7 The Stomach
Anatomy
▪ Anatomy of the Esophagus
Location
The esophagus is located in the posterior mediastinum. It lies medial in front of the spinal column until the tracheal bifurcation (T4), after which it moves to the right side, to make room for the heart. Lastly, it crosses the diaphragm to the left of the median line. At the level of T7-T8, the aorta squeezes in between the spinal column and the esophagus. The abdominal part is only about 2 cm long.
Topographic Relationships
Thorax
trachea
left main bronchus
mediastinal pleura
pericardium
spinal column
aorta
right lung (in the area of the esophageal hiatus)
vagus nerve, right and left
Abdomen
peritoneum in the front
liver
crus to the left of the diaphragm
left side: left triangular ligament
right side: lesser omentum
T10 and T11
Attachments/Suspensions
organ pressure
turgor
mediastinal connective tissue
phrenoesophageal ligament (ring-shaped disk in the hiatus).
The esophagus remains mobile in the lengthwise direction.
Circulation
Cervical
inferior thyroid artery
small branches from the subclavian/communal carotid/vertebral arteries, etc.
inferior thyroid vein (from the superior vena cava)
Thoracic
bronchial arteries
aorta
azygos/hemiazygos/accessory hemiazygos vein (from the superior vena cava)
Abdominal
left gastric artery
inferior phrenic artery
celiac trunk
left gastric vein (main drainage) to the portal vein
Lymph Drainage
deep cervical cord (internal jugular vein-parotid gland-clavicle)
intercostal, thoracic nodes near the spinal column
paratracheal nodes along the recurrent laryngeal nerve
tracheobronchial nodes
These nodes all drain into the right/thoracic lymphatic duct.
nodes around the celiac trunk (cisterna chili—thoracic duct)
Innervation
sympathetic nervous system from T4 to T6
further path of sympathetic innervation: pharyngeal plexus-superior cervical/stellate ganglion-greater splanchnic nerve-celiac plexus
vagus nerves accompany the esophagus into the abdomen
▪ Anatomy of the Stomach
Location
Division into:
cardia (stomach entrance)
fundus (cranial region, filled with air)
body
antrum
pylorus
greater curvature
lesser curvature
Cardia and pylorus are relatively fixed points; in between, great variability is possible depending on the state of fullness.
Topographic Relationships
diaphragm
indirect: pleura and left lung, pericardium and heart
ribs 5–8 and costal cartilage 9 on the left
liver
celiac trunk and plexus
omental bursa
left crus of the diaphragm
left adrenal gland
left kidney
pancreas
transverse colon
transverse mesocolon
left colic flexure
duodenum (horizontal and ascending part)
duodenojejunal flexure and start of the jejunum
spleen
Attachments/Suspensions
organ pressure
turgor
gastrophrenic ligament
lesser omentum
greater omentum
gastrocolic ligament
gastrolienal ligament
left phrenicocolic ligament
Circulation
Arterial
right gastric artery (from proper hepatic artery)
left gastric artery (from celiac trunk, anastomosed with the right gastric artery)
right gastro-omental artery (gastroduodenal artery)
left gastro-omental artery (splenic artery—celiac trunk)
gastroduodenal artery (common hepatic artery—celiac trunk)
Venous
Portal vein.
Lymph Drainage
paracardial lymph nodes
pancreatic lymph nodes
splenic nodes
celiac nodes—thoracic duct (main drainage)
Innervation
sympathetic nervous system from T6 to T9 via the greater and lesser splanchnic nerves
further path of sympathetic innervation runs to the celiac and superior mesenteric ganglion
vagus nerve
Organ Clock
Maximal time: 7-9a.m.
Minimal time: 7-9p.m.
Organ-Tooth Interrelationship
For basic information, see page 34.
Second premolar in the lower jaw on both sides
Second molar in the upper jaw on both sides
Movement Physiology according to Barral
Mobility
The esophagus has lengthwise mobility. During movements of the head and neck, it must be able to adjust its length.
