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Autonomic Innervation of Internal Organs

For medical students2 min readUpdated 2026-10-10

The autonomic innervation of internal organs is provided by a complex system of intramural nerve plexuses. Both sympathetic and parasympathetic fibers participate in their formation, penetrating the organ wall to regulate its automaticity, motility, secretion, and tone.

HeartRegulates myocardial automaticity and conduction.
Digestive tractCoordinates peristalsis, secretion, and absorption.
Urinary bladderControls detrusor muscle tone and micturition.
Reproductive systemManages myometrial tone and vascular responses.

Heart and Esophagus

The intramural plexuses of the heart are a continuation of extra-organ plexuses. They are formed by sympathetic fibers from the cervical and upper thoracic ganglia, as well as parasympathetic fibers from the vagus nerve (n. vagus). Longitudinal plexuses, atrial plexuses, and ventricular plexuses are distinguished within the heart wall; these contain ganglia (ganglia cardiaca) and neurons responsible for myocardial automaticity, conduction, and contraction.

In the esophagus, plexuses are formed by branches of the vagus nerves and sympathetic fibers from the thoracic ganglia. They merge into the esophageal plexus (plexus oesophageus), from which they penetrate the organ wall, lying predominantly in the submucosa and between the muscle layers. Their main function is to adapt motility to swallowing and coordinate peristalsis.

Stomach and Intestines

The stomach is innervated by branches of the celiac plexus and vagus nerves. Subserosal, myenteric (plexus myentericus), and submucosal (plexus submucosus) plexuses form within its wall. These are particularly prominent along the lesser and greater curvatures. These structures regulate motility, blood supply, and gastric acid secretion.

The intramural plexuses of the intestines (small and large) originate from the superior and inferior mesenteric plexuses, vagus nerves, and pelvic splanchnic nerves (nn. splanchnici pelvici). The myenteric and submucosal plexuses play the primary role here, controlling peristalsis, segmentation, secretion, and absorption.

Urogenital System

Plexuses of the urinary bladder originate from the vesical plexus (plexus vesicalis), which is connected to the inferior hypogastric plexus. Fibers enter near the ureters, forming superficial (subserosal) and deep (intermuscular-mucosal) plexuses. They regulate detrusor tone and coordinate urination.

In the uterus, neural elements are formed by the uterovaginal plexus (plexus uterovaginalis), a derivative of the inferior hypogastric plexus. The most developed ganglia are located in the body and fundus of the uterus, controlling myometrial tone and cyclic changes.

Vaginal plexuses also originate from the uterovaginal plexus, forming a dense network in the submucosal layer. Branches of the vaginal nerves (nn. vaginales) create loops with ganglia that anastomose with the rectal and vesical plexuses, providing autonomic control and sensation.

Frequently asked questions

How do sympathetic and parasympathetic inputs differentially affect gastric motility and secretion?

The autonomic influence on the stomach depends on the division involved. Sympathetic input inhibits peristalsis. When sympathetic tone is removed, gastrointestinal motility and digestive gland secretion increase, reflecting the predominance of parasympathetic innervation. Intramural gastric plexuses regulate motor activity and gastric juice secretion.

What types of neurons (Dogiel cells) are distinguished in the intramural ganglia of the intestine?

According to Dogiel's classification, three types of neurons are distinguished in intramural ganglia:

  • Effector neurons (Type I cells) — long-process cells that serve as the final link in transmitting impulses to the effector tissue.
  • Sensory neurons (Type II cells) — equal-process multipolar cells whose dendrites form receptors in the organ tissue.
  • Association neurons (Type III cells) — interneurons that receive signals from sensory neurons and transmit them to effectors.
From which spinal cord segments do the pelvic splanchnic nerves (nn. splanchnici pelvici) originate?

The pelvic splanchnic nerves (nn. splanchnici pelvici) originate from the sacral segments of the spinal cord. Parasympathetic centers giving rise to the preganglionic fibers of these nerves are located in the gray matter (lateral horns) at the S2–S4 (SII–SIV) spinal levels. These nerves provide parasympathetic innervation to pelvic organs, including the rectum and urinary bladder.

What nerve plexuses are distinguished within the heart wall?

Longitudinal plexuses, atrial plexuses, and ventricular plexuses are distinguished within the heart wall. Intramural plexuses contain nerve fibers of varying thickness, numerous intramural ganglia (ganglia cardiaca), and individual nerve cells. These plexuses are closely interconnected and regulate myocardial automaticity, conduction, and contractility.

What are the main nerve plexuses found in the wall of the stomach and intestines?

The main plexuses in the wall of the stomach and intestines are the myenteric plexus (plexus myentericus) and the submucosal plexus (plexus submucosus).

Where does the heart receive its innervation from?

The heart is innervated by sympathetic fibers from the cervical and upper thoracic ganglia of the sympathetic trunk and parasympathetic fibers from the vagus nerves (n. vagus).

What function do the intramural plexuses of the urinary bladder perform?

They regulate detrusor tone, coordinate the act of micturition, and adapt bladder function to filling and emptying.

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