Lecture 70: Autonomics of the Abd and Pelvis

What does the somatic nervous system control?

Voluntary striated muscle of the body wall.

What does the visceral nervous system control?

Involuntary smooth muscle, cardiac muscle, and glands.

What are the two major components of the visceral motor (autonomic) system?

Sympathetic and parasympathetic divisions.

Where are visceral motor (preganglionic) neuron cell bodies located?

Inside the CNS (brainstem or spinal cord).

Where are visceral motor (postganglionic) neuron cell bodies located?

Outside the CNS in autonomic ganglia.

What is the difference between visceral sensory and somatic sensory input? 

Visceral sensory is dull, poorly localized, and associated with distension or ischemia; somatic sensory is sharp and well localized.

What spinal cord levels give rise to sympathetic preganglionic neurons?

T1–L2 lateral horn.

Through which nerves do sympathetic preganglionic axons reach abdominal and pelvic organs?

Thoracic, lumbar, and sacral splanchnic nerves.

Where are sympathetic postganglionic cell bodies located for abdominal organs?

In subdiaphragmatic (prevertebral / preaortic) ganglia near major arteries

How do sympathetic postganglionic axons reach their target organs? 

They follow the arterial branches that supply the same organs.

 What regions of the gut are supplied by each sympathetic ganglion? 

Celiac (foregut), superior mesenteric (midgut), inferior mesenteric (hindgut)

What spinal levels correspond to the foregut, midgut, and hindgut?

Foregut: T5–T9; Midgut: T9–T12; Hindgut: T12–L2.

What sympathetic nerves innervate the pelvic organs?

Lumbar and sacral splanchnic nerves

What are the sympathetic spinal levels for the stomach, liver, and gallbladder? 

Stomach T5–T9, Liver/Gallbladder T7–T9.

What are the sympathetic levels for kidneys and ureters? 

Kidneys T12–L2; Ureters T10–L2.

What are the sympathetic levels for the bladder and uterus?

Bladder T11–L2; Uterus T10–L1.

What are the sympathetic levels for ovaries/testes?

T12–L1 (postganglionics follow gonadal arteries).

Where are parasympathetic preganglionic neurons located?

Brainstem (via vagus nerve) and sacral spinal cord (S3–S4, sometimes S2–S5).

What is the parasympathetic supply to the foregut and midgut?

Vagus nerve (CN X)

What is the parasympathetic supply to the hindgut and pelvic organs? 

Pelvic splanchnic nerves (S3–S4)

Where are parasympathetic postganglionic neurons located? 

In or near the walls of the target organs.

Which pelvic plexus integrates sympathetic and parasympathetic fibers?

The inferior hypogastric plexus (and pelvic plexuses).

How does visceral sensory information travel to the CNS?

Usually follows sympathetic pathways back to the spinal cord.

What is the exception to visceral sensory pathways?

Organs below the pelvic pain line and reflex sensations follow parasympathetics (S3–S4).

What is referred pain?

Pain from an internal organ perceived as originating in a somatic region sharing the same spinal segment.

What explains scapular pain in gallstones?

Referred pain from the gallbladder (T7–T9 spinal level).

What nerve controls the detrusor muscle?

Pelvic splanchnic nerves (S3–S4).

What somatic muscles assist erection and ejaculation? 

Bulbospongiosus and ischiocavernosus muscles.

During childbirth, what nerves convey labor and delivery pain?

Uterine contractions (T10–L1), cervix (S3–S4), perineum (pudendal S2–S4).