Lecture 1 - Cranial Nerves Flashcards
List the 12 cranial nerves from rostral to caudal.
- Olfactory
- Optic
- Oculomotor
- Trochlear
- Trigeminal
- Abducens
- Facial
- Acoustic
- Glossopharyngeal
- Vagus
- Accessory
- Hypoglossal
How to remember the function of each cranial nerve?
Some say marry money but my brother says big brains matter more
S: sensory (olfactory nerve - CN I) S: sensory (optic nerve - CN II) M: motor (oculomotor nerve - CN III) M: motor (trochlear nerve - CN IV) B: both (trigeminal nerve - CN V) M: motor (abducens nerve - CN VI) B: both (facial nerve - CN VII) S: sensory (vestibulocochlear nerve - CN VIII) B: both (glossopharyngeal nerve CN IX) B: both (vagus nerve - CN X) M: motor (spinal accessory nerve - CN XI) M: motor (hypoglossal nerve - CN XII)
Cranial nerve mnemonic?
Oh, Oh, Oh, To Touch And Feel A Girl’s Vagina and Hymen
What cranial nerves are found in the forebrain?
1 and 2
What cranial nerves are found in the brainstem?
3 to 12
Do cranial nerves provide both somatic and visceral innervation?
YUP
Do cranial nerves provide both sympathetic and parasympathetic innervation?
NOPE, only parasympathetic
What 3 types of innervation do cranial nerves provide?
- Somatic
- Visceral
- Special sensory
What are the 5 special senses that cranial nerves provide innervation for?
- Vision
- Smell
- Taste
- Hearing
- Equilibrium
Function of olfactory nerve?
Olfaction
Function of optic nerve?
Vision
Function of trochlear nerve?
Serves the superior oblique eye muscle to facilitate intorsion, abduction, and depression of the eyeball = eye looking down and laterally
Functions of trigeminal nerve?
- Sensory from face and mouth
2. Motor to muscles of mastication
Function of abducens nerve?
Serves the lateral rectus eye muscle to faciliate abduction of the eyeball
Functions of facial nerve?
- Serves the muscles of facial expression
- Serves parasympathetic innervation to all face glands except for the parotid gland
- Special sensory from anterior 2/3 of tongue and palate
What are the lacrimal glands?
Paired, almond-shaped glands, one for each eye, that secrete the aqueous-layer of the tear film
Functions of the vestibulocochlear nerve? How many branches does it have?
- Equilibrium
- Hearing
2 branches (one for each sense)
Functions of the glossopharyngeal nerve? Most important one?
- **SENSORY:
1. General/somatic sensory for posterior third of tongue, pharynx, back of palate, middle ear, and Eustachian tube
2. Visceral sensory from carotid baro/chemoreceptors
3. Special sensory from posterior third of tongue
MOTOR:
- Somatic innervation to 1 muscle of the pharynx for swallowing
- Parasympathetic innervation of parotid gland
Functions of the vagus nerve?
SENSORY:
- General/somatic sensory innervation from structures in the lower pharynx and larynx and ear
- Visceral sensory from visceral organs and chemo/baroreceptors in aorta (thorax)
MOTOR:
- Somatic innervation of 1 intrinsic tongue muscle (palatoglossus) and most muscles of the soft palate, pharynx, and larynx (phonation)
- MAJOR Parasympathetic regulation of visceral organs and glands in thorax, abdomen (foregut and midgut), pharynx, and larynx
Function of accessory nerve?
Serves muscles that move head, neck, and shoulders: trapezius and sternocleidomastoid muscles
Function of hypoglossal nerve?
Somatic motor to all muscles of the tongue (except palatoglossus)
What is the pathway of smell?
Olfactory epithelium in upper nasal cavity with olfactory cilia and dendrites (these all constitute CN I) => ethmoid bone => synapse with olfactory bulb (termination of nerve) => olfactory tract => olfactory cortex of the cerebrum
What is the pathway of vision?
Photoreceptors (rods and cones) in retina => ganglion cell layer => converge to form CN II => optic chiasm => optic tracts => synapse at thalamus => synapse at visual cortex of cerebrum
What is the optic chiasm close to?
Pit gland
What do optic nerves connect?
Connect the retina to the optic chiasm
Which optic fibers decussate at the optic chiasm?
The fibers from the medial side of the retina (peripheral vision)
What are optic tracts?
Optic fibers starting at the optic chiasm
What do optic chiasm lesions (or pituitary tumors) cause?
Bi-temporal hemianopsia
What is hemianopsia?
Visual field loss on the left or right side of the midline
What is homonymous hemianopsia?
Visual field loss on the same side of both eyes