7. Cranial Nerves 3/ Cavities, Sensation and Secretion

Question 1

Function of trigeminal nerve?

Answer 1

Primary function:

• Sensation to the head and cavities (general somatic afferent)
• Motor to muscles of mastication (special visceral efferent)

Additional functions:

• Carrier of Autonomic Fibres
• Parasympathetic (general visceral efferent)
• Anterior 2/3 Taste/Gustation (special visceral afferent). Produced by CN VII but carried by CN V

Question 2

What is the function so CN VII and nervus intermedius?

Answer 2

Primary functions:
- Motor to Muscles of Facial Expression (special visceral efferent)

Additional functions:

• Parasympathetic (general visceral efferent)
• Anterior 2/3 Taste/Gustation (special visceral afferent). Sensation produced here.

Question 3

What are the nuclei used by the CN V?

Answer 3

General Somatic Afferent to the MESENCEPHALIC, CHIEF SENSORY & SPINAL nuclei in the midbrain, pons & medulla oblongata

Special Visceral Efferent from the MOTOR nucleus in the pons to the muscles of mastication (derived from 1st pharyngeal arch)

Question 4

CN V is the carrier for parasympathetic & taste fibres originating in the _______ ________component of CN VII

Answer 4

CN V is the carrier for parasympathetic & taste fibres originating in the nervus intermedius component of CN VII

Question 5

Where is the trigeminal ganglion found?

Answer 5

In Meckel’s cave (within dura mater) on the apex of the petrous temporal bone

Question 6

What are the nuclei and modalities of the CN VII?

Answer 6

Special Visceral Efferent from the MOTOR nucleus in the pons to the muscles of FACIAL EXPRESSION & a few additional muscles such as the stapedius, stylohyoid & posterior belly of digastric (all derived from 2nd pharyngeal arch)

Question 7

What are the nuclei and modalities of CN VII with Nervus Intermedius?

Answer 7

General Visceral Efferent (parasympathetic) from the SUPERIOR SALIVATORY NUCLEUS in the PONS to the lacrimal gland, nasal & oral cavities (mucous membranes), sinuses, submandibular & sublingual salivary glands

Special Visceral Afferent to the SOLITARY NUCLEUS in the MEDULLA OBLONGATA receiving TASTE from the anterior 2/3 of the tongue (via the chorda tympani nerve)

Question 8

What are the 4 PS ganglion of the head?

Answer 8

Ciliary: Fibres of the edinger-westphal nucleus assocatied with CN III
Pterygopalatine: Receives from CN VII
Submaxillary: Receives from CN VII
Otic: Receives from CN IX

Question 9

What is the geniculate ganglion?

Answer 9

The geniculate ganglion contains fibres for taste and somatic sensation and is located in the petrous temporal bone.

Fibres in:

• Facial nerve (labyrinthine segment)
• Nervus intermedius

Fibres out:

• Facial nerve (tympanic segment)
• Greater superficial petrosal nerve
• Lesser petrosal nerve
• External petrosal nerve

Question 10

What is the course of the greater petrosal nerve?

Answer 10

Branches from nervus intermedius of CN VII in the geniculate ganglion.

• -> Escapes from the middle ear and lies on the surface of the petrous temporal bone in the middle cranial fossa
• -> Passes through foramen lacerum
• -> Heads towards the pterygoid canal

Question 11

Function of the greater petrosal nerve?

Answer 11

Greater petrosal nerve, from the nervus intermedius of CN VII, carries:

1. General visceral efferent (PS secretomotor) fibres that contribute to the innervation of the LACRIMAL GLAND
2. Special visceral afferent (GUSTATION/TASTE) fibres from the palate

Question 12

Greater petrosal & deep petrosal nerves combine as the nerve of the ______ _______

Answer 12

Greater petrosal & deep petrosal nerves combine as the nerve of the pterygoid canal

Question 13

What gives off the deep petrosal nerve?

Answer 13

SYMPATHETIC PLEXUS on the internal carotid artery in the carotid canal

Question 14

Which two nerves are found int he pterygopalatine fossa?

Answer 14

Nerve of the pterygoid canal (combination of deep and greater petrosal nerve, passing through the pterygoid canal)

+

CN V2 (that has passed through the foramen rotundum)

Question 15

Position of the pterygopalatine fossa?

Answer 15

Pterygopalatine fossa lies just LATERAL to the upper aspect of the NASAL cavity & NASOPHARYNX behind the ORBIT & above the hard/soft PALATE

Question 16

What is the input and output at the pterygopalatine ganglion?

Answer 16

1. PREGANGLIONIC parasympathetic fibres from the nervus intermedius of CN VII (via the greater petrosal & nerve of pterygoid canal) synapse in the pterygopalatine ganglion
2. POSTGANGLIONIC fibres hitch-hike with branches of the CN V2 and some branches of CN V1.
   Output to:
   -Orbit (lacrimal gland)
   -Maxilla (sinus, palate, upper teeth and gums)
   -Nasal cavity
   -Nasopharynx

Question 17

All branches of CN ____ are also accompanied by branches of the maxillary artery

Answer 17

All branches of CN V2 are also accompanied by branches of the maxillary artery

Question 18

Where is the pterygopalatine ganglion found?

