Anterior Abdominal Wall & Peritoneum Lecture 4 PDF

THE ABDOMEN Part of the trunk between the thorax and the pelvis Contains - organs of the alimentary system, urogenital system It is bounded: – Superiorly by the diaphragm – Posteriorly by the vertebral column – Anterolaterally by the transverse and oblique muscles of the abdominal walls as well as t...

THE ABDOMEN Part of the trunk between the thorax and the pelvis Contains - organs of the alimentary system, urogenital system It is bounded: – Superiorly by the diaphragm – Posteriorly by the vertebral column – Anterolaterally by the transverse and oblique muscles of the abdominal walls as well as the rectus abdominis muscle Continuous inferiorly with the pelvis Cavity of the abdominal region abdominal cavity Abdominal walls Abdominal cavity has following boundaries – anterior abdominal wall – right and left lateral abdominal walls (also called the flanks or the loins) – posterior abdominal wall Anatomical Regions of the Abdomen Abdominal cavity is divided into 9 regions – For description of location of organs within the abdominal cavity – For description of location of pain, swellings, tumors and incisions on the abdominal wall and within the abdominal cavity The reference landmarks used in the demarcation of the abdomen into 9 regions are Horizontal (Transverse) Planes: Subcostal Plane – L3 vertebra/inferior border of 10th Costal cartilage Transtubercular Plane – L5 vertebra (connecting iliac tubercles) The Vertical (Sagittal) Planes: Right and left midclavicular or midinguinal planes Regions of abdominal cavity 1. Right hypochondriac region 2. Left hypochondriac region 3. Epigastric region 4. Right lateral (Lumbar) region 5. Left lateral (lumbar) region 6. Umbilical region 7. Right Inguinal region 8. Left Inguinal region 9. Hypogastric (Pubic) region Other important Planes The transpyloric plane – L1: Horizontal plane between the upper ends of sternum and the upper border of the pubic symphysis The transpyloric plane is a useful landmark because many structures are located along this plane – pylorus of stomach, fundus of the gall bladder, neck of the pancreas, origins of superior mesenteric artery and hepatic vein, duodenojejunal junction, hila of the kidneys, tip of ninth costal cartilage The transumbilical plane – L3/L4 This plane along with median plane divides the abdomen into 4 quadrants - Right & Left Upper quadrants, Right & Left Lower quadrants. Interspinous plane – connecting anterior superior iliac spines The plane of the highest point of the iliac crest Anterolateral abdominal wall Anterolateral abdominal wall contains following layers – Skin – Superficial fascia – Muscles of anterior abdominal wall – Transversalis fascia – Extraperitoneal connective tissue – Peritoneum (parietal layer) Skin: Supplied by lower 6 thoracic nerves and 1st lumbar nerve Presents a scar called Umbilicus Umbilicus is the area where the umbilical cord was attached It lies at the level of junction between 3rd and 4th lumbar vertebra Superficial fascia: below the umbilicus has 2 layers Superficial fatty layer (Camper’s fascia) Deep membranous layer (Scarpa’s fascia) Muscles of anterior abdominal wall: 5 muscles on each side – – – – – External oblique Internal oblique Transversus abdominis Rectus abdominis Pyramidalis Linea alba It is a midline raphe (suture) formed when aponeuroses of 3 flat muscles interweave with their fellows of the opposite side This extends from the xiphoid process to the pubic symphysis Anterolateral abdominal wall - muscles Superficial fascia Skin External oblique Internal oblique Rectus abdominis Aponeurosis Inguinal ligament Superficial inguinal ring Pyramidalis External oblique Origin: Lower 8 ribs Insertion: Linea alba, pubic symphysis, pubic tubercle, iliac crest, Nerve supply: Lower 6 thoracic nerves Lower part of the aponeurosis forms inguinal ligament which extends between anterior superior iliac spine and pubic tubercle Lower part of aponeurosis near midline presents an opening – superficial inguinal ring External oblique Inguinal ligament Superficial inguinal ring Aponeurosis Internal oblique Origin: Lateral part of inguinal ligament, iliac crest, thoracolumbar fascia Insertion: Lower 3 ribs, linea alba, pecten pubis (conjoint tendon) Nerve supply: Lower 6 thoracic nerves and 1st lumbar nerve Internal oblique Origin: Lateral part of inguinal ligament, thoracolumbar fascia and lower 6 ribs Insertion: Linea alba, pubic crest, pecten pubis (conjoint tendon) Nerve supply: Lower 6 thoracic nerves and 1st