Parasympathetic Nervous System

How do the cranial parasympathetic nerves exit the skull?

Via CNs III, VII, IX, X

Where is the parasympathetic preganglionic fiber of CN III located?

In edinger Westphall nucleus of CN III complex

How do the cranial parasympathetic nerves exit the skull?

Via CNs III, VII, IX, X

Where is the parasympathetic preganglionic fiber of CN III located?

In edinger Westphall nucleus of CN III complex

Parasympathetic fibers in right edinger westphall nucleus go to what eye=?

RIGHT (ipsalateral )

Path of preganglionic parasympathetic fiber from CN III

1. Cell body in edinger Westphal nucleus

2. Fibers follow CN III as it exits the midbrain @interpreduncular fossa, close to circle of Willis, and into the cavernous sinus

3. Jumps onto inferior oblique muscular branch of inferior CN III just before going through superior orbital fissure

4. Parasympathetic fibers leave the muscular branch right before it reaches the inferior oblique, now called "motor root"

5. Motor root Enters ciliary ganglion + synapses

Where do parasympathetic fibers run along CN III? What does this mean?

Run on outside of CN III

Compression of III will cause parasympathetic loss, with or without affecting GSE fibers

When is CN III palsy a medical emergency? Why?

If there is pupillary involvement (parasympathetic fibers are affected).

Potential intracranial aneurysm

Complete opthalmoplegia (what is it, what does it look like)?

CN III palsy with pupillary involvement

Eye is down and our, ptosis, mydriasis

Postganglionic parasympathetic fiber of CN III

1. Cell body in ciliary ganglion

2. Follows short ciliary nerves + runs in Suprachoroid space

3. Innervates iris sphincter + ciliary mucles

What does the longitudinal ciliary muscle fibers do?

Pulls ciliary body forward

What do the radial ciliary muscle fibers do?

Pulls ciliary body in

Where is the facial nuclei located?

Tegmentum of pons

What do the fibers from the facial motor nucleus innervate?

Muscles originating from 2nd branchial arch:

Muscles of facial expression

Stapedius

Posterior belly of digastric

What kind of fibers does the lacrimal nucleus have?

Preganglionic parasympathetic fibers

What kind of fibers does the superior salivatory nucleus have?

Preganglionic parasympathetic fibers (GVE)

SVA fibers (chorda tympani)

Where does CN VII exit the brain stem?

Pontomedullary junction

Lateral to CN VI and medial to CN VIII

How does CN VII exit the brain stem?

As two branches:

Motor root

Nervus intermedius

Motor root of CN VII has what fibers?

All fibers from facial motor nucleus (SVE)

Nervus Intermedius of CN VII has what fibers?

GSA

SVA

GVE

The GSA fibers of the Nervus Intermedius of CN VII innervate what?

Ear canal

The SVA fibers of Nervus Intermedius of CN VII innervate what?

Taste buds of body of tongue

The GVE fibers of Nervus Intermedius of CN VII innervate what?

Lacrimal gland

Submandibular + sublingual gland

The Nervus intermedius contains fibers from what CN VII nuclei?

lacrimal nucleus

Superior Salvatory

Superior Salivatory fibers of CN VII pathway

1. Nucleus in pons

2. Leaves pons as Nervus intermedius root @ pontomedullary junction

3. follows CN VII+ Enters internal acoustic meatus and runs in facial canal

4. Runs through geniculate ganglion without synapsing + reaches middle ear

5. Leaves 7 as chorda tympani in middle ear, passes through ear + leaves at floor

6. Enters area below tongue and into submandibular ganglion, where it synapses on postganglionic fibers

7. Postgnaglionic fibers leaves ganglion + innervates submandibular/lingual glands

Where is the submandibular ganglion located?

Submandibular triangle

Where is the submandibular triangle?

Medial to body of mandible + lateral to anterior and posterior belly of digastric

Lacrimal fibers of CN VII pathway

1. Nucleus in pons

2. Leaves pons as Nervus intermedius root @ pontomedullary junction

3. follows CN VII+ Enters internal acoustic meatus and runs in facial canal

4. Leaves CN VII as greater superficial Petrousal before it reaches geniculate ganglion

5. Joins deep Petrousal nerve to form vidian nerve

6. Vidian nerve enters pterygopalantine ganglion in pterygopalantine fossa.

7. Preganglionic fibers synapse in ganglion

8. Postganglionic fibers (+ sympathetic) join maxillary nerve in ganglion + go through infraorbital fissure onto infraorbital nerve

9. Jump onto zygomatic nerve and then onto lacrimal nerve + enters lacrimal gland (both parasympathetic and sympathetic)

What kind of ganglion is the geniculate ganglion?

Sensory ganglion

What kind of fibers make up the deep Petrousal nerve?

Postganglionic sympathetic fibers from the internal carotid

What fibers does the inferior Salvatory nucleus of CN IX have?

GVE (preganglionic parasympathetic fibers)

Pathway of CN IX parasympathetic fibers

1. Pregang cell bodies in inferior salivatory nucleus in medulla

2. Leave medulla on CN IX via posterolateral fissure

3. Exits skull by passing through jugular foramen

4. Parasympathetic fibers follow the tympanic branch of CN IX into petrous bone/floor of ear + into middle ear

5. Tympanic nerve forms promontory plexus on medial wall of middle ear

6. Lesser superficial Petrousal comes off of plexus + passes through anterior wall of petrous/ear

7. Passes through foramen ovale into infratemporal fossa + into otic ganglion where it synapses

8. Post ganglionic fibers jump of auriculotemporal n. Of V3 to parotid gland

Where are the CN X nuclei?

Medulla

What are the CN X nuclei?

Dorsal nucleus

Nucleus ambiguous

What fibers make up the dorsal nucleus of CN X?

100% preganglionic parasympathetic cell bdies

What fibers make up the nucleus ambiguous

Mostly SVE fibers with some preganglionic parasympathetic fibers

What do the fibers of the dorsal nucleus of CN X innervate?

Parasympathetic GVE to GI system before the splenic flexure

What do the parasympathetic fibers of the nucleus ambiguous of CN X innervate?

parasympathetic GVE to heart

Where does CN X exit medulla?

Posterolateral fissure

Where are the postganglionic cell bodies of CN X? Examples?

Located in walls of organs (x: meissner / Auerbachs plexus)

What ANS section does not have a central neuron?

Cranial parasympathetics

Where are the preganglionic sacral parasympathetic fibers

Interomedial lateral cell horn of S2-S4

Where are the postganglionic sacral parasympathetic fibers located?

Wall of organs

What do the sacral parasympathetic fibers innervate?

GI after splenic flexure (descending, sigmoid, rectum)

Smooth muscle of bladder

Smooth muscle in corpora cavernosum + spongiosum (erection)

Sacral parasympathetic preganglionic fibers are part of?

Cauda equina

What does complete damage to the cauda equina cause?

Flaccid paralysis

Loss of defecation + micturation

What does a spinal injury above cauda equina (above L1) cause?

Spastic paralysis

Loss of controls of defectation + micturition (work reflexively)

What can often cause damage to the parasympathetic fibers of CN III

Intercranial aneurysm @ circle of willis

32% of intercranial aneurysms occur where in the circle of Willis?

Posterior communication arteries

Basically tip

Which CNs do sensory to the ear canal?

CN V, VII, IX, X

What spinal nerves innervate the leg?

L1-S2

What spinal nerves innervate the anteromedial leg?

L1-L4

What spinal nerves innervate posterolateral leg?

L4-S2

When does CN VII have NO parasympathetic fibers on it

Once it exits the facial canal via stylomastoid foramen