Cranial Nerves Anatomy

Question 1

Which nerve innervates the tensor tympani muscle?

Answer 1

Trigeminal nerve (CN V)

Question 2

What are the 3 branches of the trigeminal nerve?

Answer 2

• Ophthalmic nerve (sensory only)
• Maxillary nerve (sensory only)
• Mandibular nerve (sensory and motor)

Question 3

How does the Ophthalmic branch of the trigeminal nerve exit the skull and what sensory function does it provide?

Answer 3

Exits skull via the Superior orbital fissure

Sensation:
- Scalp - Forehead - Upper eyelid
- Cornea - Nose - Nasal mucosa
- Frontal sinuses

Question 4

How does the maxillary nerve (trigeminal V2) exit the skull and what are its sensory innervations?

Answer 4

Exits the skull via Foramen Rotundum

Sensory:
- lower eyelid - cheek - upper lip
- upper teeth and gums - palate
- maxillary, ethmoid and sphenoid sinuses

Question 5

Through which foramen does the mandibular nerve (trigeminal V3) exit the skull through?

Answer 5

Foramen ovale

Question 6

What are the 4 muscles of mastication innervated by the mandibular nerve (trigeminal V3)?

Answer 6

• Masseter
• Temporalis
• Medial pterygoid
• Lateral pterygoid

Question 7

What are the 4 muscles other than the muscles of mastication, that are innervated by the mandibular nerve (V3)?

Answer 7

• Tensor veli palatini
• Mylohyoid
• Anterior belly of digastric
• Tensor tympani

Question 8

What is the motor and sensory origin of the facial nerve and where do they combine to make the facial nerve?

Answer 8

Motor: Pons
Sensory: Nervus intermedius

They pass through the petrous temporal bone into the Internal Auditory Meatus with the vestibulocochlear nerve. Here they combine to form the facial nerve

Question 9

What 3 branches arise in the facial canal and what is the relation of the facial canal path?

Answer 9

The canal passes superior to the vestibule of the inner ear.

3 branches that arise:
- great petrosal nerve: lacrimal glands (tears)
- nerve to Stapedius
- Chorda tympani: taste sensation to anterior 2/3 of tongue

Question 10

What two branches of the facial nerve arise as it passes through the stylomastoid Foramen?

Answer 10

• Posterior auricular nerve
• Branch to posterior belly of digastric and stylohyoid muscle

Question 11

What are the 5 main branches of the facial nerve and when does it divide into these branches?

Answer 11

Divides after entering the Parotid Gland.

• Temporal branch
• Zygomatic branch
• Buccal branch
• Marginal mandibular branch
• Cervical branch

Question 12

What nerve gives rise to taste and general sensation of the posterior third of the tongue?

Answer 12

Glossopharyngeal nerve

Question 13

Which nerve supplies sensation to the anterior 2/3 of the tongue?

Answer 13

Lingual branch of the mandibular division of the Trigeminal nerve (CN5)

Question 14

What facial muscles are supplied by the buccal branch of the facial nerve (CN7)?

Answer 14

• Zygomaticus minor: elevates upper lip
• Buccinator: Pulls corner of mouth and compresses cheek
• Levator anguli oris: pulls angle of mouth upward
• Orbicularis: closes and tightens lip
• Nasalis: Flares and compresses nostrils

Question 15

What is the motor innervation of all the extrinsic and intrinsic muscles of the tongue and what is the exception to this?

Answer 15

Hypoglossal nerve

Only the Palatoglossus is not innervated by the hypoglossal nerve. This is innervated by CN X

Question 16

Which nerve innervates the middle ear and what is the clinical significance of this?

Answer 16

Glossopharyngeal nerve

Pain may radiate to the middle ear following a tonsillectomy

Question 17

Which cranial nerve is most likely to be first affected by raised intracranial pressure?

Answer 17

Abducens nerve (CN6)