CN5 Trigeminal nerve

Question 1

What is cranial nerve 5?

Answer 1

Trigeminal nerve

Question 2

What is the route of the CN5 trigeminal nerve from its origin to its innervation?

Answer 2

Trigeminal ganglion lateral to cavernous sinus

divides into branches

Question 3

How many branches of the CN5 trigeminal nerve are there?

Answer 3

Three

Question 4

What are the branches of the CN5 trigeminal nerve?

Answer 4

Opthalmic

Maxillary

Mandibular

Question 5

What is the route of the opthalmic division of the CN5 trigeminal nerve from its origin to its innervation?

Answer 5

Passes through cavernous sinus
through superior orbital fissure
into orbit

Question 6

What is the route of the maxillary division of the CN5 trigeminal nerve from its origin to its innervation?

Answer 6

Passes through cavernous sinus
through foramen rotundum
into the pterygopalatine fossa

Question 7

What is the route of the mandibular division of the CN5 trigeminal nerve from its origin to its innervation?

Answer 7

Passes through foramen ovale

into the infratemporal fossa

Question 8

What are the functions of the CN5 trigeminal nerve?

Answer 8

General sensory - opthalmic, maxillary and mandibular branches supply corresponding regions of face

Motor - mandibular branch supplies muscles of mastication

Question 9

What are the causes of damage to the cutaneous branches of the CN5 trigeminal nerve?

Answer 9

Facial trauma

Orbital trauma

Question 10

How are the functions of the CN5 trigeminal nerve tested?

Answer 10

General sensory - test sensation in dermatomal areas relating to opthalmic, maxillary and mandibular branches, corneal reflex

Motor - test muscles of mastication

Question 11

What is the corneal reflex?

Answer 11

Gently touching the cornea

should cause blinking of both eyes

Question 12

Whar are the nerves involved in the corneal reflex?

Answer 12

General sensory - trigeminal nerve, opthalmic branch on same side

Motor - facial nerve, temporal and zygomatic branches supplying orbicularis oculi on both sides

Question 13

What is an important branch of the maxillary branch of the CN5 trigeminal nerve?

Answer 13

Infraorbital nerve

Question 14

What is the function of the infra-orbital nerve?

Answer 14

General sensory - lateral nose, lower eyelid, upper lip

Question 15

What is the route of the infra-orbital nerve from its origin to its innervation?

Answer 15

Passes over floor of orbit

then through the infra-orbital foramen

Question 16

What are the causes of damage to the infra-orbital nerve?

Answer 16

Fracture of floor of orbit

Question 17

How does damage to the infra-orbital nerve present?

Answer 17

Loss of sensation over lower eyelid, lateral nose and upper lip

Question 18

What are the most important branches of the mandibular branch of the CN5 trigeminal nerve?

Answer 18

Inferior alveolar nerve

Lingual nerve

Question 19

What is the route of the inferior alveolar nerve?

Answer 19

Enters mandibular foramen
travels through the mandible bone
emerges from the mental foramen

Question 20

What is the continuation of the inferior alveolar nerve?

Answer 20

Mental nerve

Question 21

Where does the inferior alveolar nerve become the mental nerve?

Answer 21

When it emerges from the mental foramen

Question 22

What are the functions of the mental nerve?

Answer 22

General sensory - chin, lower lip

Question 23

What is the route of the lingual nerve?

Answer 23

Runs medially to inferior alveolar nerve

to tongue

Question 24

What is the function of the lingual nerve?

Answer 24

General sensory - anterior two thirds of tongue

Question 25

What are the causes of damage to the inferior alveolar nerve, mental nerve?

Answer 25

Fracture of mandible

Question 26

How does damage to the inferior alveolar nerve, mental nerve present?

Answer 26

Loss of sensation over chin and lower lip

Question 27

What are the effects of damage to the ophthalmic branch of the CN5 trigeminal nerve on the eye?

Answer 27

Loss of sensation over conjunctiva and cornea | loss of corneal reflex

Question 28

What are the consequences of loss of the corneal reflex?

Answer 28

Particles in eye not felt, no blinking to remove them | damage to cornea, may lead inflammation and scarring, loss of vision