Week 8 - Cranial nerves 3, 5 and 7

Question 1

Which structures pass through the cavernous sinus?

Answer 1

• CN III, IV, V1, V2 and VI

- ICA

Question 2

Where is the oculomotor nucleus?

Answer 2

-Midbrain

Question 3

What type of nerve is oculomotor nerve proper?

Answer 3

-Somatic efferent (motor)

Question 4

What is the function of oculomotor nerve proper?

Answer 4

-Innervates the extraocular muscles of the eye except lateral rectus, superior oblique and superior tarsal

Question 5

Why is oculumotor nerve said to have parasympathetic function?

Answer 5

-The edinger-westphal nucleus lies close to the oculomotor nucleus and the fibres ‘hi-jack’ the oculomotor nerve to get to their destinations

Question 6

Describe a palsy of oculomotor nerve proper

Answer 6

• Down and out pupil due to loss of extraocular muscles leaving unopposed action of LR and SO
• Ptosis

Question 7

In an oculomotor nerve lesion, what does it tell you if there is myadriasis?

Answer 7

-Lesion is proximal to the ciliary ganglion as there is also damage to the parasympathetic portion of oculomotor nerve due to loss of pupillae constrictor leading to unopposed pupillae dilator

Question 8

Name the branches of CNV

Answer 8

• Ophthalmic
• Maxillary
• Mandibular

Question 9

What type of nerve is CN V?

Answer 9

-Mixed -> sensory, motor

Question 10

Why is trigeminal nerve said to have sympathetic function?

Answer 10

-Hi jacked by sympathetic fibres from the superior cervical ganglion

Question 11

Does CNV carry parasympathtic innervation?

Answer 11

-No, the ganglion of the parasympathetic fibres lay in the distribution of the trigeminal nerve

Question 12

What is the function of CNV1?

Answer 12

• Ophthalmic branch of CNV

- Sensory innervation to the forehead, upper lid, brow, and bridge of nose, cornea, conjunctiva

Question 13

Through which foramen in the cranial cavity does CNV1 pass?

Answer 13

-Superior orbital fissure

Question 14

What sympathetic innervation hijacks CNV?

Answer 14

• Sweating

- Vasomotor

Question 15

What is the function of CNV2?

Answer 15

-Sensory innervation to lower lid, cheeks, nares, nasal cavity, upper lip/teeth

Question 16

Through which foramen in cranial cavity does CNV2 pass?

Answer 16

-Foramen rotundum

Question 17

What is the function of CNV3?

Answer 17

• Sensory to lower lip/teeth, jaw

- Motor to MoM

Question 18

Through which foramen in the cranial cavity does CNv3 leave?

Answer 18

-Foramen ovale

Question 19

What type of nerve is CNVII?

Answer 19

-Mixed (special sensory, general sensory, parasymp and motor)

Question 20

What are the functions of CNVII?

Answer 20

• Special sensory -> ant 2/3 tongue
• General sensory -> auricles of ear
• Motor -> Muscles of facial expression
• Parasymp -> Lacrimation and salivation (submandib and subling), nasal and palatine glands

Question 21

Which branch of facial nerve do the parasympathetic fibres hijack?

Answer 21

-Greater pertrosal nerve

Question 22

Describe the route of facial nerve

Answer 22

-Traverse the posterior cranial fossa, exits via internal auditory meatus, facial canal, stylomastoid foramen, parotid gland -> splits into 5 extracranial branches

Question 23

Name the extracranial branches of facial nerve

Answer 23

• Temporal
• Zygomatic
• Buccal
• Mandibular
• Cervical

Question 24

Which branches of facial nerve arise intracranially?

Answer 24

• Chorda tympani
• Nerve to stapedius
• Greater petrosal

Question 25

Which muscles of facial expression do which functions?

Answer 25

• Occipitofrontalis -> raise eyebrows
• Oblicularis oculi -> closes eyes
• Orbicularis oris -> Closes mouth and puckers lips
• Zygomaticus major-> smile
• Zygomaticus minor -> sad lips
• Buccinator -> draws cheeks to teeth

Question 26

Through which foramen in the cranial cavity does oculomotor nerve pass?

Answer 26

-Superior orbital fissure