Nerves of the H&N CN VII - XII

Question 1

What are the extracranial branches of the facial nerve

Answer 1

Temporal

Zygomatic

Buccal

Marginal Mandibular

Cervical

Question 2

Where does the facial nerve run through during its course and what is significant about this structure

Answer 2

It runs through the parotid gland substance

Significant as injury/pathology affecting the gland can compress on the facial nerve and cause muscle weakness

Question 3

What branches does the facial nerve give off while in the petrous bone

Answer 3

Greater petrosal nerve - purely parasympathetic. Innervates lacrimal glands, mucosal glands and glands in roof of oral cavity

Chorda tympani nerve - innervates anterior 2/3 tongue and carries parasympathetic fibres to submandibular and sublingeal glands

Nerve to stapedius - innervates stapedius. Stapedius dampens down excessive vibration of stapes bone at oval window

Question 4

Where does the facial nerve exit the skull

Answer 4

Facial nerve exits skull through stylomastoid foramen

Question 5

What are the functions of the facial nerve

Answer 5

Special sensory - detects taste in anterior 2/3 of tongue

Autonomic - parasympathetic innervation to lacrimal glands, mucosal glands, glands in roof of mouth and salivary glands (except parotid)

Motor - muscles of facial expression and stapedius

General sensory - small area of external ear

Question 6

How is the facial nerve tested

Answer 6

Testing muscles of facial expression

Testing corneal reflex

Question 7

Describe the path that the vestibulocochlear nerve runs from its origin to termination

Answer 7

Nerve originate from cochlea and semi-circular canals

Nerves in these areas come together to form the vestibulocochlear nerve

Nerve enters internal auditory meatus -> terminates at junction between pons and medulla

Question 8

What are the functions of the vestibulocochlear nerve

Answer 8

Hearing

Balance

Question 9

What do you do when testing vestibulocochlear nerve damage

Answer 9

Test hearing and enquire about balance - see if both or only one part affected

Question 10

What causes sensorineural

Answer 10

Sensorineural = hearing loss

Damage to the cochlea

Damage to cochlea component of vestibulocochlear nerve

Damage to brainstem nucleus

Question 11

What causes vertigo

Answer 11

Vertigo = disturbance of balance

Pathology involving semi-circular canals, vestibular component of vestibulocochlear nerve or brain nuclei

Question 12

What is presbyacusis

Answer 12

Presbyacusis - progressive, usually bilateral, sensorineural hearing loss that occurs in older people as they age

Question 13

Describe how the nerves from the medulla exit the skull

Answer 13

CN IX, X, XI all exit via jugular foramen with the IJV -> enter superior part of carotid sheath -> quickly exit sheath to travel to target tissue - except CN X which runs length of sheath

CN XII exits via hypoglossal canal

Question 14

What are the functions of the glossopharyngeal nerve

Answer 14

General sensation - palatine tonsils and oropharynx, middle ear and tympanic membrane, and sensory from carotid body and sinus

Special sensory - taste and general sensation of posterior 1/3 of tongue

Autonomic - PNS fibres to parotid gland

Motor - stylopharyngeus muscle (assists swallowing)

Question 15

Which branch of the glossopharyngeal nerve gives sensory innervation of the ear. What else does it carry

Answer 15

Tympanic branch

Also carries PNS fibres

Question 16

How can the glossopharyngeal nerve be tested

Answer 16

Gag reflex - also tests vagus nerve. Used with concerns around swallowing and integrity of nerves in the reflex

Taste no formally tested

Lesions of CN IX are unlikely

Question 17

What are the functions of the vagus nerve

Answer 17

General sensory - lower pharynx and larynx. Sensory to posterior part of external ear and tympanic membrane

Motor - muscles of soft palate, pharynx and larynx. Allows speech, swallowing and coughing

Autonomic - parasympathetic to thoracic and abdominal viscera

Question 18

What is the function of the spinal accessory nerve

Answer 18

Motor - SCM and trapezius

Question 19

How is CN XI tested

Answer 19

Test trapeqius using shoulder shrug against resistance

Test SCM by turning head against resistance

Question 20

Where can CN XI be easily damaged and why

Answer 20

CN XI can be easily damaged in posterior triangle as it runs quite superficial -> susceptible to injury

Question 21

What is the function of the hypoglossal nerve

Answer 21

Motor - muscles of the tongue (all but one). Allows tongue movement