AUTONOMICS

What is the 2-neuron chain in autonomics?

preganglionic neuron (CNS origin) + postganglionic neuron (ganglion → target organ)

Where are sympathetic vs parasympathetic preganglionic neurons located?

• sympathetic - T12-L2

• parasympathetic - brainstem + S3-S4

What connects spinal nerves to sympathetic chain?

white and gray rami communicantes

Where do sympathetic preganglionics to abdomen/pelvis arise?

• lateral horn, T5-L2

• exit via thoracic/lumbar/sacral splanchnic nerves.

How is gut tube divided?

foregut, midgut, hindgut

Landmark separating midgut from hindgut?

distal 1/3 of transverse colon

What is the “5-4-3 rule” for sympathetics?

• foregut - T5-T9

• midgut - T9-T12

• hindgut - T12-L2

Which ganglion supplies the foregut?

celiac ganglion

How do postganglionic sympathetics reach target organs?

arterial branches (celiac trunk, SMA, IMA)

Which artery supplies the midgut (and carries autonomics)?

superior mesenteric artery

What ganglia cluster near renal arteries?

aorticorenal ganglia

What plexus sits at the aortic bifurcation?

superior hypogastric plexus

Do abdominal sympathetics synapse in paravertebral ganglia?

no, they pass through as splanchnic nerves to prevertebral ganglia.

How are splanchnic nerves named?

paravertebral ganglion level of exit (thoracic, lumbar, sacral).

What are the levels of the greater splanchnic nerve?

T5-T9

Which spinal cord levels supply lumbar/sacral splanchnics?

L1-L2 preganglionics descend to L1-L5 or sacral ganglia

Trace out the sympathetic pathway.

preganglionic (T5-L2) → splachnic nerve → prevertebral ganglion → follow artery → organ

At what level is appendix sympathetic innervation?

T10 (classic referred pain)

Sympathetic innervation of gallbladder?

T7-T9 → greater splanchnic → celiac ganglion → cystic artery

Preganglionic levels for ovaries?

T12-L1

Sympathetic innervation levels for uterus?

T10-L1 via hypogastric/pelvic plexus

How do testicular sympathetics travel?

via testicular artery (T12-L1 origin)

Where do sympathetics for prostate originate?

T12-L2 via hypogastric plexus

Sources of parasympathetic preganglionics?

vagus nerve (foregut/midgut), S3-S4 pelvic splanchnics (hindgut/pelvis)

Parasympathetics to hindgut?

pelvic splanchnic nerves (S3-4)

How do vagal trunks enter abdomen?

anterior/posterior trunks via esophageal plexus through diaphragm

Which nerves are parasympathetic from sacral region?

pelvic splanchnic nerves (S3-S4)

What fibers mix in pelvic plexus?

sympathetic + parasympathetic + visceral sensory

Effect of sympathetics vs parasympathetics on gut motility?

• sympathetic = decrease motility

• parasympathetic = increase motility

What triggers visceral pain?

ischemia, distension, cramping, inflammation (not cutting).

Where are visceral sensory neuron cell bodies?

dorsal root ganglia

Above vs below pelvic pain line sensory pathway?

• above = sympathetics

• below = parasympathetics (S3-S4).

Why does referred pain occur?

visceral afferents converge with somatic afferents at same spinal level

Early appendicitis pain dermatome?

T10 (umbilicus)

Referred pain of gallstones?

right lower ribs/scapula (T7-T9)

3 Sources of pain in labor/delivery?

• uterine contractions (T10-L1)

• cervical distension (S3-S4)

• perineal stretch (pudendal S2-S4)

Parasympathetic control of bladder?

pelvic splanchnic nerves (S3-S4) contract detrusor

Which autonomic divisions control erection vs ejaculation?

• parasympathetic - erection

• sympathetic - ejaculation

Nerve innervating detrusor muscle?

pelvic splanchnic nerves

What did Espinosa-Medina propose about sacral outflow?

• developmentally sympathetic, not parasympathetic

• not testable

What is the alternative view on sacral outflow?

• distinction is cranial vs spinal, not symp vs parasymp

• not testable

Where do sympathetic preganglionics for abdomen/pelvis originate?

T5-L2 lateral horn

Parasympathetic outflow regions?

• vagus (fore/midgut)

• S3-S4 (hindgut/pelvis)

Exception to “visceral sensory follows sympathetics’?

pelvic organs below pain line → parasympathetics