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 of the vagus nerve (n. vagus). Longitudinal plexuses, atrial plexuses, and ventricular plexuses are distinguished in the heart wall, containing ganglia (ganglia cardiaca) and neurons responsible for myocardial automatism, 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 the adaptation of motility to swallowing and the coordination of peristalsis.
Stomach and intestines
The stomach is innervated by branches of the celiac plexus and vagus nerves. Subserous, myenteric (plexus myentericus), and submucous (plexus submucosus) plexuses form within its wall. They are particularly prominent along the lesser and greater curvatures. These structures manage motility, blood supply, and gastric juice secretion.
The intramural plexuses of the intestine (small and large) originate from the superior and inferior mesenteric plexuses, vagus nerves, and pelvic splanchnic nerves (nn. splanchnici pelvici). The primary role here is also played by the myenteric and submucous plexuses, which are responsible for peristalsis, segmentation, secretion, and absorption processes.
Urogenital system
The plexuses of the urinary bladder originate from the vesical plexus (plexus vesicalis), which is connected to the inferior hypogastric plexus. Fibers enter in the region of the ureters and form superficial (subserous) and deep (intermuscular-mucosal) plexuses. They regulate detrusor tone and coordinate urination.
In the uterus, nerve elements are formed from 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.
The plexuses of the vagina 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 sensitivity.
Briefly: answers to topical questions
How do the influences of the sympathetic and parasympathetic nervous systems on gastric motility and secretion differ?
The influence of the autonomic nervous system on the stomach depends on its division. Sympathetic influence inhibits peristalsis. When sympathetic tone is eliminated, gastrointestinal motility and digestive gland secretion are enhanced, reflecting the predominance of parasympathetic innervation. The intramural plexuses of the stomach regulate motor activity and gastric gland 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 the intramural ganglia.
- Effector neurons (Type I cells) are long-process cells that serve as the final link in transmitting impulses to the working tissue.
- Sensory neurons (Type II cells) are equibranched multipolar cells whose dendrites form receptors in the organ tissue.
- Associative neurons (Type III cells) are 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. The centers of the parasympathetic nervous system that give rise to the preganglionic fibers of these nerves are located in the gray matter (in the lateral horns) at the level of segments S2–S4 (SII–SIV). These nerves provide parasympathetic innervation to the pelvic cavity organs, including the rectum and urinary bladder.
What nerve plexuses are distinguished in the heart wall?
Longitudinal plexuses, atrial plexuses, and ventricular plexuses are distinguished in 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 automatism, conduction, and contractile activity.
Class and exam questions
What are the main plexuses distinguished in the wall of the stomach and intestines?
In the wall of the stomach and intestines, the primary plexuses are the myenteric (plexus myentericus) and submucous (plexus submucosus) plexuses.
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 of the vagus nerves (n. vagus).
What function do the intramural plexuses of the urinary bladder perform?
They regulate detrusor tone, coordinate the act of urination, and adapt bladder function to filling and emptying.
What else to study on this topic
- Anatomy and topography of extra-organ cardiac plexuses
- Structure and functions of the myenteric (Auerbach's) plexus
- The submucous (Meissner's) nerve plexus and its role
- Connection of the inferior hypogastric plexus with pelvic organs
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