From the Research
The lower esophagus is primarily innervated by the vagus nerve, which provides parasympathetic input regulating peristalsis and lower esophageal sphincter function, with sympathetic innervation from the thoracic sympathetic chain serving sensory functions and regulating blood vessels. The innervation of the lower esophagus is complex, involving both extrinsic and intrinsic nervous systems. The vagus nerve, specifically its anterior and posterior vagal trunks, provides the primary parasympathetic innervation to the smooth muscle of the lower esophagus, controlling peristalsis and lower esophageal sphincter (LES) function 1.
The sympathetic innervation, derived from the thoracic sympathetic chain, particularly the greater splanchnic nerve originating from T5-T9 spinal segments, primarily serves sensory functions, including pain transmission, and regulates blood vessels in the esophageal wall. The intrinsic innervation involves the myenteric (Auerbach's) plexus and submucosal (Meissner's) plexus, containing local reflex circuits that can coordinate some esophageal functions without central nervous system input.
Key points about the innervation include:
- The vagal pathways are essential for reflex relaxation of the lower esophageal sphincter, such as during transient LES relaxations 1.
- Vagal afferent sensory endings from the distal esophagus and LES terminate in the hindbrain nucleus tractus solitarius, and the preganglionic motor innervation of the LES arises from the dorsal motor nucleus of the vagus 1.
- The motor vagal preganglionic output is primarily cholinergic, stimulating excitatory or inhibitory motor neurons that control smooth muscle tone, with excitatory neurons evoking muscarinic receptor-mediated muscle contraction and inhibitory neurons evoking nitric oxide or vasoactive intestinal polypeptide-mediated relaxation of the LES 1.
- Other neurotransmitters found in vagal preganglionic neurons include norepinephrine/dopamine and nitric oxide, with a subpopulation of nitric oxide synthase-containing vagal preganglionic neurons innervating the upper gastrointestinal tract and mediating relaxation 1.
This dual innervation is clinically significant in conditions like achalasia, gastroesophageal reflux disease, and esophageal pain syndromes, where dysfunction in these neural pathways can lead to motility disorders or altered sensation. The most recent and highest quality evidence supports the critical role of the vagus nerve in regulating lower esophageal sphincter function and esophageal peristalsis, highlighting the importance of considering these neural pathways in the diagnosis and treatment of esophageal disorders 2.