ABDOMINAL CAVITY the second lecture Abdominal cavity Esophagus Peritoneum Peritoneal cavity Stomach Abdominal aorta Celiac trunk Celiac plexus Esophagus Fibromuscular tube Extends from the pharynx to the stomach Approximately 25 cm long Average diameter of 2 cm Usually flattened anteroposteriorly Descends through the neck, superior and posterior mediastinum, abdominal cavity (short part) Conveys food from the pharynx to the stomach Food passes rapidly because of the peristaltic action of its musculature Esophagus Initially inclines to the left but is moved by the arch of the aorta to the median plane opposite the root of the left lung Inferior to the arch again deviates to the left Passes through the esophageal hiatus in diaphragm at the level of T10 vertebra Esophagus – cervical part Extends from the level of inferior border of C6 and inferior border of the cricoid cartilage. Esophagus -thoracic part (superior mediastinum) Enters the superior mediastinum between the trachea and vertebral column Lies anterior to the bodies of the vertebrae T1 through T4 Esophagus- thoracic part (superior mediastinum) Adjacent to the posterior surface (membranous wall) of the trachea Esophagus - thoracic part (superior mediastinum) The thoracic duct usually lies on the left side of the esophagus, deep (medial) to the arch of the aorta Esophagus - thoracic part (inferior mediastinum) Passes posterior to the pericardium and the left atrium Esophagus - abdominal part Short, trumpet-shaped Approximately 1.25cm long Extends from the diaphragm to the cardiac orifice of the stomach to the left of the midline at the level of the 7th left costal cartilage and T11 vertebra The right border- continuous with the lesser curvature of the stomach The left border- is separated from the fundus of the stomach by the cardiac notch Esophageal hiatus Esophagus- constrictions Normally has four constrictions where adjacent structures produce impressions: The upper esophageal sphincter- at the beginning, approximately 15 cm from the incisor teeth and caused by the cricopharyngeus muscle Where is crosed by the arch of the aorta, 22.5cm from the incisor teeth Where is crossed by the left main bronchus, 27.5cm from the incisor teeth The lower esophageal sphincter- where passes through the diaphragm, approximately 40 cm from the incisor teeth Esophagus- constrictions (impressions) May be observed as narrowings of the lumen in oblique chest radiographs that are taken as barium is swallowed At these sites- the slower passage of substances The impressions indicate: -where swallowed foreign objects are most likely to lodge -where a stricture may develop following the accidental drinking of a caustic liquid such as lye Esophagus- musculature Layers of muscle: internal circular external longitudinal - in the superior third consists of skeletal muscles (voluntary, striated) - in the middle third is made up of smooth and skeletal muscles (a mixture of striated and smooth) - in the inferior third is composed of smooth muscle (involuntary) The phrenoesophageal ligament (membrane) An extension of inferior diaphragmatic fascia Attaches the esophagus to the margins of the esophageal hiatus in the diaphragm Stabilizes and maintains the esophagogastric junction in intrabdominal position Permits independent movement of the diaphragm and esophagus during respiration and swallowing Esophagogastric junction Lies to the left of T11 vertebra on the horizontal plane that passes through the tip of the xiphoid process The diaphragmatic musculature forms the esophageal hiatus- a physiological esophageal sphincter that contracts and relaxes Surgeons and endoscopists designate as the Z-line- a jagged line where the mucosa abruptly changes from esophageal to the gastric Physiological esophageal sphincter Prevents reflux of gastric contents into esophagus The lumen of the esophagus when one is not eating is normally collapsed above this sphincter Esophagus- the arterial supply Esophageal branches (from the thoracic aorta) Left gastric artery (from celiac trunk) Left inferior phrenic artery (from the abdominal aorta) Esophagus- the venous drainage To the portal venous system through the left gastric vein To the systemic venous system through esophageal veins entering the azygos vein Esophagus- the venous drainage Esophageal varices Esophageal varices, hiatus hernia, stricture and esophagitis Esophagus- the lymphatic drainage Into the posterior mediastinal lymph nodes Into the left gastric nodes (efferent lymphatic vessels from these nodes drain mainly to the celiac nodes) Esophagus- the innervation The vagal trunks The thoracic sympathetic trunks The splanchnic nerves (the greater and lesser) The esophageal nerve plexus around the left gastric and inferior phrenic arteries Peritoneum A