Autonomic Nervous System Of The Head And Neck

Question 1

Where are the preganglionic sympathetic neurons located?

Answer 1

Thoracolumbar (T1-L2)

Question 2

True or False. There are preganglionic sympathetic fibers in the head.

Answer 2

FALSE

Question 3

Where are the preganglionic sympathetic cell bodies located?

Answer 3

Intermediolateral Cell column of the 1st and 2nd thoracic levels of the spinal cord

Question 4

Where do the postganglionic sympathetic fibers originate from?

Answer 4

Cervical Sympathetic Ganglia

Question 5

Describe the location of the Sympathetic Trunk or chain.

Answer 5

POSTerior to the Common Carotid and ANTerior to the Longus Colli and Capitus Muscles

* Usually embedded in OR deep to the prevertebral fascia

Question 6

Where does the Superior Cervical Ganglion receive preganglionics from? Where does it send its postganglionic fibers?

Answer 6

Preganglionics: Many from T1

Postganglionics: Upper Cervical (C1-3) and lower cranial nerves (IX-XII), the pharynx, Carotid body and sinus, and the internal carotid nerve

Question 7

Which nerve will form the internal Carotid Plexus? Where in the blood vessel will this be located?

Answer 7

Internal Carotid Nerve leaves the superior cervical ganglion and forms the internal carotid plexus in the TUNICA ADVENTITIA of the internal carotid

Question 8

The Internal Carotid Plexus is going to branch at which point?

Answer 8

Carotid Siphon

Question 9

List the 4 main branches off the Internal Carotid Plexus.

Answer 9

1. Perivascular Plexuses
2. Sympathetic Branch to the Ciliary Ganglion
3. Deep Petrosal Nerve
4. Carotico-tympanic Nerve

Question 10

Which structure controls the preganglionic fibers of the sympathetic nervous system in the neck?

Answer 10

HYPOTHALAMUS

Question 11

At which vertebral level is the middle cervical ganglion located? Where does it send its postganglionic fibers to?

Answer 11

C6

Middle Cervical Nerves (C4-6), and the Vertebral Artery via the Vertebral Plexus

Question 12

At which vertebral level is the Vertebral Ganglion located? Where does it send its postganglionic fibers to?

Answer 12

C7

C6 Nerve and the vertebral plexus

Question 13

What is the ansa subclavia?

Answer 13

Vertebral Ganglion sends a cord which will loop around the anterior surface of the subclavian artery and terminates in the Inferior Cervical (Stellate Ganglion)

Question 14

Describe the Stellate Ganglion. Where does it get preganglionics from? Where does it send postganglionics?

Answer 14

Fusion of the Inferior Cervical and the First Thoracic Ganglia.

It receives preganglionic fibers DIRECTLY from T1

Sends Postganglionic fibers to the Lower Cervical and First thoracic Nerves, heart, and vertebral and subclavian plexuses.

Question 15

What are the main causes of Horner’s Syndrome?

Answer 15

** Interruption of Sympathetic Innervation to the Head

1. Interruption of the cervical sympathetic trunk
2. Transection of the spinal cord above the level of T1
3. Hemisection of the spinal cord above the level of T1 (Brown-Sequard Syndrome)

Question 16

List the signs and symptoms of Horner’s Syndrome.

Answer 16

PAM is HORNY! (Ptosis, Anhidrosis, Mitosis)

• Slight ptosis (drooping) of the upper lid due to paralysis of the tarsal muscle
• Mitosis (pupillary constriction) due to paralysis of the dilator pupillae muscle
• Anhidrosis (inability to sweat normally) and blushing (vasodilation) of the skin on the face due to the loss of sympathetic innervation of the blood vessels.
• Enophthalmos (posterior displacement of the eyeball) due to paralysis of the orbitalis muscle of Müller which has a slight protrusion function
• The effects of Horner’s syndrome are usually TRANSIENT.

Question 17

Explain the route of the Sympathetic Branch to the Ciliary Ganglion off of the Internal Carotid Plexus.

Which muscles in the eye are innervated by sympathetics?

Answer 17

This small branch passes through the cavernous sinus, superior orbital fissure, and the CILIARY GANGLION before terminating as SHORT CILIARY nerves to the eyeball. These postganglionic sympathetic fibers innervate the DILATOR PUPILLAE and TARSAL muscles.

Question 18

Explain the route of the Deep Petrosal Nerve which is a Branch off of the Internal Carotid Plexus.

Answer 18

In the carotid canal, the deep petrosal nerve joins with the GREATER PETROSAL nerve to form the VIDIAN nerve. Postganglionic sympathetic fibers distribute to the palate, nasal cavity, pharynx, orbit and lacrimal gland.

Question 19

Explain the route of the Carotico-tympanic Nerve which is a Branch off of the Internal Carotid Plexus.

Answer 19

The caroticotympanic nerve enters the MIDDLE ear cavity, forms part of the tympanic plexus, and exits as the LESSER PETROSAL nerve. The postganglionic sympathetic fibers will course through the lesser petrosal nerve, foramen ovale, otic ganglion, and auriculotemporal nerve. It supplies postganglionic fibers to the PAROTID GLAND.

Question 20

What are the 4 Parasympathetic Ganglia that are associated with the head? Which cranial nerves are going to synapse in them? Where are the postganglionic fibers headed?

Answer 20

Question 21

List the Preganglionic Fibers to all four ganglia in the Head.

Answer 21

1. EDINGER-WESTPHAL NUCLEUS sends preganglionic fibers to the ciliary ganglion.
2. SUPERIOR SALIVATORY NUCLEUS sends preganglionic fibers to the sphenopalatine (pterygopalatine) and submandibular ganglia.
3. INFERIOR SALIVATORY NUCLEUS sends preganglionic fibers to the otic ganglion
4. DORSAL MOTOR NUCLEUS of X sends long, preganglionic parasympathetic fibers to scattered ganglia in the pharynx, larynx, thorax, and abdomen

Question 22

Describe the Autonomic Innervation of the Submandibular/Sublingual Glands.

Answer 22

Question 23

Describe the Autonomic Innervation to the Parotid Gland.

Where does the Internal carotid Plexus branch?

Answer 23

Postganglionic sympathetic neurons are clustered in the superior cervical ganglion. It receives preganglionic fibers mainly from T1. Postganglionic fibers from the SCG coalesce as the INTERNAL CAROTID NERVE, which forms the internal carotid plexus in the tunica adventitia of the internal carotid artery. The plexus follows the internal carotid artery into the skull and branches at the level of the CAROTID SIPHON.

The CAROTICO-TYMPANIC NERVE is a branch of the internal carotid plexus. The caroticotympanic nerve enters the middle ear cavity, forms part of the tympanic plexus, and exits as the LESSER PETROSAL NERVE. The postganglionic sympathetic fibers will course through the lesser petrosal nerve, foramen ovale, otic ganglion, and auriculotemporal nerve. It supplies postganglionic fibers to the parotid gland.

Question 24

Describe the Innervation to the Lacrimal Gland.

Answer 24

Question 25

Describe the Innervation to the Eye.

Answer 25