To transport food, peristaltic waves run through the esophagus during the act of swallowing.
The stomach shows mobility in three planes: frontal, sagittal, and transverse.
Frontal Plane
During inhalation, the diaphragm guides the lateral parts of the fundus of the stomach inferomedially. The distance between the lesser and greater curvature decreases, as does the distance between the fundus and antrum. Looked at from the front, the stomach rotates in a clockwise direction.
The axis of movement is a sagittotransverse axis through the angular incisure of the lesser curvature.
Sagittal Plane
In this plane, the stomach performs a tilt with the cranial parts of the fundus in an anterior direction, accompanied by a simultaneous shift posteriorly in the antral area. The frontotransverse axis of movement runs roughly through the center of the stomach.
Transverse Plane
The stomach performs a rightward rotation along a frontosagittal axis through the inferior part of the esophagus.
Motility
The motions of motility correspond in direction and axis to those of mobility.
Physiology
Proximal and Distal Stomach
The relief structure of the stomach wall serves as a “slide” for the chyme in the direction of the pylorus. The proximal stomach acts as food storage and is marked by continuous tension in the walls.
The distal stomach has the task of mixing, homogenizing, and emulsifying the food. For this purpose, peristaltic waves run from a central pacemaker through the distal stomach. A distension in the stomach stimulates these waves; a distension in the small intestine inhibits the activity of the distal stomach (enterogastric reflex).
The pylorus does not close so tightly that fluids are unable to pass. It relaxes synchronously with each contractile wave of the distal stomach, but only far enough that small food particles can still pass while the large parts are thrown back.
Main Functions of the Stomach
grinding up solid food, emulsification of fats, predigestion of proteins
secretion of gastric juice
Gastric Juice
Mucus
Mucus is secreted by the epithelial cells on the surface of the stomach, the side cells of the fundic glands, and the cardiac and pyloric glands.
Bicarbonate
Bicarbonate is secreted by the epithelial cells in the stomach mucosa.
Both components of gastric juice serve to protect the stomach walls from hydrochloric acid (HCl). An H+ gradient exists across the mucosa, from strongly acid on the lumen side to slightly alkaline on the epithelium side (effect of bicarbonate).
Pepsinogen
Pepsinogen is secreted by the chief cells of the fundic and body glands. At a pH < 3, it is activated into pepsin and cleaves proteins.
Hydrochloric Acid
Hydrochloric acid is secreted by the parietal cells in the fundic glands.
Intrinsic Factor
The intrinsic factor is necessary for the absorption of vitamin B12 in the small intestine.
Regulating the Secretion of Gastric Juice
The secretion of gastric juice has several trigger mechanisms.
Cephalic Phase
The secretion of gastric juice is stimulated via the vagus nerve by smell, taste, and glucose deficiency in the brain.
Gastric Phase
Distension of the stomach, amino acids (especially tryptophan and phenylalanine), and Ca2+ ions increase the secretion of gastric juice.
Intestinal Phase
This is stimulation by the voiding of chyme into the duodenum. The secretion of gastric juice is inhibited by a strongly acid pH balance in the stomach which inhibits the release of gastrin; this, in turn, inhibits the secretion of HCl in the parietal cells.
Hormones
Gastrin
Gastrin is secreted by the antral glands (two-thirds) and the duodenal mucosa (one-third).
Release Stimulation
presence of peptides or certain amino acids
vagal efferents
high catecholamine concentration in the plasma
Release Inhibition
The pH of gastric juice is < 3.
Functions
stimulates HCl secretion in the parietal cells
increases strength and frequency of antral peristalsis
promotes epithelial growth in the stomach and duodenum
stimulates the pancreatic acini, bile secretion, and gallbladder contraction
Cholecystokinin
Cholecystokinin (CCK) is secreted in the duodenal and jejunal epithelia.
