Abdominal and pelvic autonomic plexuses and ganglias, enteric system
Abdominal and Pelvic Autonomic Plexuses and Ganglia, Enteric Nervous System
- Introduction:**
The autonomic nervous system (ANS) of the abdomen and pelvis controls involuntary physiological functions by integrating sympathetic and parasympathetic signals. It operates through a network of autonomic plexuses and ganglia. In addition, the enteric nervous system (ENS) provides local control over gastrointestinal function.
- Abdominal Autonomic Plexuses and Ganglia:**
The abdomen contains several interconnected autonomic plexuses organized around major blood vessels. These include:
- **Celiac plexus**: The largest autonomic plexus, located around the celiac trunk. It contains paired celiac ganglia and provides sympathetic and parasympathetic innervation to the foregut organs (e.g., stomach, liver, pancreas, spleen). - **Superior mesenteric plexus**: Located around the superior mesenteric artery. It continues from the celiac plexus and supplies the midgut (e.g., small intestine, proximal colon). - **Aorticorenal plexus**: Supplies the kidneys and adrenal glands and contains the aorticorenal ganglia. - **Inferior mesenteric plexus**: Surrounds the inferior mesenteric artery and innervates the hindgut (e.g., distal colon, rectum). - **Intermesenteric plexus**: A longitudinal network connecting the superior and inferior mesenteric plexuses.
Sympathetic fibers reach these plexuses through thoracic and lumbar splanchnic nerves, and synapse in prevertebral ganglia. Parasympathetic innervation arises from the vagus nerve (for foregut and midgut) and pelvic splanchnic nerves (S2–S4) for the hindgut.
- Pelvic Autonomic Plexuses and Ganglia:**
- **Superior hypogastric plexus**: Located anterior to the aortic bifurcation, continues into the pelvis as the hypogastric nerves. - **Inferior hypogastric plexus (pelvic plexus)**: Formed by hypogastric nerves and pelvic splanchnic nerves. It supplies the pelvic viscera including the bladder, rectum, and reproductive organs. It also contains small ganglia where sympathetic and parasympathetic fibers may synapse.
- Enteric Nervous System (ENS):**
The ENS is a subdivision of the ANS embedded in the wall of the gastrointestinal tract. It consists of two main plexuses: - **Myenteric (Auerbach’s) plexus**: Located between the longitudinal and circular layers of the muscularis externa. It controls peristalsis and gut motility. - **Submucosal (Meissner’s) plexus**: Found in the submucosa. It regulates local blood flow, secretions, and absorption.
The ENS can function autonomously but is influenced by both sympathetic (inhibitory) and parasympathetic (stimulatory) inputs.
- Conclusion:**
The abdominal and pelvic autonomic plexuses and ganglia form a complex control network for visceral organ function, integrating sympathetic and parasympathetic innervation. The ENS ensures intrinsic gastrointestinal regulation and represents a highly developed, semi-autonomous neural system.
- Sources:**
- Sobotta Atlas of Human Anatomy, 16th edition - Gray’s Anatomy for Students, 4th edition - Clinically Oriented Anatomy by Moore, 8th edition - Principles of Neural Science by Kandel et al., 5th edition