lumbar nerve Transversus abdominis Transversus abdominis Conjoint tendon Rectus abdominis Origin: Pubic crest and pubic symphysis Insertion: Xiphoid process and 5th, 6th and 7th costal cartilages Nerve supply: Lower 6 thoracic nerves Tendinous intersections Actions of main muscles of anterior abdominal wall Support for abdominal organs Expulsive acts like micturition, defecation, parturition, vomiting by compressing abdominal organs Forceful expiratory acts – by depressing and compressing the lower part of thorax (external oblique) Movements of trunk – – Flexion of trunk (rectus abdominis) – Lateral flexion of trunk (oblique muscles) – Rotation of trunk (external oblique and internal oblique of different sides) Pyramidalis Small triangular muscle situated in front of lower part of rectus abdominis Origin: Body of pubis Insertion: Linea alba Nerve supply: Subcostal nerve Actions: Tenses the linea alba Pyramidalis Rectus sheath Superior epigastric artery and vein Strong, incomplete fibrous Costal margin compartment of the rectus abdominis and pyramidalis muscles Has anterior and posterior walls Anterior wall is complete Posterior wall incomplete, absent above the costal margin and below the arcuate line Formation of rectus sheath: Upper part (above costal margin): Anterior wall – external oblique aponeurosis Arcuate Posterior wall is absent, muscle line Inferior epigastric rests on costal cartilages artery and vein Rectus sheath Middle part (between costal margin and arucate line): Anterior wall – external oblique aponeurosis and anterior layer internal oblique aponeurois Posterior wall – transversus abdominis aponeurosis and posterior layer internal oblique aponeurosis Lower part (below arcuate line): Anterior wall – aponeurosis of all 3 muscles Posterior wall is absent, muscle rests on transversalis fascia Contents: Rectus abdominis, pyramidalis Superior and inferior epigastric arteries and veins Lower 5 intercostal nerves, subcostal nerve Nerves and blood vessels of anterolateral abdominal wall Nerves: Lower 6 thoracic nerves – Lower 5 intercostal nerves – Subcostal nerve First lumbar nerve (iliohypogastric nerve and ilioinguinal nerve) Blood vessels: Lower 5 posterior intercostal arteries and veins Subcostal artery and vein Superior epigastric artery and vein Inferior epigastric artery and vein Lymphatic drainage: Lymph vessels above the umbilicus terminate at axillary lymph nodes Lymph vessels below the umbilicus terminate at superficial inguinal lymph nodes Inguinal canal Oblique passage situated at the lower part of anterior abdominal wall, just above the medial part of inguinal ligament About 4 cm long, extends from deep inguinal ring to the superficial inguinal ring Deep inguinal ring: Located in the fascia transversalis about ½ inch above the midinguinal point, just lateral inferior epigastric artery Superficial inguinal ring: Located in the aponeurosis of external oblique muscle, just above the pubic crest Inguinal canal Aponeurosis of external oblique muscle Peritoneum Fascia transversalis External oblique Internal oblique Inguinal ligament Superficial Spermatic inguinal ring cord Transversus abdominis Boundaries of inguinal canal: Floor: Inguinal ligament and lacunar ligament Roof: Arched fibres of transversus abdominis and internal oblique muscle Anterior wall: Skin, superficial fascia, external oblique aponeurosis Internal oblique in the lateral part Posterior wall: Transversalis fascia, extraperitoneal connective tissue, peritoneum Conjoint tendon in the medial part (formed by internal oblique and transversus abdominis muscles) Contents of inguinal canal: Ilioinguinal nerve Spermatic cord (in males) and round ligament of uterus (in females) Inguinal hernia: Abnormal protrusion of contents of abdomen (eg intestine) into the inguinal canal Direct inguinal hernia: Contents enter inguinal canal directly by piercing the posterior wall of inguinal canal – Lateral direct hernia – Medial direct hernia Indirect inguinal hernia: Contents enter the inguinal canal through deep inguinal ring Peritoneum Peritoneum Glistening and slippery transparent serous membrane Lines the wall of abdominal and pelvic cavities and encloses the organs Made up of outer layer of connective tissue and inner layer of mesothelium (single layer of squamous cells) Contains peritoneal cavity which is invaginated by number of structures in the abdomen Layers of peritoneum: has 2 layers which are continuous with each other Parietal peritoneum and visceral peritoneum Parietal peritoneum Lines