AUTONOMIC NERVE SUPPLY OF THE COLON AND RECTUM

There are two components

a)      Sympathetic nerve supply –

i)                    Right Colon – Originates from the lower 6 lumbar spinal segments and form a ganglionic chain behind the IVC, from whence it distributes via the blood vessels.

ii)                   Left Colon – Originates from the upper three lumbar spinal segment and form a ganglionic chain on the side of the aorta. Fibres leave the chain to form a plexus (the hypogastric plexus) around the inferior mesenteric arteries. From here the nerves follow the blood vessels.

iii)                 Pelvic viscera – Preganglionic fibres converge on the anterior aspect of the aortic bifurcation to form the hypogastric plexus where they get a contribution from the nervi erigentes and thence pass down as two hypogastric nerves or presacral nerves. It runs laterally to the side wall of the pelvis where it is in close relation with the middle rectal artery at its origin from the Internal Iliac artery [There are other variant origins of the middle rectal]. It then supplies the penis, vagina, urethra, prostate, seminal vesicles, base of bladder, rectum and anus.

b)      Parasympathetic nerve supply –

i)                    Right Colon – Probably from the Posterior Vagus, from where fibres join the superior mesenteric plexus.

ii)                   Rest of the colorectum – Is derived from S2-4. Emerges from the sacral foramina and behind the Waldeyer’s fascia. Proceeds laterally and onto the side wall of the pelvis as Nervi erigentes where it joins the presacral nerves. It also gives off a branch to the hypogastric plexus at the aortic bifurcation and then supplies the sigmoid and descending colon.

SITES OF DAMAGE

1)      Nervi erigentes lies behind the Waldeyer’s fascia and can be damaged if the presacral fascia is stripped.

2)      Damage to the presacral nerve may also occur during clearance of the internal iliac artery for malignancy or lateral division of the lateral ligaments.

3)      Some fibres may be damaged in front of the aortic bifurcation.

4)      Inferior mesenteric ganglia can be damaged at the root of the Inferior mesenteric artery during a flush ligation and division of the IMA.