Pelvic splanchnic nerves
Pelvic splanchnic nerves or nervi erigentes are splanchnic nerves
Splanchnic nerves
The splanchnic nerves are paired nerves that contribute to the innervation of the viscera, carrying fibers of the autonomic nervous system as well as sensory fibers from the organs...

 that arise from sacral spinal nerve
Spinal nerve
The term spinal nerve generally refers to a mixed spinal nerve, which carries motor, sensory, and autonomic signals between the spinal cord and the body...

s S2
Sacral spinal nerve 2
The sacral spinal nerve 2 is a spinal nerve of the sacral segment..It originates from the spinal column from below the 2nd body of the sacrum -Muscles:...

, S3
Sacral spinal nerve 3
The sacral spinal nerve 3 is a spinal nerve of the sacral segment..It originates from the spinal column from below the 3rd body of the sacrum -Muscles:...

, S4
Sacral spinal nerve 4
The sacral spinal nerve 4 is a spinal nerve of the sacral segment..It originates from the spinal column from below the 4th body of the sacrum -Muscles:...

 to provide parasympathetic innervation to the hindgut
The hindgut is the posterior part of the alimentary canal. In mammals, it includes the distal third of the transverse colon and the splenic flexure, the descending colon, sigmoid colon and rectum.-Blood flow:...



The pelvic splanchnic nerves arise from the ventral rami of the S2-S4 and enter the sacral plexus. They travel to their side's corresponding inferior hypogastric plexus
Inferior hypogastric plexus
The inferior hypogastric plexus is a plexus of nerves that supplies the viscera of the pelvic cavity.The inferior hypogastric plexus is a paired structure, with each situated on the side of the rectum in the male, and at the sides of the rectum and vagina in the female.-Sources:Contributions to...

, located bilaterally on the walls of the rectum.

From there, they contribute to the innervation of the pelvic
In human anatomy, the pelvis is the lower part of the trunk, between the abdomen and the lower limbs .The pelvis includes several structures:...

 and genital organs. The nerves regulate the emptying of the urinary bladder
Urinary bladder
The urinary bladder is the organ that collects urine excreted by the kidneys before disposal by urination. A hollow muscular, and distensible organ, the bladder sits on the pelvic floor...

 and the rectum
The rectum is the final straight portion of the large intestine in some mammals, and the gut in others, terminating in the anus. The human rectum is about 12 cm long...

 as well as sex
In biology, sex is a process of combining and mixing genetic traits, often resulting in the specialization of organisms into a male or female variety . Sexual reproduction involves combining specialized cells to form offspring that inherit traits from both parents...

ual functions like erection
Penile erection is a physiological phenomenon where the penis becomes enlarged and firm. Penile erection is the result of a complex interaction of psychological, neural, vascular and endocrine factors, and is usually, though not exclusively, associated with sexual arousal...


They contain both preganglionic parasympathetic fibers as well as visceral afferent fibers.

The parasympathetic nervous system
Parasympathetic nervous system
The parasympathetic nervous system is one of the two main divisions of the autonomic nervous system . The ANS is responsible for regulation of internal organs and glands, which occurs unconsciously...

 is referred to as the craniosacral outflow; the pelvic splanchnic nerves are the sacral component. They are in the same region as the sacral splanchnic nerves
Sacral splanchnic nerves
Sacral splanchnic nerves are splanchnic nerves that connect the inferior hypogastric plexus to the sympathetic trunk in the pelvis.-Structure:...

, which arise from the sympathetic trunk
Sympathetic trunk
The sympathetic trunks are a paired bundle of nerve fibers that run from the base of the skull to the coccyx.-Structure:...

 and provide sympathetic efferent fibers.

The proximal 2/3 of the transverse colon
Transverse colon
The transverse colon, the longest and most movable part of the colon, passes with a downward convexity from the right hypochondrium region across the abdomen, opposite the confines of the epigastric and umbilical zones, into the left hypochondrium region, where it curves sharply on itself beneath...

, and the rest of the proximal gastrointestinal tract
Gastrointestinal tract
The human gastrointestinal tract refers to the stomach and intestine, and sometimes to all the structures from the mouth to the anus. ....

 is supplied its parasympathetic fibers by the vagus nerve
Vagus nerve
The vagus nerve , also called pneumogastric nerve or cranial nerve X, is the tenth of twelve paired cranial nerves...

. In the distal 1/3 of the transverse colon, and through the sigmoid and rectum, the pelvic splanchnic nerves take over.
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