Cranial Nerves (Ch. 15) Flashcards
(44 cards)
Cranial Nerves: Overview
Part of PNS
Sensory, motor, and parasympathetic nerve fibers that innervate the head and viscera
Where do cranial nerves originate?
Brain or brainstem
How are the cranial nerves named?
Named in order, from anterior to posterior, where they emerge from the brain
How many cranial nerve (pairs) are there?
12 pairs (CN 1 - CN 12)
How many sensory, motor, and mixed nerve pairs exist?
3 pairs of sensory nerves
5 pairs of motor nerves
4 pairs of mixed nerves (both sensory and motor)
List all 12 cranial nerves in order (CN 1 - CN 12)
- Olfactory (CN 1)
- Optic (CN 2)
- Oculomotor (CN 3)
- Trochlear (CN 4)
- Trigeminal (CN 5)
- Abducens (CN 6)
- Facial (CN 7)
- Vestibulocochlear (CN 8)
- Glossopharyngeal (CN 9)
- Vagus (CN 10)
- Spinal Accessory (CN 11)
- Hypoglossal (CN 12)
What is the mnemonic for the cranial nerves?
On [Olfactory (CN 1)] On [Optic (CN 2)] On [Oculomotor (CN 3)] They [Trochlear (CN 4)] Traveled [Trigeminal (CN 5)] And [Abducens (CN 6)] Found [Facial (CN 7)] Voldemort [Vestibulocochlear (CN 8)] Guarding [Glossopharyngeal (CN 9)] Very [Vagus (CN 10)] Secret [Spinal Accessory (CN 11)] Horcruxes [Hypoglossal (CN 12)]
Which 2 cranial nerves attach to the forebrain?
Olfactory (CN 1) and Optic (CN 2)
Where do the rest of the cranial nerves attach?
At the brainstem
Which is the only cranial nerve to extend past the head and neck?
Vagus nerve (CN 10)
What are the 3 axons cranial nerves can carry?
Sensory axons (S) Motor axons (M) Both axons (B)
Which 3 cranial nerves carry sensory axons?
Olfactory (CN 1)
Optic (CN 2)
Vestibulocochlear (CN 8)
Which 5 cranial nerves carry motor axons?
Oculomotor (CN 3) Trochlear (CN 4) Abducens (CN 6) Spinal Accessory (CN 11) Hypoglossal (CN 12)
Which 4 cranial nerves carry both sensory and motor axons?
Trigeminal (CN 5)
Facial (CN 7)
Glossopharyngeal (CN 9)
Vagus (CN 10)
What’s the mnemonic for determining which cranial nerves carry S, M, or B axons?
Some [Olfactory (CN 1)] Say [Optic (CN 2)] Money [Oculomotor (CN 3)] Matters [Trochlear (CN 4)] But [Trigeminal (CN 5)] My [Abducens (CN 6)] Brother [Facial (CN 7)] Says [Vestibulocochlear (CN 8)] Big [Glossopharyngeal (CN 9)] Brains [Vagus (CN 10)] Matter [Spinal Accessory (CN 11)] Most [Hypoglossal (CN 12)]
3 Sensory Cranial Nerves
Olfactory (CN 1), Optic (CN 2), Vestibulocochlear (CN 8)
Innervation for special sensory structures (smell, vision, equilibrium, and hearing)
Olfactory Nerve (CN 1) [S]
Sensory: olfaction (smell)
Origin: olfactory epithelium of nose (terminate in posterior olfactory cortex)
Optic (CN 2) [S]
Technically not a nerve but a brain tract (we still call it a nerve)
Sensory: vision
Origin: retina of eye (terminal in primary visual cortex [posterior part of occipital lobe])
Vestibulocochlear (CN 8) [S]
Sensory: hearing and balance (equilibrium)
Origin: inner ear, enters brain stem at pons
5 Motor Cranial Nerves
Oculomotor (CN 3), Trochlear (CN 4), Abducens (CN 6), Spinal Accessory (CN 11), and Hypoglossal (CN 12)
Somatic motor fibers to skeletal muscles of eye, neck/back, and tongue
Oculomotor (CN 3), Trochlear (CN 4), Abducens (CN 6) [M]
Oculomotor (CN 3):
- -origin: midbrain
- -also parasympathetic
Trochlear (CN 4):
–origin: midbrain
Abducens (CN 6):
–origin: pons
Fxn: all of these are primarily motor nerves to extrinsic eye muscles
Problems with Eye Innervation
When the nerve(s) that control the muscles that move the eye are damaged, lots of potential issues. Conditions include strabismus (eyes not parallel), ptosis (drooping eyelids), and diplopia (double vision)
Spinal Accessory Nerve (CN 11) [M]
Motor nerve to trapezius and sternocleidomastoid muscles
Origin: rootlets at cervical region of spinal cord
Hypoglossal (CN 12) [M]
(Hypo = below; global = tongue)
Motor to tongue muscles
Origin: medulla oblongata
