Innervation of Organs

Question 1

To targets in abdomen

Answer 1

Cell bodies of preganglionic neurons in vagus nerve nucleus in brainstem → Preganglionic nerves in vagus run to thorax and abdomen (long – wrap around esophagus) → synapse in terminal ganglia (typically in wall of organ being innervated) → postganglionic run just within wall of organ

Question 2

Innervation of large intestine (Sympathetic L colic flexure to rectum)

Answer 2

Sympathetic:

• • Lumbar splanchnic (preganglionic) to inferior mesenteric ganglia (collateral ganglia)
• • Postganglionic follow arteries in periarterial nerve plexus

Question 3

Sympathetic to lungs

Answer 3

cell bodies in lateral horn of upper thoracic spinal cord → preganglionic travel in ventral rootlets → ventral root → spinal nerve → anterior rami → white rami communicans → sympathetic chain ganglia (maybe up or down a little) → synapses in thoracic ganglia of the sympathetic chain → postganglionic go in visceral branches to the lungs (NOT through gray rami communicans)

Question 4

Parasympathetic to targets in head

Answer 4

Cell bodies of preganglionic neurons in cranial nerve nuclei in brainstem → Preganglionic nerves most of the way to the target (longish) → synapse in one of 4 cranial ganglia → postganglionic nerves run rest of way to target (short) → smooth muscle, gland, organ

Question 5

Innervation of small intestine

Answer 5

Parasympathetic:
– Vagus nerves (preganglionic) to terminal ganglia within intestinal wall
Sympathetic:
– Thoracic splanchnic (preganglionic) to celiac and superior mesenteric ganglia (collateral ganglia) (lesser thoracic splanchnic)
– Postganglionic follow arteries in periarterial nerve plexus
Visceral afferent:
– Travel with sympathetic and parasympathetic neurons

Question 6

Sympathetic to blood vessels, sweat glands and arrector pilli muscles

Answer 6

cell bodies in lateral horn of thoracolumbar spinal cord → preganglionic travel in ventral rootlets → ventral root → spinal nerve → anterior rami → white rami communicans → sympathetic chain ganglia → (maybe up or down) → synapse in sympathetic chain → postganglionic run through grey rami communicans → spinal nerve → out anterior rami for anterior/lateral/limb structures, out posterior rami for posterior neck/back structures

Question 7

Innervation of large intestine (Parasymp. L colic flexure to anal canal)

Answer 7

Parasympathetic:

• • Pelvic splanchnic (preganglionic) to terminal ganglia within intestinal wall
    
    • • Travel through inferior hypogastric plexuses (sympathetic and parasympathetic) and then follow branches of the inferior mesenteric artery (sup. rectum) or internal iliac artery

Question 8

To targets in pelvis

Answer 8

Cell bodies of preganglionic neurons in lateral/ventral horn of sacral spinal cord → ventral root → spinal nerve → anterior rami → pelvic splanchnic nerves to wall of target organ → synapse in terminal ganglia (typically in wall of organ being innervated) → postganglionic run within wall of organ

Question 9

Sympathetic to adrenal medulla

Answer 9

cell bodies in lateral horn of lower thoracic and upper lumbar spinal cord → preganglionic travel in ventral rootlets → ventral root → spinal nerve → anterior rami → white rami communicans → sympathetic chain ganglia → thoracic splanchnic (greater) → pass through ciliac ganglion → adrenal medulla → within adrenal medulla, synapse onto neurons that release norepinephrine and epinephrine into bloodstream

Question 10

Innervation of large intestine (visceral afferent)

Answer 10

Visceral afferent:

– travel with sympathetic and parasympathetic neurons

Question 11

Innervation of large intestine (Sympathetic rectum to anal canal)

Answer 11

Sympathetic:

• • Sacral splanchnic nerves
    
    • • Postganglionic from sacral sympathetic trunk to inferior hypogastric plexus and then follow branches of internal iliac artery
    • • Preganglionic to inferior hypogastric anglia; postganglionic then follow branches of internal iliac artery