Answer 18

Pterygopalatine ganglion is within the pterygopalatine fossa

Question 19

What is the innervation fo the lacrimal gland?

Answer 19

1. Lacrimal nerve, a branch of CN V1

2. Zygomaticotemporal (from the zygomatic of CN V2 that joins the lacrimal nerve)

Question 20

What nerve supplies the frontal sinus?

Answer 20

The supraorbital nerve (branch of the frontal nerve from CN V1)

Question 21

What supplies the ethmoidal sinuses, lateral wall of nasal cavity & nasal septum?

Answer 21

Anterior ethmoidal nerve with posterior ethmoidal nerve behind it

Question 22

How do other nerves & vessels enter & leave the nasal cavity?
Cribiform plate, nares, incisive canal, sphenopalatine foramen, palatine canal

Answer 22

Cribriform plate: Olfactory nerves & anterior ethmoidal nerve

Nares: Branches of the facial artery and infraorbital nerve

Incisive canal: The nasopalatine nerve passes to the anterior aspect of the palate and terminal branches of the greater palatine atery enter the nasal cavity

Sphenopalatine foramen: Medial to the pterygopalatine fossa for the passage of artery (sphenopalatine) & branches of CN V2 (nasopalatine)

Palatine canal: Nasal branches of the greater palatine nerve with arteries pass from the palatine canal through small foramina

Question 23

What provides the lateral nervous supply to the nasal wall?

Answer 23

Anterior and superior:
From CN V1 via the anterior ethmoidal nerve

Posterior and inferior:
From CN V2 mainly via the greater palatine nerve

Question 24

Olfactory nerves are capable of ________!

Answer 24

Olfactory nerves are capable of regeneration!

Question 25

Shingles (herpes zoster) at the tip of the nose may herald corneal involvement. Why?

Answer 25

Anterior ethmoidal nerve continues as the external nasal nerve that supplies the tip of the nose.
Anterior ethmoidal is a branch of the nasociliary (CN V1) that supplies the cornea

Question 26

What is the nervous supply to the medial nasal wall and septum?

Answer 26

Anterior, superior:
From nasal nerves of CN V1

Posterior, inferior:
-From nasal nerves of CN V2 mainly via nasopalatine nerve

Question 27

What accompanies the CN V2 branches that supply the anterior and superior medial nasal wall?

Answer 27

CN V2 branches are accompanied by branches of the MAXILLARY branch of the EXTERNAL carotid artery

Question 28

What accompanies the CN V1 branches that supply the anterior and superior medial nasal wall?

Answer 28

CN V1 branches are accompanied by branches of the OPHTHALMIC branch of the INTERNAL carotid artery

Question 29

Innervation of the palate?

Answer 29

Hard and soft palate:
Greater & lesser palatine branches of CN V2 (plus secretomotor from the pterygopalatine ganglion) supply

Anterior palate:
Nasopalatine nerve

Question 30

The ___________ nerve (CN IX) supplies the tonsils & may encroach onto the soft palate (referred pain to middle ear)

Answer 30

The glossopharyngeal nerve (CN IX) supplies the tonsils & may encroach onto the soft palate (referred pain to middle ear)

Question 31

What supplies the sphenoidal sinuses?

Answer 31

CN V1 and V2

Question 32

What supplies the maxillary sinus

Answer 32

The INFRAORBITAL nerve along with the SUPERIOR ALVEOLAR nerves (anterior, middle & posterior) on their way to the teeth & gums

Question 33

Where does the chorda tympani (CN VII) nerve join the lingual nerve (CN V)?

Answer 33

In the infratemporal fossa

Question 34

What is the nervous supply of the lingual nerve (branch of CN V3)?

Answer 34

1. General somatic sensation
   from anterior 2/3 of tongue, floor of mouth mucosa & mandibular lingual gum
2. Carrier of general visceral efferent (parasympathetic secretomotor) to sublingual & submandibular glands
3. Carrier of special visceral afferent for taste of anterior 2/3 of tongue via chorda tympani nerve (CN VII nervus intermedius )

Question 35

The lingual nerve (CN V3) enters the oral cavity between which 2 muscles?

Answer 35

Mylohyoid and hyoglossus

Question 36

What is the innervation of the salivary glands?

Answer 36

Lingual nerve:

1. Preganglionic parasympathetic fibres leave the lingual nerve & synapse in the submandibular ganglion
2. Postganglionic branches pass to the submandibular & sublingual salivary glands

Question 37

Oral cavity innervation?

Answer 37

CN V3 dividing just below the foramen ovale into lingual & inferior alveolar (dental) nerves
The INFERIOR ALVEOLAR NERVE supplies the:
-Lower teeth emerging as mental nerve to skin of chin & lower lip (both skin & mucous membranes)
-Mylohyoid
-Anterior belly of digastric