The cavernous nerves are the terminal branches of the inferior hypogastric plexus carrying parasympathetic fibres responsible for erection. They arise from the pelvic plexus alongside the prostate in males (the neurovascular bundle of Walsh) and alongside the uterosacral ligaments in females, passing anterolaterally at the 5 and 7 o'clock positions relative to the prostate/rectum to reach the corporeal bodies of the penis or clitoris. Acetylcholine from parasympathetic endings stimulates NO release, producing smooth muscle relaxation and vascular engorgement.
The cavernous nerves are the critical structures preserved in nerve-sparing radical prostatectomy: the neurovascular bundles containing the cavernous nerves run in the fascial planes between the prostate and the rectum (Denonvilliers fascia) and between the prostate and the levator ani. Nerve-sparing technique preserves the fascial envelope around the neurovascular bundle by dissecting in the interfascial or intrafascial plane. Post-prostatectomy erectile dysfunction correlates directly with cavernous nerve preservation; with bilateral nerve-sparing, 60-70% of pre-operatively potent men recover erections by 2 years.
Standard non-nerve-sparing radical prostatectomy sacrifices the neurovascular bundles at the 5 and 7 o'clock positions around the prostate, dividing the cavernous nerves and producing complete erectile dysfunction; nerve-sparing technique dissecting in the intrafascial plane preserves the cavernous nerves and improves erectile function recovery to 60-70% at 2 years post-surgery.
