Monday, May 30, 2011

Esophageal Disease

ANATOMY OF THE ESOPHAGUS\
  •  cricopharyngeus, the first region of anatomical constriction
  • Retropharyngeal danger space: possibility of infection spread ing retroesophageally into the thorax
  • Tunica Muscularis
    • Inner circular: continuous superiorly with the circumferential fibers of the inferior pharyngeal constrictor
    • Outer longitudinal: upper third is striated (voluntary muscle) like the pharynx; middle third is a combination of striated and smooth muscle; lowest third is smooth muscle
    Innervation - - - - - - Figure
    • The esophageal nerve plexus is composed of vagal afferent and efferent, sympathetic efferent, and segmental sensory components
    • Parasympathetic preganglionic fibers
      • Upper (cervical) portion from the recurrent laryngeal nerve
      • Thoracic portion from the vagus via the pulmonary plexus (peribronchial)
      • Ganglion cells located in myenteric plexuses
    • Sympathetic postganglionic fibers
      • Via nerves from cervical and thoracic chains
      • From cervical ganglia and thoracic ganglia
    • Sensory fibers (visceral afferent)
      • Vagus: stretch, chemoreceptor, nociceptor; to vagal ganglia
      • Segmental (parallel to sympathetics) with spinal nerves; to cervical and thoracic dorsal root ganglia
      CLINICAL CORRELATES
  • Zenker’s Diverticulum
    • False (posterior) diverticulum
    • Occurs between the cricopharyngeus and the rest of the inferior constrictor
    • Caused by increased swallowing pressure
    • Symptoms: upper esophageal dysphagia, halitosis, choking
    • Treatment: cricopharyngeal myotomy, resected or suspended (without removal of diverticulum) via left cervical incision
    Traction Diverticulum
    • True diverticulum, typically lateral
    • Caused by granulomatous disease, chronic inflammation, or tumor
    • Typically in mid-esophagus
     
 
 
 

Gastroduodenal Disease and Anatomy


Gastric Microscopic Anatomy
  • Mucosa
    • Epithelium
      • Mucus-secreting cardia glands
      • Oxyntic glands in the fundus and body
        • Chief cells secrete pepsinogen
        • Parietal cells secrete H+ and intrinsic factor
      • Antrum and pylorus glands
        • Both secrete HC03 and mucus
        • G cells release gastrin
        • D cells secrete somatostatin, inhibiting release of gastrin and H+
anatomy of the Duodenum
Most fixed portion of small bowel, surrounds head of the pancreas

Duodenal Microscopic Anatomy
  • Mucosa
    • Epithelium: enterocytes (absorptive), goblet cells, Paneth cells, enterochromaffin cells
    • Lamina propria: contains Peyer’s patches (lymphoid aggregations with B cells in germinal centers and T cell in interfollicular zones)
    • Muscularis mucosa
    • Water and nutrients absorbed across the mucosa
  • Inner Surface
    • Mucosal surface area specializations: microvilli, villi, plica circulares (valvulae conniventes)
    • Total absorptive surface: 200-550 cm2
 
Gastroduodenal Embryology
  • Stomach has two mesenteries during development
  • Dorsal mesogastrium, attached to the greater curvature, grows very redundant, overlaps, and becomes the greater omentum
  • Ventral mesogastrium, part of the original septum transversum, becomes the following
    • Lesser omentum (hepatogastric ligament)
    • Peritoneal serosa of liver, gallbladder
    • Falciform ligament, with embedded round ligament of the liver
  • Greater curvature is initially dorsal, then the stomach rotates along its longitudinal axis until the dorsal curve lies to the left
  • Stomach also rotates around an axis through the gastroesophageal junction, until the greater curvature lies in its final left inferolateral position
  • Duodenum also rotates with the stomach, as well as around an anteroposterior axis, so that it surrounds the pancreas
  • First two parts of the duodenum (down to the bile duct), the terminal portion of the foregut: supplied by the celiac axis
  • Lower second through fourth parts of the duodenum, the initial segment of the midgut: supplied by the proximal superior mesenteric artery
Innervation
  • Parasympathetic
    • Left vagal trunk lies anterior as it crosses the gastroesophageal junction and runs anteriorly along the lesser curvature toward the duodenum
    • Right vagal trunk lies posterior as it crosses the gastroesophageal junction and runs posteriorly along the lesser curvature toward the duodenum
    • Ganglion cells are located in myenteric (Auerbach’s) and submucosal (Meissner’s) plexuses in stomach and duodenum
  • Sympathetic
    • Preganglionic fibers from T8-T10 lateral column distributed via splanchnic nerves
    • Postganglionic fibers are distributed from ganglion cells in celiac and superior mesenteric ganglia, traveling along respective arterial branches
  • Sensory fibers (general visceral afferent)
    • Vagal afferents, including stretch, chemo-, and "satiety" receptors
    • Segmental afferents travel back parallel to sympathetics, through the celiac and superior mesenteric plexuses and the splanchnic nerves to thoracic spinal nerves, dorsal root ganglia, and spinal segments
 Gastritis
  • Chronic
    • Type A: in fundus, associated with autoimmune disease and pernicious anemia
    • Type B: in antrum, associated with Helicobacter pylori
Peptic Ulcer :70%-80% in lesser curvature of the stomach   
 
Hiatal Hernia - - - - - - Figure
  • Type I: dilation of hiatus with sliding hernia; most common, may be associated with GERD, although most Type I patients do not reflux
  • Type II: paraesophageal, hole in diaphragm next to the esophagus; symptoms - dysphagia, chest pain, early satiety
  • Type III: combined
  • Type IV: entire stomach in thorax, other organs may be included (e.g., spleen or colon)