoneal, except for a small part of tail Structurally: Branched acinar gland wrapped in delicate connective tissue Healthy pancreas is yellow, with a soft-to-firm consistency and lobulated surface  Pancreas Head: lies within C-shaped concavity of duodenum Uncinate process: projects from lower part of head, lies posterior to superior mesenteric vessels Neck: anterior to superior mesenteric vessels, splenic and superior mesenteric veins join to form portal vein posterior to neck of pancreas Body: elongated and extends from neck to tail of pancreas Tail: passes between layers of splenorenal ligament  Pancreatic Duct Begins in tail of pancreas, turns inferiorly at head of pancreas o Joins bile duct in lower part of head Hepatopancreatic ampulla – pancreatic and bile ducts join o Enters second part of duodenum at major duodenal papilla Surrounding the ampulla is sphincter of ampulla (collection of smooth muscles) ACCESSORY PANCREATIC DUCT o Empties into minor duodenal papilla just above major duodenal papilla (Usually communicates with main pancreatic duct)  Arterial Supply of Pancreas Gastroduodenal artery from common hepatic artery o Anterior superior pancreaticoduodenal artery o Posterior superior pancreaticoduodenal artery Inferior pancreatic artery from splenic artery o Dorsal pancreatic artery o Great pancreatic artery Inferior pancreaticoduodenal artery from superior mesenteric artery o Anterior inferior pancreaticoduodenal artery o Posterior inferior pancreaticoduodenal artery  Venous & Lymphatic Drainage of Pancreas Portal vein, superior mesenteric vein, splenic vein Superior and inferior pancreaticoduodenal veins o Head and uncinate process Splenic vein o Drain body and tail of pancreas LYMPHATIC DRAINAGE: quite extensive Starts at interlobular septa within gland, then larger lymphatic vessels follow paths of arteries o Tail and body – nodes along splenic artery o Head and neck – pre-aortic nodes Spleen  Spleen Develops as part of vascular system in dorsal mesentery Located in left hypochondrium, against diaphragm at Rib 9 – Rib 10 Wedge-shaped organ, between fundus of stomach and diaphragm Functions in phagocytosis, haematopoiesis, immune response and in storage of red blood cells Splenic hilum o Entry point for splenic vessels o Tail of pancreas related to this area Anterior end: expanded and reaches midaxillary line Posterior end: rounded, rests on upper pole of left kidney  Spleen Superior border – notched on anterior end – splenic notch Inferior border – rounded Impressions on visceral surface: o Gastric o Renal o Colic o Pancreatic Gastrosplenic ligament – Attached to greater curvature of stomach, contains short gastric and gastro-omental vessels Splenorenal ligament – Attached to left kidney, contains splenic vessels  Vasculature of Spleen ARTERIAL SUPPLY: Splenic artery, gives off a left gastro-omental artery VENOUS DRAINAGE: Splenic vein, joins superior mesenteric vein to form portal vein. LYMPHATICS: Pancreaticosplenic nodes NERVE SUPPLY: Coeliac plexus – sympathetic innervation. Innervation of Accessory Organs  Innervation of Accessory Organs LIVER: Parenchyma supplied by the hepatic plexus o Sympathetic: coeliac plexus o Parasympathetic: vagus nerve fibres Referred pain o Epigastric region for parenchyma o Right shoulder for diaphragmatic surface of liver o Localized ‘somatic’ pain for fibrous capsule of liver SPLEEN Sympathetic: coeliac plexus – sympathetic supply dominant Parasympathetic: vagus nerve Referred pain is in epigastric region  Innervation of Accessory Organs GALLBLADDER Sympathetic and sensory fibres: coeliac plexus Parasympathetic fibres: vagus nerve (which stimulates contraction of gallbladder). Referred pain o Right hypochondriac and epigastric regions – can radiate to back, inferior to right scapula PANCREAS Sympathetic: Extra-pancreatic and intra-pancreatic plexuses of autonomic nerves Parasympathetic: Vagal efferents reach pancreas via hepatic, gastric and coeliac branches of vagus nerve Referred pain localized to lower thoracic spine o Due to inflammation of pancreas involving retroperitoneum which is innervated by somatic nerves Clinical Relevance  ERCP Endoscopic retrograde cholangiopancreatography Can be used to remove obstructing gallstones within biliary tree Combines endoluminal endoscopy with fluoroscopy to diagnose and treat problems in biliary and pancreatic ducts Endoscope is put through oesophagus and stomach to second part of duodenum where major duodenal papilla is Bile or pancreatic duct is then cannulated and contrast is put into either bile duct (cholangiogram) or pancreatic duct (pancreatogram)  Splenomegaly Spleen is an organ of reticuloendothelial system – involved in haematopoiesis and immune system Diseases such as leukaemia or lymphoma, may produce generalized lymphadenopathy and enlargement of the spleen – splenomegaly Spleen enlarges during normal physiological functioning Splenomegaly may also occur due to increased venous pressure due to heart failure, portal hypertension or splenic vein thrombosis Enlarged spleen is prone to rupture That’s All Folks! For any queries or questions please feel free to contact me: [email protected]  RESOURCES Grays Anatomy for Students, 6th Edition Chapter 4 – Abdomen Abdominal Viscera https://www.clinicalkey.com/student/content/book/3-s2.0- B9780323934237000046#hl0003362 Grays Anatomy – The Anatomical Basis of Clinical Practice, 42nd Edition Chapter 66 – 69 Liver, Gallbladder, Pancreas, Spleen https://www.clinicalkey.com/student/content/book/3-s2.0- B9780702077050000665#hl0000171