Autonomics of the Head and Neck

Question 1

Which cranial nerves does the CRANIAL portion of the parasympathetic system leave the brainstem as?

Answer 1

Within CN III, VII, IX, and X (but vagus doesn’t do anything in head)

Question 2

What are the 4 parasympathetic ganglia within the head, and the parasympathetic fibers of which cranial nerves innervate them?

Answer 2

Ciliary (oculomotor)
Pterygopalatine (facial)
Submandibular (facial)
Otic (glossopharyngeal)

Question 3

What are the 3 roots of the ciliary ganglion, and what is connected through those roots?

Answer 3

The sensory root - connects the ganglion to the nasociliary nerve (branch of V1)
Sympathetic root - conveys postganglionic sympathetic fibers from the internal carotid plexus
Parasympathetic root - contains preganglionic parasympathetic fibers from oculomotor nerve and which synapse in the ganglion

Question 4

From the ciliary ganglion, where do the postganglionic parasympathetic fibers go and where do the postganglionic sympathetic fibers go?

Answer 4

Parasympathetic fibers go to
-ciliary muscle
-sphincter of the pupil
Sympathetic fibers go to
-dilator of the pupil
-vasculature of the eye

Question 5

Where does the pterygopalatine ganglion receive its preganglionic parasympathetic fibers? What 2 types of nerve fibers make up this particular fiber?

Answer 5

It receives them from the nerve of the pterygoid canal
The nerve of the pterygoid canal is a mix of
-preganglionic parasympathetic fibers and taste fibers from the greater petrosal nerve of the facial nerve
-postganglionic sympathetic fibers from deep petrosal nerve from the internal carotid plexus

Question 6

Which fibers are joined by the postganglionic parasympathetic fibers of the pterygopalatine ganglion?

Answer 6

• Greater and Lesser palatine nerves
• Posterior nasal branches
• Nasopalatine nerve
• Pharyngeal nerve
• Orbital branches
• Zygomatic nerve (which ultimately passes them off to lacrimal nerve of V1)
• superior alveolar nerve

Question 7

What are all the types of fibers that are contained in the greater and lesser palatine branches? What is the origin of each of these branches?

Answer 7

General sensory fibers from the maxillary division of the trigeminal
Parasympathetic fibers from the greater petrosal nerve (from CN VII)
Sympathetic fibers from the deep petrosal nerve (internal carotid plexus)
Taste fibers from the greater petrosal nerve (from CN VII)

Question 8

What nerve is actually attached to the submandibular ganglion?

Answer 8

lingual nerve of the V3 mandibular division trigeminal

Question 9

Where do the preganglionic parasymapthetic fibers and taste fibers that travel in the lingual nerve (of V3) originate from? Where do these fibers supply?

Answer 9

The preganglionic parasymapthetic fibers and the taste fibers originate in the chorda tympani of the facial nerve (CN VII)
Supplies the anterior 2/3 of the tongue

Question 10

Describe the course of the chorda tympani before reaching the submandibular ganglion via the lingual nerve of V3.

Answer 10

Chorda tympani leaves facial nerve in the petrous part of the temporal bone
Traverses the middle ear cavity
Leaves the skull through the petrotympanic fissure
Then synapse in the submandibular ganglion

Question 11

What are the 3 main structures that postganglionic parasympathetic fibers target after leaving the submandibular ganglion?

Answer 11

Submandibular gland

The rest join the lingual nerve and proceed to the sublingual and lingual salivary glands

Question 12

Where is the otic ganglion, and where does it receive its preganglionic fibers through (which nerve)?

Answer 12

It is located medial to the mandibular branch of the trigeminal
Outside of the foramen ovale
Deep in the infratemporal fossa

Receives its fibers from the lesser petrosal nerve

Question 13

What cranial nerve gives off the lesser petrosal nerve, and what is its course?

Answer 13

Glossopharyngeal nerve (CN IX) gives off the lesser petrosal.

1. Glossopharyngeal gives off the tympanic branch that enters middle ear cavity and contributes to the tympanic plexus
2. Tympanic plexus is the mixture of fibers from the tympanic branch of IX, the internal carotid plexus (sympathetic fibers) and a twig from the facial nerve
3. The parasympathetic fibers from the tympanic plexus leave as the lesser petrosal nerve
4. Lesser petrosal leaves petrous part of temporal and enters middle cranial fossa via hiatus of the lesser petrosal (runs lateral and parallel to the greater petrosal)
5. Lesser petrosal exists the skull through foramen ovale and enters infratemporal fossa
6. Synapses in otic ganglion
7. Postganglionic parasympathetic fibers are then passed to the aucriculotemporal nerve (V3) which distributions them to the parotid gland

Question 14

Where do the sympathetics that innervate the head and neck originate from? Both the preganglionic and ganglion.

Answer 14

The preganglionic fibers originate from the upper thoracic segments of the spinal cords in the lateral gray horns (interomedial gray columns)
The preganglionic fibers that are destined for the head synapse in the superior cervical ganglion

Question 15

Along which 2 arteries does the superior cervical ganglion send its fibers?

Answer 15

Along the internal and external carotid arteries (internal and external carotid nerves)

Question 16

What are the 2 plexi that are given off by the external carotid nerve from the superior cervical ganglion?

Answer 16

The external carotid nerve gives rise to the external carotid plexus as well as a smaller plexus along the common carotid (common carotid plexus)

Question 17

What are a few examples of areas supplied by the external carotid plexus?

Answer 17

Sweat glands of the face and neck
Salivary glands

Any area supplied by the external carotid artery is also supplied by the external carotid plexus and its sympathetic fibers

Question 18

What is the largest branch from the superior cervical ganglion to the head? What does it form on the internal carotid artery?

Answer 18

Internal carotid nerve is the largest

Forms a plexus on the internal carotid artery known as the internal carotid plexus

Question 19

What plexus receives some of the fibers from the internal carotid plexus when it is close to the middle ear cavity?

Answer 19

The tympanic plexus on the medial wall of the tympanic cavity

Question 20

What are the 2 main groups of sympathetic fibers given off by the internal carotid plexus as it travels along with the internal carotid artery? Where do those fibers go?

Answer 20

1. Sympathetic root of the ciliary ganglion
   - passes through the ciliary ganglion without synapsing
   - These fibers enter short ciliary nerves and are distributed to the dilator of the pupil and to the vasculature of the eye
2. Deep petrosal nerve
   - joins with the greater petrosal nerve of CN VII (facial) to form the nerve of the pterygoid canal
   - passes through the pterygopalatine ganglion without synapsing and are distributed to all branches of the maxillary division of trigeminal (V2)

Question 21

What are 4 outcomes of stimulation of sympathetic fibers in the head and neck area?

Answer 21

Dilation of the pupil (mydriasis)
Elevation of the eyelid (smooth muscle component of levator palpebrae superioris)
Vasoconstriction of the blood vessels of the head and neck
Sweating of the skin on face and neck

Question 22

What causes Horner’s syndrome? What are the symptoms?

Answer 22

Interruption of the sympathetic pathway in the head and neck
Symptoms include:
-ptosis (drooping of eyelid due to paralysis of smooth muscle component of levator palpebrae superioris)
-myosis (constriction of pupil)
-anhydrosis (no sweating in face and neck)
-vasodilation (redness in face and neck)
-enophthalmus (receding of eye into orbital cavity due to paralysis of the orbitalis muscle