Question 12

Innervation of pancreas, liver and gallbladder

Answer 12

Parasympathetic:
– Vagus (peganglionic) to terminal ganglia within wall of target organ
Sympathetic:
– Thoracic splanchnic (preganglionic) to celiac (greater) and superior mesenteric (lesser) ganglia (collateral ganglia)
– Postganglionic follow arteries in periarterial nerve plexus
Visceral sensory:
– Travel with sympathetic and parasympathetic neurons

Question 13

Sympathetic to pelvis

Answer 13

cell bodies in lateral horn of upper lumbar spinal cord → preganglionic travel in ventral rootlets → ventral root → spinal nerve → anterior rami → white rami communicans → sympathetic chain (go down) → either
A. Synapse in sacral sympathetic chain ganglia → sacral splanchnics → pass through inferior hypogastric ganglion → become part of plexuses and follow arteries to target
B. Pass through sympathetic chain ganglion → sacral splanchnics → synapse in inferior hypogastric ganglion → postganglionic become part of plexuses and follow arteries to target

Question 14

Sympathetic to abdomen/ upper pelvic

Answer 14

cell bodies in lateral horn of lower thoracic and upper lumbar spinal cord → preganglionic travel in ventral rootlets → ventral root → spinal nerve → anterior rami → white rami communicans → pass through sympathetic chain ganglia → travel in thoracic or lumbar splanchnic nerves to collateral ganglia (either celiac, aorticorenal, superior mesenteric or inferior mesenteric) → synapse in one of the 4 collateral ganglia (depends on target) → postganglionic neurons become part of plexuses (names depend on ganglia) → travel on arteries to target

Question 15

Innervation of kidneys

Answer 15

Parasympathetic:
– Vagus nerves (preganglionic) to terminal ganglia with wall
Sympathetic:
– Thoracic splanchnic (preganglionic) to aorticorenal ganglia (collateral ganglia) (lesser and least splanchnic)
– Postganglionic follow arteries in periarterial nerve plexus
Visceral afferent:
– Travel with sympathetic and parasympathetic neurons

Question 16

Sympathetic to head

Answer 16

cell bodies in lateral horn of upper thoracic spinal cord → preganglionic travel in ventral rootlets → ventral root → spinal nerve → anterior rami → white rami communicans → sympathetic chain ganglia (up) → synapses in superior cervical ganglion (top of sympathetic chain) → postganglionic runs out to the carotid plexus (NOT via gray rami communicans), runs via the common carotid to arteries going to target (or sometimes catches a ride on cranial nerves)

Question 17

Innervation of large intestine (P and S to L colic flexure)

Answer 17

Parasympathetic:
– Vagus (preganglionic) to terminal ganglia within intestinal wall
Sympathetic:
– Thoracic splanchnic (preganglionic) to superior mesenteric ganglia (lesser)
– Postganglionic follow arteries in oeriarterial nerve plexus

Question 18

Innervation of esophagus

Answer 18

Parasympathetic:
–Vagus (preganglionic) to terminal ganglia within wall
Sympathetic
– Visceral (splanchnic) branches of cervical and thoracic sympathetic trunks
Visceral afferent:
– Travel with sympathetic and parasympathetic neurons

Question 19

Innervation of stomach and spleen

Answer 19

Parasympathetic:
– Vagus nerves (preganglionic) to terminal ganglia within wall
Sympathetic:
– Thoracic splanchnic (greater) to celiac ganglion (collateral ganglia)
– Postganglionic follow arteries in periarterial nerve plexus
Visceral sensory:
– Travel with sympathetic and parasympathetic neurons

Question 20

Sympathetic to heart

Answer 20

cell bodies in lateral horn of upper thoracic spinal cord → preganglionic travel in ventral rootlets → ventral root → spinal nerve → anterior rami → white rami communicans → sympathetic chain ganglia (up) → synapses in cervical ganglia of the sympathetic chain → postganglionic go in visceral branches to the heart (NOT through gray rami communicans)