SM_20b: Autonomic Innervation of the Head and Neck

Question 1

In general, sympathetics are distributed to ____, while parasympathetics are restricted to ____, ____, and ____

Answer 1

In general, sympathetics are distributed to all vascularized portions of the body and sweat glands, while parasympathetics are restricted to head, neck, and body cavities

(glandular secretion, except for sweat glands, is parasympathetically mediated)

Question 2

Sympathetic fibers go to ____ and ____ in the eye

Answer 2

Sympathetic fibers go to dilator pupillae (opening pupil) and superior tarsal (raising eyelid) muscles in the eye

(sympathetic fibers go to vascular smooth muscle, sweat glands, and arrector pili muscles)

Question 3

Parasympathetic secretomotor neurons innervate ____ in the head, three pairs of large ____, the ____, and the ____ and ____ smooth muscles

Answer 3

Parasympathetic secretomotor neurons innervate mucosal glands in the head, three pairs of large salivary glands, the lacrimal gland, and the sphincter pupillae and ciliary muscle smooth muscles

Question 4

Target organs in the head and neck are responsible for ____, ____, and ____

Answer 4

Target organs in the head and neck are responsible for mucus flow, salivating, and crying

Question 5

Sympathetics ___ the pupil and ___ the eyelid, while parasympathetics ___ the pupil and ___ the lens

Answer 5

Sympathetics dilate the pupil (dilator pupillae) and raise the eyelid (superior tarsal muscle), while parasympathetics close down the pupil (sphincter pupillae) and accomodate the lens (ciliary muscle)

Question 6

In salivary and lacrimal glands, sympathetics produce more ____ secretions, while parasympathetics produce more ____ secretions

Answer 6

In salivary and lacrimal glands, sympathetics produce more viscous secretions, while parasympathetics produce more water secretions

Question 7

In mucosal glands, sympathetics produce more ____ mucus, while parasympathetics produce more ____ mucus

Answer 7

In mucosal glands, sympathetics produce more fluid mucus, while parasympathetics produce more viscous mucus

Question 8

Describe the three organizing principles of autonomic innervation to the head and neck

Answer 8

Three organizing principles of autonomic innervation to the head and neck

• Sympathetics in the head are postganglionic, traveling with branches of the carotid arteries
• Parasympathetic preganglionics leave the brain with CN III, VII, IX, and X and synapse in the ciliary (CN III), otic (CN IX), pterygopalatine (CN VII), and submandibular ganglia (CN VII) associated with trigeminal nerve branches
• Postganglionic parasympathetics are delivered to target organs by hitchhiking on sensory branches of CN V

Question 9

All sympathetics in the head are ____, traveling with branches of the ____ and ____ arteries

Answer 9

All sympathetics in the head are postganglionic, traveling with branches of the carotid (internal and external) and vertebral arteries

(preganglionic fibers synapse in the superior cervical ganglion)

Question 10

Postganglionic sympathetics regulate ____, ____, ____, and ____

Answer 10

Postganglionic sympathetics regulate blood flow (facial vessels), sweating, eyelid elevation (via superior tarsal muscle), and pupil dilation (via dilator pupillae muscle)

Question 11

Horner’s syndrome is interruption of the ____ due to a compression lesion of the ____

Answer 11

Horner’s syndrome is interruption of the postganglionic sympathetics due to a compression lesion of the sympathetic trunk

(at T1 outflow level due to a lung tumor in the mediastinum here)

Question 12

Parasympathetic preganglionics leave the brain with CNs ___, ___, ___, and ___ and synapse in four ganglia: ___, ___, ___, and ___ associated with trigeminal nerve branches

Answer 12

Parasympathetic preganglionics leave the brain with CNs III, VII, IX, and X and synapse in four ganglia: ciliary (CN III), otic (CN IX), pterygopalatine (CN VII), and submandibular (CN VII) associated with trigeminal nerve branches

COPS-3977: Ciliary 3, otic 9, pterygopalatine 7, submandibular 7

Question 13

Parasympathetic preganglionics synapse in four ganglia associated with ____ nerve branches

Answer 13

Parasympathetic preganglionics synapse in four ganglia associated with trigeminal nerve branches

Question 14

Trigeminal nerve is mostly ____ but includes ____ and ____

Answer 14

Trigeminal nerve is mostly general sensory but includes parasympathetic ganglia and target organs

(hitchhiking / overlay principle regarding parasympathetics and CN V branches: trigeminal network remains if you take away the autonomic fibers)

Question 15

Describe the ciliary ganglion

Answer 15

Ciliary ganglion

• Preganglionic parasympathetics fibers leave brain in CN III -> enter ciliary ganglion -> synapse
• Postganglionic fibers delivered to target organs with nasociliary (part of V1) branches known as short ciliary nerves (also contain sympathetics)
• Targets: sphincter pupillae, cilary muscle
• Lacrimal gland does NOT receive its parasympathetic innervation from CN III

Question 16

Parasympathetics supply two smooth muscles in eyeball: ____ and ____

Answer 16

Parasympathetics supply two smooth muscles in eyeball: sphincter pupillae and ciliary muscle