continuous, glistening, transparent serous membrane Peritoneum Lines the abdominopelvic cavity and invests the viscera Two continuous layers: - parietal peritoneum - visceral peritoneum Both layers of peritoneum consist of mesothelium (a layer of simple squamous epithelial cells) Peritoneal cavity Within the abdominal cavity which is continuous with the pelvic cavity Potential space of capillary thinness between the parietal and visceral layers of peritoneum Contains peritoneal fluid which lubricates the peritoneal surfaces, enabling the organs to move each other without friction and allowing the movements of digestion Peritoneal cavity Completely closed in males A communication pathway in females to the exterior of the body through the uterine tubes, uterine cavity and vagina (potenthial pathway of infection from exterior) Peritoneal fluid Contains leukocytes and antibodies that resist infection Absorbed by lymphatic vessels on the inferior surface of diaphragm Embryology of the peritoneal cavity Early the embryonic body cavity is lined with mesoderm (the primordium of the peritoneum) Later, the primordial abdominal cavity is lined with parietal peritoneum derived from mesoderm, which forms a closed sac The peritoneal cavity- the lumen of the peritoneal sac The organs invaginate to varying degrees into the peritoneal sac, acquiring a peritoneal covering- the visceral peritoneum Peritoneum – the relationship of organs to the peritoneum Intraperitoneal organs-almost completely covered with visceral peritoneum (invaginate into the closed sac) Extraperitoneal (retroperitoneal) organs- outside the peritoneal cavity- external or posterior to the parietal peritoneum - primarily retroperitoneal - secondary retroperitoneal Peritoneum – the relationship of organs to the peritoneum Primarily extraperitoneal- do not have a peritoneal covering, already retroperitoneal when formed, embedded primarily in the connective tissue of the extraperitoneal space Secondarily extraperitoneal- become extraperitoneal during the course of embryonic development, attached secondarily to the wall of the peritoneal cavity by peritoneal fusion Relationships of the organs to the peritoneum Intraperitoneal organs: Secondary retroperitoneal organs: Stomach Duodenum (without ampulla) Ampulla of duodenum Ascending and descending colon Jejunum Pancreas Ileum Cecum with appendix Primarily retroperitoneal organs: Transverse colon Kidneys Sigmoid colon Ureters Liver Suprarenal glands Spleen Urinary bladder (subperitoneal) Ovaries Prostate (subperitoneal) Uterine tubes Vagina (subperitoneal) Uterus The peritoneal ligaments of the liver and the stomach Consist of a double layer of peritoneum that connects an organ with another organ or to the abdominal wall The mesentery A double layer of peritoneum A result of the invagination of peritoneum by an organ Constitutes a continuity of the visceral and parietal peritoneum that provides a means for neurovascular communication between the organ and the body wall Connects the organ to the posterior abdominal wall Has a core of connective tissue containing blood and lymphatic vessels, nerves, lymph nodes and fat Mesocolon The mesentery of the large intestine The omentum Double-layered extension or fold of peritoneum Passes from the stomach and proximal part of the duodenum to adjacent organs in the abdominal cavity or to the abdominal wall Divides into: - the lesser omentum - the greater omentum The lesser omentum Connects the lesser curvature of the stomach and the proximal part of the duodenum to the liver The hepatogastric ligament and hepatoduodenal ligament are continuous parts The greater omentum Prominent peritoneal fold Hangs down like an apron from the greater curvature of the stomach and the proximal part of the duodenum Folds back and attaches to the anterior surface of the transverse colon and its mesocolon The greater omentum Prevents the visceral peritoneum from adhering to the parietal peritoneum lining the anterolateral abdominal wall „Abdominal policeman” wraps around an inflamated organ walling it off and thereby protecting other viscera from this organ Cushions the abdominal organs against injury Forms insulation against loss body heat Peritoneal fold and peritoneal recess Peritoneal fold- a reflection of peritoneum that is raised from the body wall by underlying blood vessels, ducts and obliterated fetal vessels Peritoneal recess (fossa)- a pouch of peritoneum that is formed by a peritoneal fold The transverse mesocolon Mesentery of the transverse colon Divides the abdominal cavity into: - supracolic compartment - infracolic compartment The infracolic compartment Lies posterior to the greater omentum Divides into right and left infracolic spaces by the mesentery of the small intestine The paracolic