Cranial Nerves Flashcards
One of the main differences between spinal nerves and cranial nerves?
Spinal nerves are both sensory and motor; cranial nerves can be both, or can be just motor or just sensory
Taste is carried by which cranial nerves? (3)
Facial (VII), glossopharyngeal (IX), and vagus (X)
Autonomic difference between spinal nerves and cranial nerves
Cranial nerves do not carry sympathetic fibers (all sympathetics in head are postsynaptic); spinal nerves carry sympathetic fibers
Where do cranial nerves synapse?
Superior cervical ganglion
Which cranial nerves carry parasympathetics? (4)
These target what muscles?
CN III, VII, IX, and X
Smooth muscles of the eye
In regard to the 4 cranial nerves that carry parasympathetics, which has a unique target, where is it?
Vagus nerve targets are outside head
Name all 12 cranial nerves in order
Olfactory, optic, oculomotor, trochlear, trigeminal, abducens, facial, vestibulocochlear, glossopharyngeal, vagus, accessory and hypoglossal
Which 4 cranial nerves move the eye muscles
III, IV, V, and VI
Difference in location of the special sensory nerves compared to the other cranial nerves?
Special sensory nerves emerge from the forebrain; other cranial nerves emerge from the brainstem
What are the 2 special sensory nerves?
Olfactory and optic
Olfactory nerve (CN I)
- Function
- Location
- Where do the fibers extend into?
- Other function that can help intensify your sense of smell?
- Sense of smell
- Cribriform plate of ethmoid bone
- Fibers go through holes of cribriform plate to the upper 1/3 of nasal cavity
- Moistening the air
~so only upper 1/3 of nasal cavity has a sense of smell
Optic nerve (CN II)
- Emerges from?
- Where do they crossover?
- What do they form after they crossover?
- Optic canal
- Optic chiasm
- Form optic tracts
Optic field for LEFT eye:
- Light coming from the left will go to which field?
- Light coming from the right will go to which field?
- At the optic chiasm, the signal from the nasal field of the left eye goes which direction? Temporal field?
- Temporal field of left eye (medial part of eye)
- Nasal field of left eye (lateral part of eye)
- Nasal field goes to the left of the left eye; temporal field goes to the right of the left eye
Optic field for RIGHT eye:
- Light coming from the left will go to which field?
- Light coming from the right will go to which field?
- At the optic chiasm, the signal from the nasal field of the right eye goes which direction? Temporal field?
- Nasal field of right eye
- Temporal field of right eye
- Nasal field will go right of the right eye; temporal field will go left of the right eye
Monocular blindness:
1. If you have a problem with your left optic nerve, you will have blindness in which 2 fields of view?
- Blindness in temporal AND nasal field of left eye
Homonymous hemianopia:
- This is loss of vision where?
- Can be due to an injury of the?
- So right optic tract will injure the __ side of both eyes
- So if your right optic tract is injured, you will lose vision where?
- If your left optic tract is injured, you will lose vision where?
- In 1/2 of your eye on same side in both eye (so either right sides of both eyes or left sides of both eyes)
- Optic tract
- Right side of both eyes; left optic tract will injure left sides of both eyes
- Right nasal field and left temporal field
- Left nasal field and right temporal field
Bitemporal hemianopia:
- Aka ?
- Damage to? Can be caused from?
- Removes function where?
- Tunnel vision
- Optic chiasm; can happen if pituitary gland is enlarged
- Lose function in temporal field of both left and right eye
4 simple motor cranial nerves
Oculomotor, abducens, trochlear, and hypoglossal
Oculomotor:
- Motor function?
- Other key feature of this nerve?
- Moves extrinsic eye muscles
2. *Carries parasympathetic fibers
Abducens:
1. Innervates what muscle?
- Lateral rectus muscle (an extrinsic eye muscle)
Trochlear:
1. Innervates what muscle
Superior oblique (also an extrinsic eye muscle)
Hypoglossal:
1. Innervates? Exception
Innervates all tongue muscles except palatoglossus
All other cranial nerves not described are called?
Branchial nerves
Trigeminal nerve provides sensory innervation where?