Question 17

Describe the otic ganglion

Answer 17

Otic ganglion

• Presynaptic parasympathetic fibers leave brain in CN IX -> exit jugular foramen -> tympanic branch re-enters skull and contributes to tympanic plexus in middle ear cavity -> fibers leave via lesser petrosal nerve -> out foramen ovale -> synapse in otic ganglion
• Postganglionic fibers delivered to target organ (parotid gland) with auriculotemporal nerve (V3)
• These secretomotor fibers regulate secretion of the parotid salivary gland

Question 18

_____ branch of the mandibular division of the trigeminal nerve (V3) splits around the middle meningeal artery, delivering postganglionic fibers to the _____

Answer 18

Auriculotemporal nerve branch of the mandibular division of the trigeminal nerve (V3) splits around the middle meningeal artery, delivering postganglionic fibers to the parotid gland

Question 19

Frey’s syndrome / gustatory sweating is ____ after ____

Answer 19

Frey’s syndrome / gustatory sweating is when sweat glands become activated and cheek becomes flushed and wet when salivation is stimulated after damaged postganglionic parasympathetic secretomotor fibers to parotid tissues undergo abnormal regeneration and incorrectly resupply the sympathetic innervated sweat glands and vessels of overlying skin

Question 20

Parasympathetics and sympathetics supply ____ target structures in the same general region

Answer 20

Parasympathetics and sympathetics supply different target structures in the same general region

(conflation of typically distinct functions / targets due to atypical nerve regeneration / connections and the unique use of ACh for both neurons in sweat glands)

Question 21

Describe the pterygopalatine ganglion

Answer 21

Pterygopalatine ganglion

• Preganglionic parasympathetic fibers leave brain in CN VII -> leave via greater petrosal nerve -> courses across foraemn lacerum -> joins deep petrosal sympathetic nerve and enters pterygoid canal -> goes into pterygopalatine fossa to synapse in ganglion
• Postganglionic fibers are distributed to target organs in midface and orbit: nasal mucosal glands via V2 branches, lacrimal gland via zygomatic (V2) to lacrimal (V1) nerves
• Secretomotor fibers regulate secretion of mucus and tears from the mucosal and lacrimal glands

Question 22

_____ joins with the _____ to form the nerve of the pterygoid canal

Answer 22

Sympathetic deep petrosal nerve joins with the parasympathetic greater petrosal nerve to form the nerve of the pterygoid canal

Question 23

Describe the bony pathway for the greater petrosal route

Answer 23

Bony pathway for the greater petrosal route

1. Internal acoustic meatus
2. Groove for greater petrosal
3. Goes across foramen lacerum
4. To enter pterygoid canal

Question 24

Pterygoid canal traverses the sphenoid at ____ from the ____ to ____

Answer 24

Pterygoid canal traverses the sphenoid at the base of the pterygoid plates from the foramen lacerum to the pterygopalatine fossa

(foramen rotundum runs parallel and above)

Question 25

Facial nerve (VII) branches in the ____

Answer 25

Facial nerve (VII) branches in the petrous temporal bone

Question 26

Describe the submandibular ganglion

Answer 26

Submandibular ganglion

• Presynaptic parasympathetic fibers leave brain in CN VII -> fibers leave via chorda tympani -> courses through infratemporal fossa and joins lingual nerve -> fibers synapse in submandibular ganglion
• Postganglionic parasympathetic fibers re-enter the lingual nerve (V3 branch to be distributed to the submandibular and sublingual glands
• These secretomotor fibers regulate secretion of the saliva from submandibular and sublingual and small salivary glands and mucous glands

Question 27

Parasympathetics to the submandibular / sublingual salivary glands include ____, ____, and ____

Answer 27

Parasympathetics to the submandibular / sublingual salivary glands include chorda tympani, lingual nerve, and submandibular ganglion

Question 28

Three branches of the facial nerve (CN VII) are ____, ____, and ____

Answer 28

Three branches of the facial nerve (CN VII) are greater petrosal, chorda tympani, and facial nerve proper

• Greater petrosal: joins deep petrosal to form nerve of the pterygoid canal
• Chorda tympani: joins lingual nerve
• Facial nerve proper: exits stylomastoid foramen

Question 29

Describe the parasympathetic pathway of oculomotor nerve (III)

Answer 29

Parasympathetic pathway of oculomotor nerve (III)

1. Oculomotor nerve (III)
2. Ciliary ganglion
3. Short ciliary nerves (V1 branches)
4. Sphincter pupillae and ciliary muscle

Question 30

Describe the parasympathetic pathway of glossopharyngeal nerve (IX)

Answer 30

Parasympathetic pathway of glossopharyngeal nerve (IX)

1. Glossopharyngeal nerve (IX)
2. Tympanic nerve, tympanic plexus
3. Lesser petrosal nerve
4. Otic ganglion
5. Auriculotemporal nerve (V3 branch)
6. Parotid gland

Question 31

Describe the parasympathetic pathway of facial nerve (VII)

Answer 31

Parasympathetic pathway of facial nerve (VII)

1. Facial nerve (VII)
2. Greater petrosal nerve
3. Nerve of pterygoid canal
4. Pterygopalatine ganglion
5. Maxillary nerve (V2 branches)
6. Nasal, palatal mucous glands and lacrimal gland

Question 32

Describe the parasympathetic pathway of facial nerve (VII)

Answer 32

Parasympathetic pathway of facial nerve (VII)

1. Facial nerve (VII)
2. Chorda tympani
3. Lingual nerve (V3 branch)
4. Submandibular ganglion
5. Lingual nerve
6. Submandibular and sublingual glands