Abdominal Esophagus & Stomach Anatomy

• These notes cover the abdominal part of the oesophagus and stomach

Oesophagus

• Runs from the pharynx to the stomach, specifically from C6 to T11
• Divided into three parts: cervical, thoracic and abdominal
• The abdominal part is the shortest section

Oesophageal Constrictions

• Features four constrictions
• Beginning
• Where it is crossed by the arch of the aorta
• Where it is crossed by the left main bronchus
• Where it passes from the diaphragm

Abdominal Oesophagus

• Begins at the T10 vertebra
• Is 1.25 cm long
• Covered by the peritoneum on its front and left side
• It has no peritoneum on its posterior side, where the left crus of the diaphragm is located

Oesophageal Ligaments

• Gastrophrenic ligament (peritoneum)
• Phrenico-oesophageal ligament (structure: not peritoneum)
• These structures, located between the right crus of the diaphragm and the esophagus, prevent upward movement of the esophagus during swallowing and respiration

Vagus Nerve

• In the thorax and abdomen, the left vagus nerve courses on its anterior surface
• The right vagus nerve courses on its posterior surface

Abdominal Oesophagus Structure

• Adventitia: outermost layer made of connective tissue
• Muscular layer: contains an outer longitudinal layer and an inner circular layer. Made up of the following: -Skeletal muscle fibres are limited to the upper 1/3 -Middle 1/3 is made up both types -Lower 1/3 contains smooth muscle fibres
• Submucous layer: contains vessels, nerves, and mucous glands
• Mucous layer: has longitudinal folds

Oesophago-Gastric Junction

• Circular muscle fibers in both the diaphragm and oesophagus are near the junction
• The right crus encircles the oesophagus
• Obliquity of the junction and mucosal folds act as a valvular mechanism
• Forms a physiological sphincter that prevents reflux

Arterial Supply

• Supplied by the oesophageal branches of the left gastric artery and the left inferior phrenic artery

Venous Drainage

• The left gastric vein drains into the portal venous system
• Oesophageal veins drain into the axygos vein which then flows into the systemic venous system
• Creates a portacaval anastomosis

Lymphatic Drainage

• Lymph vessels drain into the left gastric lymph nodes, which then drain into the celiac lymph nodes

Nerve Supply

• Parasympathetic innervation is from the vagus nerve (right and left)
• The left vagus nerve is anterior to the oesophagus
• Sympathetic innervation is from the thoracic (greater splanchnic nerve)
• Plexuses surround the arteries
• The vagus and sympathetic fibres form two plexuses: -Myenteric (auerbach plexus): located between two layers of muscular layer -Meissner: Submucous plexus

Stomach

• Located in the epigastric, umbilical and left hypocondriac regions
• Shaped like the letter "J"
• Capacity: 30 ml in newborns; 1500 ml in adults

Important Features of the Stomach

• Cardiac orifice
• Pyloric orifice
• Lesser curvature
• Greater curvature
• Anterosuperior surface (anterior)
• Posteroinferior surface (posterior)

Parts of the Stomach

• Cardia (entrance)
• Fundus (transverse line from cardiac notch, some air)
• Body (up to angular notch)
• Pyloric part (pyloric antrum + pyloric canal)
• Pylorus (gatekeeper)

Gastric Orifices

• Cardiac orifice: located 2.5 cm left of the junction of the sternum and seventh costal cartilage
• Pyloric orifice: In the supine position with an empty stomach, it is located 1.2 cm right of the midline in the transpyloric plane

Gastric Curvatures

• Lesser: located between the cardiac and pyloric orifices -Concave -Right border of stomach -Features the angular notch -Contains the lesser omentum-hepatogastric ligament -Contains the right and left gastric arteries and veins
• Greater: Located at the cardiac notch-pylorus at the L1 vertebra level -Contains the gastrosplenic (gastrolienal) ligament, lgastroepiploic vessels and short gastric arteries and veins -The gastrophrenic ligament spans the fundus and diaphragm

Omentum (ligaments from the greater curvature)

• 1-Gastrophrenic lig
• 2- Greater omentum
• 3-Gastrosplenic
  • L gastroepiploic vessels with short gastric arteries and veins

Stomach Location

• Fundus lies at the junction between the fifth intercostal space and the mid-clavicular line
• Pylorus is located at the first lumbar vertebra

Gastric Surfaces

• Anterosuperior
• Posteroinferior

Anterosuperior Surface

• Covered by peritoneum
• When the stomach is full, it is related to the anterior abdominal wall
• Triangle: Left costal arch, Ant margin of liver, Line between right and left 10th rib
• When stomach is empty: transverse colon

Posteroinferior Surface (=Stomach Bed)

• Covered by peritoneum, except for a triangular area on the posterior surface near the cardiac orifice that directly contacts the left diaphragmatic crus
• The omental bursa is related to this surface

Relations of the Stomach Bed

• Diaphragm
• Left suprarenal gland
• Anterior surface of the left kidney
• Splenic artery
• Anterior pancreatic surface
• Left colic flexure
• Transverse mesocolon

Gastric Wall

• Serous layer: peritoneum covering the entire surface, except the attachments of greater and lesser curvatures (greater and lesser omentum) and a small posterior area near the cardiac orifice
• Muscular layer: contains longitudinal, circular and oblique fibres
• Mucous layer: mucosa has gastric folds

Arterial Supply

• Left Gastric Artery
• Right Gastric Artery
• Right Gastroomental Artery
• Left Gastroomental Artery
• Short Gastric arteries

Venous Drainage

• Splenic vein
• Superior mesenteric vein
• Portal vein
• Prepyloric vein drains into right gastric vein, and is useful to identify the pylorus

Lymphatic Drainage

• Left gastric nodes, hepatic and pyloric nodes, right gastroepiploic and right gastric nodes, and pancreaticosplenic lymph nodes

Nerve Supply

• Sympathetic innervation is via the greater splanchnic nerve (T6-9)
• Parasympathetic innervation is via the anterior (left vagus) and posterior (right vagus) vagal trunks
• This forms the coeliac plexus which branches out to become the gastric plexus