General Arrangement of the Abdomen PDF

RCSI Royal College of Surgeons in Ireland Coláiste Ríoga na Máinleá in Éirinn General Arrangement of the Abdomen Course GIHEP Lecturer Dr. Caroline Curtin Email [email protected] Date 16/09/2024  Learning Outcomes Outline the location...

RCSI Royal College of Surgeons in Ireland Coláiste Ríoga na Máinleá in Éirinn General Arrangement of the Abdomen Course GIHEP Lecturer Dr. Caroline Curtin Email [email protected] Date 16/09/2024  Learning Outcomes Outline the location and arrangement of the major abdominal organs Explain how the peritoneum is arranged within the abdomen, with parietal and visceral layers Describe how the peritoneum is reflected from the wall to viscera to form peritoneal attachments or ligaments Describe how the dorsal and ventral mesogastria are formed with the rotation of the stomach Explain the main abdominal compartments and recesses why these are clinically relevant Abdomen Regions Transpyloric Plane: L1 9th costal cartilage 1/2 way from suprasternal notch to symphysis pubis [1/2 way from xiphoid to umbilicus] linea semilunaris (lat border of rectus) cuts costal margin L1 Relations: The fundus of the gallbladder The end of the spinal cord The pancreatic body Origin of superior mesenteric artery Left and right colic flexure Hila of the kidneys The spleen Abdomen + Peritoneal Cavity  Peritoneal Cavity Function: Permit movement of intestines during digestion independent of movement of the body wall  Peritoneum Thin smooth glistening serous membrane which lines the inner walls of the abdominal cavity and is reflected on to viscera (organs) to a varying degree Contains thin layer of peritoneal fluid Consists of 2 layers: – Parietal: Serous membrane layer that lines the body wall – Visceral: Serous membrane layer that covers the surface of the internal organs (viscera) Folds of peritoneum are called: 1. Omentum 2. Mesentery 3. Ligaments Organs are either intraperitoneal or retroperitoneal Fully covered by partially covered by peritoneum peritoneum Intraperitoneal versus retroperitoneal Intraperitoneal: – Visceral peritoneum covers the organ both anteriorly and posteriorly e.g. stomach & spleen Retroperitoneal: – Only covered in parietal peritoneum on anterior surface of organ – Pneumonic: SAD PUCKER – S Suprarenal(adrenal) glands – A Aorta (&IVC) – D Duodenum (except the proximal 2cm, the duodenal cap) – P Pancreas (except the tail) – U Ureters – C Colon (ascending and descending parts) – K Kidneys – E (O)esophagus – R Rectum  Peritoneal Cavity Lesser sac is a diverticulum or recess of peritoneum behind the stomach which extends up and down to a varying degree Greater sac = most of the space in the Epiploic foramen = peritoneal cavity Entrance to Lesser sac = Foramen of Begins superiorly at Winslow Passage between diaphragm and the two sacs continues inferiorly into the pelvic cavity  Parts of the Peritoneal Cavity Supracolic area - superior to transverse colon Infracolic area - inferior to transverse colon Paracolic area (gutter) - lateral to ascending & descending colons  Spaces/Recesses of the Peritoneal CavityBeneath the diaphragm Rt. subphrenic May be sites of space collection of inflammatory fluid during infection Morison’s pouch = in patient in supine Hepatorenal position, most (Morison’s) Beneath the liver pouch dependent space in Between liver and right kidney the peritoneal cavity – preferential site for metastases and abscesses Right subhepatic space includes the Morison’s space?  Peritoneal Cavity: Male versus female Excess fluid (e.g. blood, pus, infected fluid) likely to collect in the most inferior portion of the peritoneal cavity when patient stands Male: rectovesical pouch located between rectum and bladder Female: Rectouterine pouch (of Douglas) between the rectum and the posterior wall of the uterus Vesicouterine pouch between the anterior surface of uterus and bladder  Arterial Blood Supply to Abdomen + Peritoneal Cavity Foregut Bld Supp: Coeliac trunk (T12) Midgut From 2nd part of duodenum to 2/3rd across transverse colon Bld Supp: Superior Mesenteric Artery (L1) Hindgut From 2/3rd across transverse colon to anus Bld Supp: Inferior Mesenteric Artery (L3)  Venous & Lymphatic Drainage Venous Inferior Mesenteric Vein to Splenic Vein Splenic + Superior Mesenteric Vein = Portal Vein Portal vein to liver (then to inferior vena cava) Lymphatic With arteries to pre-aortic lymph nodes ▪Coeliac ▪Superior Mesenteric ▪Inferior Mesenteric Nerve Supply of the Peritoneum ▪ Parietal layer on body wall Somatic nerves – Sensitive to well-localised pain the same as skin - pain, temp, laceration & pressure ▪ Visceral layer on organs Autonomic nerves (sympathetic & parasympathetic) Stretch & tearing sensitive Referred pain & poorly localised sensations of discomfort Pain from visceral peritoneum is referred to dermatomes supplied by the same sensory ganglia and spinal cord segments as the nerve fibres innervating the viscera Visceral Afferents/Pain  Gastrointestinal Tract Regions Foregut Midgut Hindgut Oesophagus (distal end) Duodenum (distal half) Transverse colon (distal Stomach Jejunum third) Duodenum (proximal Ileum Splenic flexure half) Cecum