Diabetics get peripheral neuropathy from glucose damaging Schwann cells. For what I believe is an unconfirmed reason, T2DM patients tend to see parasympathetic autonomic neuropathy before sympathetic.

The hypogastric nerve carries sympathetic innervation to the posterior urethra and is responsible for ejaculation.

Inferior rectal nerve is a branch of the pudendal nerve that innervates the external anal sphincter and provides sensation below the pectinate line. A peripheral nerve problem with this nerve would cause the sphincter to remain relaxed and cause incontinence, not constipation.

Pelvic splanchnic nerves are parasympathetics (craniosacral outflow). If he is constipated, his rest and digest (parasympathetic) system is not working.

Perineal nerve is a branch of the pudendal nerve. It has both motor and sensory, is involved in the external anal sphincter, urethral sphincter, and is responsible for conscious sensation of the need to urinate.

Sacral sympathetic inhibits peristalsis, and contracts internal anal sphincter to maintain continence.

FA2019 p 357 on Gastrointestinal blood supply and parasympathetic innervation:

• Foregut --> celiac artery, vagus innervation
• Midgut --> SMA, vagus
• Hindgut --> IMA, pelvic innervation

Pelvic splanchnic nerves are part of the parasympathetic system.

o Greater Splanchnic (T5-T10)= Symp innervation foregut o Lesser Splanchnic (T9-T12)= Symp to hindgut o Vagus nerve= Parasymp of proximal GI system until splenic flexure o Pelvic Splanchnic (S2-S4)= Parasymp to bowel and bladder

Heres a summary of the Autonmomics of that area!