Release Stimulation
Presence of free fatty acids, peptides, aromatic amino acids, or glucose in the duodenal lumen.
Release Inhibition
Trypsin in the intestinal lumen (protein-cleaving enzyme from the pancreas).
Functions
stimulates the acinar cells of the pancreas (neutral chloride-rich juice with proenzymes)
stimulates the secretion of alkaline pancreatic juice rich in bicarbonate
releases all pancreatic hormones
promotes pancreatic growth
stimulates the chief cells of the stomach (⇒ pepsinogen ↑)
inhibits HCl secretion
strong stimulator of gallbladder contraction, opens the sphincter of Oddi
satiety hormone
Secretin
Secretin is secreted in the duodenal and jejunal epithelium.
Release Stimulation
Acid chyme.
Functions
stimulates the secretion of alkaline pancreatic juice rich in bicarbonate
alkalizes the bile in the bile duct system
inhibits the resorption of water and salt in the gallbladder
slows down the emptying of the stomach by inhibiting the stomach muscles
antitrophic effect on the gastric mucosa
Pathologies
▪ Symptoms that Require Medical Clarification
Tarry stools
Signs of peritonitis
Upper abdominal pain that worsens or improves on food intake
Palpable lymph node at the medial end of the left clavicle (Virchow node)
Hiatus Hernia
Definition
Prolapse of parts of the stomach or of the entire stomach (possibly even of other organs) through the esophageal hiatus into the thorax.
Forms
Sliding Hernia
Movement of the cardia and fundus into the rear mediastinum, with the pointed angle of His being lifted.
Frequently asymptomatic. About 25% of patients develop reflux symptoms; reflux esophagitis is possible (5% of cases).
Paraesophageal Hernia or Rolling Hernia
Protrusion of parts of the fundus into the thorax (past the esophagus and the cardia, which is fixed in its normal location), with a pointed angle of His.
The sphincter continues functioning and reflux is unlikely to occur. Cardinal symptoms are pain in the epigastrium and iron deficiency anemia.
Hybrid forms between the two are possible.
Functional Hernia according to Barral
In cases with similar symptoms, the radiological signs of a hiatus hernia are absent. Such conditions can be caused by a spasm in the gastroesophageal transition or nonphysiologic tissue pulls in the peritoneum, ligaments, or fascia.
Prerequisites for a Healthy Sphincter Function according to Barral
physiologic pressure conditions in the abdomen and thorax
causes for pathologic changes: pregnancy, cough, obstipation with impaired defecation
soft anatomic surroundings that are free from nonphysiologic tissue pulls
causes for pathologic changes: surgery or effects of inflammation
physiologic lengthwise tension in the esophagus
causes for pathologic changes: kyphotic posture or inflammation
functional diaphragm tension and position
for healthy sphincter function, the angle of His must be pointed
normotonic muscle tension at the gastroesophageal transition
Clinical. Roughly 95% of all reflux patients have a hiatus hernia; by contrast, only about 5% of patients with hiatus hernia have reflux disease.
Note
Cardinal symptoms of reflux disease include:
pain in the epigastrium
heartburn
Additional symptoms:
regurgitation
retrosternal burning
pain in the middle to lower thoracic spinal column (TSC)
The symptoms are aggravated by:
lying down
lifting heavy loads
bending down
food intake
stress
alcohol
nicotine
Acute Gastritis
Definition. Acute inflammation of the gastric mucosa with loss of the protective mucus barrier and damage to the mucosa from gastric acid.
Causes
Exogenous factors:
Bacteria (Helicobacter pylori) or toxins (staphylococci)
alcohol
medications (acetylsalicylic acid, nonsteroidal antirheumatics or NSARs, cytostatics)
Endogenous factors:
uremia
portal hypertension
stress-related ischemia (trauma, burns, shock, competitive sports)
food allergies
Clinical
epigastric pain
nausea
vomiting
lack of appetite
diarrhea
bad breath
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