The mesenteric plexus refers to one of two crucial networks of nerves within the sympathetic nervous system, primarily located in the mesentery, which are vital for regulating various functions of the digestive organs.
These intricate nerve networks are part of the broader autonomic nervous system, which controls involuntary bodily functions. They are specifically situated in close proximity to, and distribute nerve fibers to, the same structures supplied by their corresponding mesenteric arteries.
Location and Structure
A nerve plexus is essentially a complex web or network of intersecting nerve fibers and associated ganglia (clusters of nerve cell bodies). The mesenteric plexuses are deeply embedded within the mesentery, a fold of peritoneum that attaches the intestine to the posterior wall of the abdomen, holding it in place.
These plexuses serve as important relay stations for sympathetic nerve impulses targeting the abdominal viscera, particularly parts of the gastrointestinal tract.
Types of Mesenteric Plexuses
While the term "mesenteric plexus" can generally refer to any of these networks, there are two primary divisions recognized based on their arterial association:
- Superior Mesenteric Plexus: This major plexus is associated with the superior mesenteric artery and provides sympathetic innervation to structures derived from the midgut, including the small intestine, cecum, ascending colon, and most of the transverse colon.
- Inferior Mesenteric Plexus: As specified, this plexus is associated with the inferior mesenteric artery and is responsible for innervating structures derived from the hindgut, such as the descending colon, sigmoid colon, rectum, and superior part of the anal canal.
| Feature | Superior Mesenteric Plexus | Inferior Mesenteric Plexus |
|---|---|---|
| Associated Artery | Superior Mesenteric Artery | Inferior Mesenteric Artery |
| Innervated Regions | Small intestine, cecum, ascending colon, transverse colon | Descending colon, sigmoid colon, rectum, superior anal canal |
| Primary Function | Sympathetic control of midgut structures | Sympathetic control of hindgut structures |
Role in the Body
The primary function of the mesenteric plexuses is to transmit sympathetic nerve signals to the digestive organs. This sympathetic innervation plays a crucial role in:
- Regulating Blood Flow: Controlling the constriction and dilation of blood vessels within the gastrointestinal tract, thus modulating blood supply to different sections of the intestines based on physiological needs.
- Modulating Gut Motility: Influencing the muscular contractions (peristalsis) that move food through the digestive system. Sympathetic activation generally inhibits gut motility.
- Controlling Glandular Secretions: Affecting the release of digestive enzymes and other substances from various glands within the digestive system.
Understanding the mesenteric plexuses is fundamental in comprehending the complex neural control over digestion and abdominal organ function.