Descending colon Liver Appendix Sigmoid colon Gallbladder Ascending colon Rectum Pancreas Hepatic flexure of colon Spleen Transverse colon (proximal two-thirds) Coeliac Trunk Superior Mesenteric Art Inferior Mesenteric Art Splenic Vein Superior Mesenteric Vein Inferior Mesenteric Vein T5 – T10 T9 – T11 L1 & L2  Peritoneum Thin smooth glistening serous membrane which lines the inner walls of the abdominal cavity and is reflected on to viscera (organs) to a varying degree Contains thin layer of peritoneal fluid Consists of 2 layers: – Parietal: Serous membrane layer that lines the body wall – Visceral: Serous membrane layer that covers the surface of the internal organs (viscera) Folds of peritoneum are called: 1. Omentum 2. Mesentery 3. Ligaments Abdomen – the first view  Greater Omentum Known as “Abdominal Policeman” Lower, right & left margins free For example, in inflamed appendix, omentum adheres to appendix thus localising infection to a small area of the peritoneal cavity preventing a serious diffuse peritonitis Great Omentum – Blood Supply Below the Greater Omentum  Recall: Peritoneal Cavity Lesser sac is a diverticulum or recess of peritoneum behind the stomach which extends up and down to a varying degree Epiploic foramen = Greater sac = most Entrance to Lesser of the space in the sac = Foramen of peritoneal cavity Winslow Begins superiorly at diaphragm and continues inferiorly into the pelvic cavity  Lesser Omentum Extends from lesser curvature of stomach & 1st part of duodenum to inferior surface of liver Divided into: – Medially between stomach & liver – Laterally between duodenum & liver Free edge: – Usually common bile duct to the right, proper hepatic artery to the left & portal vein behind and between – but variations are common Epiploic foramen/Aditus to Lesser sac/Foramen of Winslow = Opening between greater and lesser sacs Lesser Omentum  Rotation of Stomach L L L Dorsal border grows faster than the ventral border resulting in the lesser and greater curvatures Two rotations: Initially developing in the midline, it rotates 90 degrees clockwise first, then rotates along the anteroposterior axis slightly clockwise  Development of Stomach & Mesenteries Ventral mesentery Dorsal mesentery Foregut gives rise to distal end of oesophagus, stomach & proximal part of duodenum Suspended from body wall by both ventral & dorsal mesenteries  Development of Stomach & Mesenteries Epiploic foramen Developing stomach rotates clockwise & dorsal mesentery expands & moves to left Part of mesentery secondarily fuses with left side of body wall Epiploic (omental) foramen of Winslow = restricted opening  Development of Stomach & Mesenteries Omental bursa (lesser sac) Epiploic foramen Omental bursa (lesser sac) is enclosed by the expanded dorsal mesentery & lies posterior to the stomach Access to the rest of peritoneal cavity (greater sac) via omental foramen  Development of Stomach & Mesenteries Lesser omentum Greater omentum Dorsal mesentery greatly expands inferiorly to form the apron-like greater omentum Greater omentum is suspended from greater curvature of stomach & lies over other viscera in abdominal cavity  Peritoneum Thin smooth glistening serous membrane which lines the inner walls of the abdominal cavity and is reflected on to viscera (organs) to a varying degree Contains thin layer of peritoneal fluid Consists of 2 layers: – Parietal: Serous membrane layer that lines the body wall – Visceral: Serous membrane layer that covers the surface of the internal organs (viscera) Folds of peritoneum are called: 1. Omentum 2. Mesentery 3. Ligaments  Mesenteries Peritoneal folds that attach viscera to posterior abdominal wall Allow some movement Provides conduit for vessels, nerves & lymphatics to reach viscera 1. The mesentery (small intestine) 2. Transverse mesocolon Derivatives (transverse colon) of dorsal 3. Sigmoid mesocolon (sigmoid mesentery colon)  Peritoneum Thin smooth glistening serous membrane which lines the inner walls of the abdominal cavity and is reflected on to viscera (organs) to a varying degree Contains thin layer of peritoneal fluid Consists of 2 layers: – Parietal: Serous membrane layer that lines the body wall – Visceral: Serous membrane layer that covers the surface of the internal organs (viscera) Folds of peritoneum are called: 1. Omentum 2. Mesentery 3. Ligaments  Peritoneal Ligaments 2 layers of peritoneum that connect 2 organs to each other / an organ to the body wall & may form part of an omentum Splenorenal (lienorenal) ligament: left kidney to spleen Gastrophrenic ligament: stomach to diaphragm Gastrosplenic ligament: stomach to spleen Falciform ligament is the liver's reflection of peritoneum with anterior wall and was the primitive ventral mesentery. Round ligament (Ligamentum Teres Hepatis) hangs down from the falciform ligament, on the anterior side (remnant of umbilical vein).  Clinical *Peritonitis: inflammation of peritoneum *Ascites: abnormal accumulation of fluid within the peritoneal cavity Between the right costal margin and the midclavicular line Murphy’s Trans point pyloric plane Mc Burney’s X point 1/3 distance from ASIS to umbilicus Thanks and Questions?