the inner surface of abdominal and pelvic walls Loosely attached to the walls by extraperitoneal connective tissue Separated from visceral peritoneum by peritoneal cavity Develops from somatopleuric mesoderm Blood supply and nerve supply is same as that of wall which it lines Supplied by somatic nerves – sensitive to pressure, pain, heat and cold, and laceration Visceral peritoneum Lines the outer surface of organs Firmly adherent to the organs Develops from splanchnopleuric mesoderm Blood supply and nerve supply are same as those of underlying organs Supplied by autonomic nerves – insensitive to touch, heat and cold, and laceration; it is stimulated primarily by stretching and chemical irritation Forms folds of peritoneum which connect the organs to the wall or organ to another organ Peritoneal cavity Is within the abdominal cavity and continues inferiorly into the pelvic cavity Potential space of capillary thinness between the parietal and visceral layers of peritoneum Contains peritoneal fluid - produced by the mesothelial cells lining the peritoneum Fluid allows free movements of one organ over the other and allowing the movements of digestion Peritoneal cavity is completely closed in males. In females it communicates with the exterior of the body through the uterine tubes, uterine cavity, and vagina (forms a potential pathway of infection from the exterior) Peritoneal folds Folds of peritoneum connect organ to the wall Folds connect one organ to the other organ Peritoneal folds suspend the organs and allow the organ to move within the abdomen Peritoneal folds contain fat, blood vessels, nerves and lymph vessels Omentum Is a double-layered extension or fold of peritoneum that passes from the stomach (and proximal part of the duodenum) to adjacent organs in the abdominal cavity Lesser omentum: Double-layered peritoneal fold that connects the lesser curvature of the stomach and the proximal part of the duodenum to the liver Greater omentum: Four-layered peritoneal fold that hangs down like an apron from the greater curvature of the stomach and the proximal part of the duodenum to the posterior abdominal wall Liver Diphragm Lesser omentum Duodenum Greater omentum GastroSplenic ligament Spleen Mesentery Fold suspending small and large intestine The mesentery – fold suspending jejunum and ileum Transverse mesocolon – fold which suspends the transverse colon Sigmoid mesocolon – fold which suspends sigmoid colon Mesoappendix – fold which suspends the appendix Peritoneal ligaments A peritoneal ligament consists of a double layer of peritoneum that connects an organ with another organ or to the abdominal wall. Grastosplenic ligament – connecting stomach and spleen Gastrophrenic ligament – connecting the stomach and diaphragm Leinorenal ligament – connecting the spleen and left kidney Phrenicocolic ligament – connecting left flexure of colon to the diaphragm Left and right triangular ligaments - connect the liver and diaphragm Flaciform ligament - connects the liver to the anterior abdominal wall and diaphragm Superior and inferior layers of coronary ligaments - connect the liver to the diaphragm Lesser omentum Fold of peritoneum connecting the liver to stomach and proximal part of duodenum Forms the anterior boundary of lesser sac Attachments: Superior: porta hepatis and fissure for ligamentum venosum of liver Inferior: lesser curvature of stomach and first (superior) part of duodenum Parts: Hepatogastric ligament and hepatoduodenal ligament Right free margin: Forms the anterior boundary of Epiploic foramen Contents: At the right free margin Bile duct, hepatic artery, portal vein Hepatic plexus of nerves, lymphatics of liver Near lesser curvature of stomach Right and left gastric vessels Epiploic foramen Bile duct Hepatic artery Greater omentum Fold of peritoneum connecting stomach and duodenum to the pancreas (posterior wall of abdomen) Attachments: – Greater curvature of stomach and first (superior) part of duodenum – Posterior abdominal wall Has anterior 2 layers and posterior 2 layers Lesser sac is situated between the anterior and posterior layers Anterior 2 layers descend from the greater curvature of stomach and first part of duodenum Descend in the abdomen for a variable distance and take a turn and continue as posterior 2 layers Posterior 2 layers ascend upwards Run in front of transverse colon and transverse mesocolon and blend with them Attached to posterior abdominal wall (pancreas) Contents of greater omentum: Fat, right and left gastroepiploic vessels, macrophages (milky spots) Function: Storehouse of fat Prevents the spread of infection Hepatic artery Right gastroepiploic artery Left gastric artery Splenic artery Left gastroepiploic artery Greater omentum The Mesentery Transverse Peritoneal fold which suspends the coils of colon jejunum and ileum of small intestine from posterior abdominal wall Has 2 borders – attached and free borders Attached border (root of the mesentery): 15 cm long, attached to the posterior abdominal wall Free (intestinal) border: 6 meters long, encloses the ileum and jejunum Contents: Jejunal and ileal arteries and vein Lymph nodes, lymphatics and nerves of jejunum and ileum Connective tissue and fat Vermiform Transverse mesocolon Mesentery appendix Colis of jejunum Jejunal and and ileum ileal vessels Mesoappendix: Fold of peritoneum which suspends the vermiform appendix from the mesentery Contains arteries, veins, nerves and lymphatics of appendix Attached border (root) Free border Vermiform appendix with mesoappendix Mesentery Coils of jejunum and ileum Transverse colon Transverse mesocolon Sigmoid colon Sigmoid mesocolon Transverse mesocolon: Fold of peritoneum which suspends the transverse colon from the upper part of posterior abdominal wall (pancreas) Contains middle colic artery and vein, nerves, lymph nodes and lymphatics of transverse colon Sigmoid mesocolon: Triangular fold of peritoneum which suspends the sigmoid colon from the pelvic wall Contains sigmoid arteries and veins, nerves, lymph nodes, lymphatics of sigmoid colon Gastrosplenic ligament: Connects the stomach and spleen Contains short gastric vessels and left gastroepiploic vessels Lienorenal (splenicorenal) ligament: Connects spleen and left kidney Contains splenic vessels and tail of pancreas Falciform ligament: Connects the liver to the diaphragm and anterior abdominal wall Its free margin contains ligamentum teres and paraumbilical veins Right triangular ligament Superior layer of Diaphragm Left triangular Fissure for coronary ligament ligament ligamentum venosum Falciform ligament Liver Ligamentum teres Inferior layer of Porta hepatis coronary ligament Right triangular ligament Parts of peritoneal cavity: Folds of peritoneum divide the peritoneal cavity into 2 cavities – greater sac and lesser sac Greater and lesser sacs connected by epiploic foramen Lesser sac Part of peritoneal cavity situated behind the lesser omentum and stomach Lower part lies within the greater omentum Communicates with the greater sac through the epiploic foramen It is located behind the liver, lesser omentum, stomach and anterior 2 layers of greater omentum Following are located behind lesser sac - diaphragm, pancreas, transverse colon, transverse mesocolon, left kidney, left suprarenal gland, splenic artery, splenic flexure of colon Epiploic foramen Foramen connecting lesser and greater sacs Situated behind the right free margin of lesser omentum Situated on the right wall of lesser sac Boundaries: Anterior: Right free margin of lesser omentum contianing portal vein, hepatic artery and bile duct Posterior: Inferior vena cava Superior: Caudate process of liver Inferior: First (superior) part of duodenum Clinical significance: Internal hernia Supra and infracolic compartments: Transverse colon and transverse mesocolon divides the peritoneal cavity into supracolic and infacolic compartments Supracolic compartment: Is divided into many subdivisions – right and left subphrenic spaces right and left subhepatic spaces Left subhepatic space is also known as lesser sac Right subhepatic space is also known as hepatorenal pouch Hepatorenal (Morison’s) pouch: Most dependent part of peritoneal cavity in supine position It is located behind the liver and in front of right kidney Stomach Gastrosplenic ligament Gall bladder Spleen Liver (right lobe) Pancreas Hepatorenal pouch Right flexure of colon Right kidney Duodenum (2nd part) Greater omentum Rectouterine pouch (pouch of Douglas): Most dependent part of peritoneal cavity in the females in upright Uterovesical position pouch Boundaries: Anterior – uterus, upper part of vagina Posterior – rectum Urinary bladder Contents: Coils of ileum, sigmoid Uterovesical pouch colon Uterovesical pouch: Situated between the uterus and urinary bladder Uterus Rectouterine pouch Rectum Vagina Recto uterine pouch Rectovesical pouch: Lowest part of peritoneal cavity in the males in upright position Boundaries: Anterior – urinary bladder, seminal vesicle Posterior - rectum Rectovesical pouch Urinary bladder Rectum Rectum Seminal vesicle