Things you should know about Surgical Anatomy of the Rectum, but don't dare to ask

How is the rectum/anus complex irrigated?

What is the composition of the venous drainage of the rectum/anus complex?

How is the rectum/anus complex innervated?

To answer the questions:

HOW IS THE RECTUM/ANUS COMPLEX IRRIGATED?

The arterial irrigation of the rectum anus complex has 4 pedicles:

• Superior Rectal
• Middle Rectal
• Inferior Rectal
• Median Sacral

It is important to remember that not all branches are constant

WHAT IS THE COMPOSITION OF THE VENOUS DRAINAGE OF THE RECTUM/ANUS COMPLEX?

The venous drainage of the rectum anus is composed of 3 plexuses.

• Internal venous plexus
• Perimuscular venous plexus
• External venous plexus

There is communication between the different venous plexuses.

It is important to remember that the first plexus drains into the portal system and the last two into the inferior vena cava system.

HOW IS THE RECTUM/ANUS COMPLEX INNERVATED?

The rectum/anus complex is innervated by fibers originating in the superior and inferior hypogastric plexus, all of them arriving at the Lee Frankenhausen ganglia, which give off multiple branches. One of them is the rectal branch.

The innervation of the rectum anus consists of 2 components:

• The Sympathetic component is responsible for inhibiting rectal peristalsis and stimulates the internal anal sphincter.
• The Parasympathetic component is responsible for stimulating the rectal peristalsis (defecation) and inhibits the internal anal sphincter.