Gastrointestinal Flashcards
Trigeminal nerve:
Nasopharynx
Glossopharyngeal nerve:
Posterior third of the tongue and oral pharynx
Superior laryngeal nerve
base of tongue and inferior epiglottis to the vocal cords
Recurrent laryngeal nerve
vocal cords distally
Branches of the Vagus nerve
Remaining larynx and trachea
The esophagus originates at the pharynx at approximately what cervical level?
C6 and extends to the stomach
3 functional zones:
- upper esophageal sphincter
- esophageal body
- lower esophageal sphincter
Passes through a space created by the Right crus of the diaphragm
Layers of the esophageal wall:
- Outer longitudinal layer
- Inner circular muscular layer of smooth and striated muscle
- mucosal lining
- squamous epithelium
- except for distal 1-2 cm which is composed of columnar epithelium
Blood supply to esophagus:
- Interior thyroid arteries: cervical esophagus
- Aortic esophageal branches of bronchial arteries: thoracic esophagus
Intrinsic innervation of the gut (also known as the Enteric Nervous system):
2 interconnected plexuses:
- Myenteric or Auerback plexus
- Submucosal or Meissner plexus
- This system extends from the esophagus to anus.
- The enteric nervous system can operate autonomously, although the autonomic NS (PNS and SNS) can influence functions.
Extrinsic Innervation of the gut (Autonomic NS):
Sympathetic: “gastroparesis” fight or flight, slows gut.
-Acts on myenteric plexus to modulate rather than control motor activity
Parasympathetic: “Speeds up” rest and digest
-Cranial nerves IX Glossalpharyngeal, X Vagus, XI Accessory. Mostly the Vagus nerve.
Normal esophageal function:
-Both the upper and lower esophageal sphincters are closed at rest.
- Velocity of swallowing: 3-4cm/sec
- maximum pressure 150mmHg
Lower esophageal sphincter tone:
- swallowing decreases LES tone within 1.5-2.5 seconds and is maintained over the duration of the peristaltic wave (6-8 seconds)
- Normal LES tone is 20mmHg
- Vagal innervation is predominant.
Dysphagia:
Difficulty swallowing.
Barium swallow study
Upper endoscopy
Problems associated with Chronic EtOH:
- impaired esophageal peristalsis
- LES hypotonia (weak)
- Degeneration of Auerbach plexus (Intrinsic innervation)
- Mallory weis tear
Achalasia:
-Failure of the lower esophageal sphincter tone to relax during swallowing accompanied by a lack of peristalsis.
Conditions associated with Achalasia:
- DM
- Stroke
- Amyotrophic lateral sclerosis (ALS, Lou Gehrig’s dx)
- Connective tissue diseases (amyloidosis, scleroderma)