Eyes, orbital contents, face, teeth, nasal/oral cavities, sinuses, dura, anterior external ear, and part of external acoustic meatus
Which branch of the trigeminal nerve also provides motor innervation?
What 5 muscles does it innervate?
V3 (branchial motor)
Muscles of mastication, mylohyoid, anterior digastric, tensor tympani, and tensor veli palatini
Does trigeminal nerve have parasympathetic fibers?
However?
No
It is a common relay pathway for parasympathetic and sensory components of other cranial nerves
Facial nerve:
- Special sensory component?
- Somatic sensory component?
- Visceral motor (parasympathetic) component?
- Branchial motor component?
- Taste to anterior 2/3 of tongue (chorda tympani)
- External acoustic meatus
- Lacrimal and oronasal mucus glands and salivary glands (except parotid)
- Muscles of facial expression, stapedius, stylohyoid, and posterior digastric
Course of the facial nerve:
- Facial nerves branch within?
- Function of greater petrosal nerve
- Stapedial branch supplies?
- Chorda tympani carries? Along which nerve?
- Where do motor branches of facial nerve exit?
- Petrous pyramid
- Carries parasympathetics to pterygopalatine ganglion
- Stapedius muscle
- Parasympathetic and taste fibers along lingual nerve (part of CN V3)
- Exit the stylomastoid foramen
How does the parasympathetic nerve signal travel to submandibular/sublingual glands (6 steps starting with facial nerve)
Facial nerve -> chorda tympani -> exits via petrotympanic fissure -> travels with lingual nerve -> synapses on submandibular ganglion -> then lingual nerve carries parasympathetics to the submandibular/sublingual glands
How does the parasympathetic nerve signal travel to lacrimal gland/mucosa of the nose and palate (7 steps starting with facial nerve)
Facial nerve -> greater petrosal nerve -> travels across medial cranial fossa -> joined by deep petrosal nerve (sympathetics) -> nerve to pterygoid canal -> synapse on pterygopalatine ganglion -> to targets via many branches of V2
What type of nerve fibers synapse in the various ganglia of the face?
Parasympathetics; sympathetics have already synapsed elsewhere
Why is vestibulocochlear nerve not considered a special sensory nerve even though it is for hearing and balance?
It isn’t technically just a part of the brain like the other 2; it is technically from the facial nerve
Glossopharyngeal nerve:
- Special sensory component?
- Somatic sensory component?
- Visceral sensory component?
- Visceral motor (parasympathetic) component?
- Branchial motor component
- Taste to posterior 1/3 of tongue
- Posterior 1/3 of tongue, middle ear, oropharynx, pharyngotympanic tube, and mastoid
- Carotid body and carotid sinus
- Parotid gland
- Stylopharyngeus muscle
Difference between what the carotid body and carotid sinus detect
Carotid body- chemosensation
Carotid sinus- blood pressure
Steps that parasympathetics take from glossopharyngeal to parotid gland?
CN IX -> tympanic nerve -> through tympanic caniliculius -> forms plexus in middle ear -> lesser petrosal nerve -> travels across middle cranial fossa -> through foramen ovale -> synapse in otic ganglion -> auriculotemporal nerve carries parasympathetics to parotid gland
Vagus nerve:
- Special sensory part?
- Somatic sensory part?
- Visceral sensory part?
- Visceral motor (parasympathetic) part?
- Branchial motor part?
- Taste from epiglottis/pharynx
- Larynx, laryngopharynx, part of external acoustic meatus
- Thoracic and abdominal viscera (excluding hindgut), chemo/baroreceptors
- Thoracic and abdominal viscera (excluding hindgut)
- Muscles to pharynx, larynx, soft palate (except stylopharyngeus and tensor veli palatini)
Certain fibers of the vagus nerve are associated with what nerve?
Spinal accessory nerve (CN XI)
Which cranial nerves are sensory, motor, or both (go in order)
Sensory, sensory, motor, motor, both, motor, both, sensory, both, both, motor, motor
~Some say marry money but my brother says big brains matter more
There are exceptions (like if there are two of the words in the name) but generally:
- All muscles in the head with “tensor” in the name are innervated by?
- Muscles with the letters “palat” are innervated by?
- Muscles with “gloss” are innervated by?
- CN V3
- CN X
- CN XII
