The esophageal musculature is unique in its transition from voluntary striated muscle in the upper esophagus to involuntary smooth muscle in the lower esophagus. Primary peristalsis is triggered by swallowing; secondary peristalsis (autonomous esophageal reflex) clears residual food without conscious swallowing. Achalasia is the paradigm of esophageal motor disorder — absent peristalsis with failed LES relaxation from myenteric plexus degeneration.
| Origin | Upper third: striated (skeletal) muscle from the cricopharyngeus continuously (transitioning to smooth muscle at the level of the aortic arch); Middle third: mixed striated and smooth; Lower third: smooth muscle only (circular inner layer and longitudinal outer layer) |
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| Insertion | Continuous with the gastric musculature at the gastroesophageal junction; the longitudinal layer connects to the cricopharyngeus superiorly |
| Nerve Supply | Upper third: recurrent laryngeal nerve and vagus (via pharyngeal plexus); Lower two-thirds: vagus nerve (CN X) myenteric plexus; Sympathetic via thoracic sympathetic chain |
| Blood Supply | Superior: inferior thyroid artery; Middle: oesophageal branches of descending aorta; Lower: left gastric artery |
| Actions | Primary peristaltic contraction propels the food bolus from the pharynx to the stomach through coordinated circular muscle contraction behind the bolus and longitudinal muscle shortening ahead of it; the longitudinal muscle shortens the esophagus to allow the peristaltic ring to advance distally |
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Esophageal motility disorders are classified by high-resolution manometry: achalasia (absent peristalsis, elevated LES pressure), distal esophageal spasm, hypercontractile esophagus (jackhammer), and ineffective esophageal motility. Achalasia type I (absent peristalsis, dilated esophagus) vs type II (panesophageal pressurisation) vs type III (spastic) guides treatment: pneumatic dilation, Heller myotomy (divides the lower esophageal smooth muscle circular layer), or POEM (per-oral endoscopic myotomy through the submucosal tunnel). The striated muscle of the upper esophagus is innervated by the RLN, explaining the dysphagia in recurrent laryngeal nerve palsy.
Loss of inhibitory myenteric plexus neurons in the distal esophageal smooth muscle produces absent peristalsis and failed LES relaxation, causing progressive dysphagia and esophageal dilation; POEM (peroral endoscopic myotomy) creates a 10-15 cm myotomy of the circular muscle layer through a submucosal tunnel providing durable symptom relief comparable to surgical Heller myotomy.
