Cranial nerves

Question 1

General properties of cranial nerves

Answer 1

• Soft and squishy
• Carry many different types of fibres
• Pass through holes in hard bone
• They are easily compressed due to tumours, inflammation and fractures

Question 2

Which kind of fibres pass through cranial nerves

Answer 2

Motor fibres:

• Somatic
• Visceral

Sensory:

• Visceral
• General: from skin and mucous membranes
• Special: e.g. taste, vision, hearing..

Question 3

Olfactory nerve

Answer 3

• Cranial nerve 2
• Sensory nerve of smell
• Receptors in the epithelium of nasal cavity
• Pass through foraminifera pf the crib form plate
• Into Olfactory bulb of the anterior cranial fossa

Question 4

Optic nerve

Answer 4

Cranial nerve 3

• Comes in through optic canal to form optic chiasm
• Nasal optic fibres cross over to form the optic tract

Question 5

Clinical application to CNII

Answer 5

• Increase in pressure of CSF can cause Papilloedema
• damage to right optic nerve causes ipsilateral eye vision loss
• damage at optic chiasma causes loss of peripheral vision (bitemporal hemianopsia)
• Damage to right optic tract causes loss of ipsilateral nasal vision loss and contralateral peripheral/temporal vision loss (homonymous hemianopsia)

Question 6

Clinical application to CN I

Answer 6

Fractured crib form plate can cause olfactory fibres to become damaged causing anosmia

Question 7

Oculomotor nerve

Answer 7

Cranial nerve 3
-From midbrain through superior orbital fissure
-Visceral motor:
parasympathetic to pupil constricts pupil
parasympathetic to ciliary muscle accommodates lens
-Somatic motor
to superior, inferior and medial rectus
To the inferior oblique muscle

Question 8

clinical application to CN 3

Answer 8

• Drooping of eyelid
• Eyeball pointing outwards and down
• No accommodation of the lens
• No pupillary reflex

Question 9

Trochlear nerve anatomy and clinical appication

Answer 9

Cranial nerve 4

• From dorsal surface of the the midbrain through the superior oblique muscle
• somatic motor innervation to to the superior oblique muscle

-Diplopia when looking down

Question 10

Abducens nerve

anatomy and clinical application

Answer 10

cranial nerve 6

• From pons and medulla through the superior orbital fissure
• Somatic motor innervation to lateral oculomotor muscle

-Medial deviation of eye which leads to Diplopia

Question 11

Trigeminal nerve (ophthalmic )

Answer 11

CN V1

• From pons through to trigeminal ganglion to superior orbital fissure
• General sensory from the eyelid, scalp, mucosa of the nasal cavity and sinuses, forehead, cornea

Question 12

Trigeminal nerve maxillary

Answer 12

CN V2

• From pons through to trigeminal ganglion through to the foramen rotunda
• general sensory from the maxilla, maxillary teeth, TMJ, Maxillary sinuses and palate

Question 13

Trigeminal nerve mandibular

Answer 13

V3
From pons to trigeminal ganglion through to the foramen vale
-General sensory from the mandibular teeth, TMJ, Mucosa of the mouth, anterior 2/3rds of the tongue
-Somatic motor: muscles of mastication, digastric, tensor velar palatine and tensor tympani

Question 14

Clinical application of trigeminal mandibular

Answer 14

• Trigeminal neuralgia
• Loss of sensation to the face
• Loss of cornea/sneezing reflex
• Paralysis to muscles of mastication

Question 15

Facial nerve

anatomy

Answer 15

CN VII
From between the pons and the medulla it exits via the internal acoustic meatus, the facial canal and the stylomastoid foramen
motor somatic: to muscles of facial expression and scalp, stapedius and part of digastric
Visceral motor:to the submandibular, sublingual, lacrimal and nose and palate glands
Special sensory: anterior 2/3rd of tongue
General sensory: through external acoustic meatus

Question 16

Facial nerve clinical

Answer 16

• easily prone to damage due to long trajectory through bone

- Bell’s palsy

Question 17

Vestibulococchlear nerve anatomy

Answer 17

CN IX
-From pons and medulla 
-Through internal auditory meatus 
-Special sensory 
postion/balance via semicircular canals, utricle and saccule 
Hearing from cochlea

Question 18

Clinical vestibuloccochlear

Answer 18

• tinnitus
• vertigo
• nystagmus
• deafness

Question 19

Glossopharangeal nerve anatomy

Answer 19

Cranial nerve IX
-From medulla through jugular foramen
-Special sensory: posterior 1/3rd of tongue
-Visceral sensory:
carotid body and sinus
-General sensory: cutaneos middle ear and posterior mouth cavity
-Somatic motor : To stylopharangeus: helps with swallowing
-Visceral motor: Parasympathetic to parotid gland

Question 20

Glossopharangeal clinical

Answer 20

• Loss of gag reflex
• Loss of taste in back of mouth
• Associated with damage to cranial nerve X,XI

Question 21

Vagus nerve anatomy

Answer 21

Cranial Nerve

• From the medulla to the jugular foramen an then to everywhere
• Special sensory: auricle and external acoustic meatus
• general sensory: from auricle and palate
• Visceral sensory : GI from pharynx to SI, heart, bronchi, trachea
• Somatic motor: pharynx to oesophagus in GI and palate
• Visceral motor: Gut, bronchi and heart

Question 22

Vagus nerve clinical

Answer 22

Problems with pharyngeal branches lead to problems with swallowing

Problems with larangeal problems lead to problem with speaking

Question 23

Accessory nerve

Answer 23

Cranial nerve XI

• From cranial medulla and large spinal nerve roots through the jugular foramen
• Somatic motor innervation of the striated muscles of the soft palate, pharynx, larynx, sternocleidomastoid and trapezius

Clinical
-Difficulty turning head and shrugging shoulders

Question 24

Hypoglossal nerve

Answer 24

Cranial nerve XII

• From the medulla through the hypoglossal canal
• Somatic motor innervation of the muscles of the tongue

Clinical”:

• Damage associated with a. tonsillectomy
• Can lead to atrophy and paralysis of ipsilateral side of tongue.

Question 25

nerve supply of tongue?

Answer 25

General sensory to the anterior 2/3rd of the tongue: lingual nerve (branch of V3) General sensory to posterior 1/3rd: glossopharyngeal Special sensory to anterior 2/3rd: chorda timpani of VII Special sensory to posterior 1/3rd: CN IX