Cranial nerve V (Trigeminal nerve)

Question 1

What is CN V

What are the main functions of this nerve

Answer 1

Trigeminal nerve

Sensory, Motor only

Question 2

Where is the trigeminal nerve found in the brainstem

Answer 2

Roots found at lateral pons

Largest nerve with sensory and motor function

Question 3

What are the functions of the trigeminal nerve

Answer 3

Sensory for face
Motor for mastication
-masseter
-temporal
-pterygoid
-digastric

Question 4

What is the name of the main sensory nucleus associated with the trigeminal nerve
What are the 3 subdivisions of nuclei found here

What is the name of the other nucleus associated with the trigeminal nerve

Answer 4

Sensory nucleus of V from trigeminal ganglion outside BS

• Mesencephalic (at level of superior colliculus)
• Chief
• Spinal (at level of spinal cord and medulla oblongata)

Motor nucleus (at level of chief nucleus in the pons)

Question 5

What are the 3 subdivisions of the sensory trigeminal nerve

What areas do they innervate

Answer 5

Ophthalmic division => opthalmic nerve

• forehead
• nasal cavity

Maxillary division => maxillary nerve

• cheek
• nasal cavity
• teeth, upper lip

Mandibular division => mandibular nerve

• Lower lip
• chin, jaw
• External ear

Question 6

Describe the sensory pathway of the Ab fibres into the sensory nucleus

Answer 6

Ab fibres pass via trigeminal ganglion and receive
-discriminative touch => chief nucleus

2nd order neurones to thalamus via medial leminiscus with gracilis and cuneate

Synapse with cerebral cortex

Question 7

Describe the sensory pathway of thin Ad and C fibres into the sensory nucleus

Answer 7

Thin Ad, C fibres via trigeminal ganglion and receive
-pain and temp sensation => spinal nuclei

2nd order neurones to thalamus via spinothalamic tract

Question 8

Describe the sensory pathway of Aa fibres into the sensory nucleus

Answer 8

Aa proprioceptive fibres from lower jaw bypass ganglion => mesencephalic nucleus

Fibres sent up to thalamus to mediate conscious proprioception
Also synapse with motor nucleus in reflex action

Question 9

Describe the motor pathway of the trigeminal nerves to the 4 effector muscles

Answer 9

Motor fibres from motor nucleus bypass ganglion

Innervate muscles in mastication

• masseter
• pterygoid
• temporalis
• digastric

Question 10

What foramen is associated with each branch of the trigeminal nerve

Answer 10

Ophthalmic => superior orbital fissure (w III, IV, VI)
Maxillary => foramen rotundum
Mandibular => foramen ovale