*2.6.2 Pelvic splanchnic nerves*

The pelvic splanchnic nerves are considered to be parasympathetic nerves that arise from the second to fourth sacral spinal nerves. These nerves enter the pelvis through the sacral foramen, posterior to the parietal fascia that covers the piriformis

#### **Figure 13.**

*Hypogastric nerves. The hypogastric nerves run from the superior hypogastric plexus and descend to the pelvic cavity and meet the pelvic splanchnic nerves.*

*Pelvic Anatomy for Distal Rectal Cancer Surgery DOI: http://dx.doi.org/10.5772/intechopen.99120*

#### **Figure 14.**

*Pelvic splanchnic nerves. The pelvic splanchnic nerves arise from the S2 to S4 spinal nerves. Small branches of the pelvic splanchnic nerves run medially and enter the mesorectum.*

muscle and crosses the retrorectal space, to enter the visceral compartment through the visceral fascia about 4 cm from the midline. Small branches of the pelvic splanchnic nerves run medially and enter the mesorectum (**Figure 14**). These nerves regulate the emptying of the urinary bladder and influence erectile functions and motility of the rectum. Therefore, damage to these nerves causes erectile dysfunction and decreased blood flow to the vagina and vulva, which can reduce vaginal lubrication.

### *2.6.3 Inferior hypogastric (pelvic) plexus*

The pelvic splanchnic nerves meet the hypogastric nerves and form the inferior hypogastric plexus at the lateral pelvic wall. It lies outside the fascia propria in the superficial layer of the parietal fascia. The inferior hypogastric plexus can be observed as a mesh-like structure at the posterolateral pelvic wall close to the prostate and seminal vesicles. Because the inferior hypogastric plexus consists of both sympathetic and parasympathetic efferent fibers, any damage to this plexus may cause severe disturbances in urogenital and sexual function including erection and ejaculation. It extends forward to form neurovascular bundles running down the seminal vesicle at 2 o'clock and 10 o'clock direction (**Figure 15**).

#### **Figure 15.**

*Inferior hypogastric (pelvic) plexus. The inferior hypogastric (pelvic) plexus is a network of sympathetic and parasympathetic fibers arising from the hypogastric nerves and the pelvic splanchnic nerves. It can be observed as a mesh-like structure at the posterolateral pelvic wall. It extends forward to form neurovascular bundles running down the seminal vesicle on both sides.*

These neurovascular bundles run through the posterolateral border of the prostate and continue to the periprostatic plexus, which supplies to the prostate, seminal vesicles, corpi cavernosi, and the vas deferens [15, 36]. Injury to the neurovascular bundles during anterior dissection may cause urinary and sexual dysfunction. Meticulous dissection is required because nerve damage may occur when surgery is performed along the wrong plane or excessive traction is performed.
