Cranial Nerves Flashcards
1
Q
- How many paired cranial nerves are there?
- Why are they considered cranial nerves?
- What do they connect to?
- Which are the 2 exceptions?
A
- 12
- they exit from cranial foramina or fissures
- connect to nuclei on brainstem
- CN I and CN II (they involve extensions of the forebrain)
2
Q
- What comes from the posterior side of the midbrain and has the longest intracranial length of all the cranial nerves?
- What nerve comes off the midbrain-pontine junction?
- What nerve comes off pons (vague)?
- What nerves comes off pontine-medulla junction?
- What nerves come off medulla oblongata, posterior to the olive and anterior to the olive?
- What nerve comes off the cervical spinal cord?
A
- trochlear n (CN IV)
- oculomotor (CN III)
- trigeminal (V)
- abducens, facial, vestibulocochlear (CN VI-VIII)
- posterior: glossopharyngeal, vagus (CN IX, X), anterior: hypoglossal (CN XII)
- accessory XI
3
Q
What are the different functions of cranial nerves (different fibers)?
A
- GSE: voluntary muscle
- GVE: smooth muscle/glands (parasympathetic not sympathetic)
- GSA: somatic sensory
- GVA: visceral sensory
- special sense: taste, smell, hearing, balance, vision
4
Q
- Which cranial nerves are the origin of parasympathetic fibers in the head?
- What do parasympathetic fibers go to?
- Which cranial nerve is the origin of parasympathetics in the thorax and abdomen?
A
- CN III, VII, and IX
- lacrimal glands, submandibular glands, sublingual glands, nasal glands, sphincter pupillae m and ciliary bodies
- CN X
5
Q
- Where do all sympathetic fibers in the head come from?
- What do they course up with?
- What do they provide sympathetic fibers to?
A
- lateral horn of thoracic spinal cord, up sympathetic chain, and synapse in superior cervical ganglion
- external or internal carotid a via carotid plexus and follow same course as parasympathetics
- lacrimal glands, submandibular glands, sublingual glands, nasal glands, dilator pupillae, levator palpebrae superioris
6
Q
What do sympathetic fibers do for these structures:
- pupil
- lacrimal glands
- nasal mucosa
- submandibular and sublingual glands
- parotid glands
A
- pupil dilation
- decrease lacrimation
- decrease secretion
- decrease salivation
- decrease salivation
7
Q
What do parasympathetic fibers do to these structures and what nerves are associated with them?
- sphincter pupilae m
- ciliary bodies
- lacrimal gland
- nasal mucosa
- submandibular and sublingual gland
- parotid gland
A
- pupil constriction; CN III
- relax lens; CN III
- Increase lacrimation; CN VII
- increase secretion; CN VII
- increase salivation; CN VII
- increase salivation; CN IX
8
Q
- What is the function of CN I (olfactory)?
- What foramen does it go through?
- This nerve does not come from (…), it involves an (…) of the forebrain
- The olfactory nerves are the only CN to enter what directly?
- The (…) extend to the distal part called olfactory bulb which gives rise to around 20 olfactory nerves
- The olfactory nerves penetrate the (…) of the (…) bone which lies on the medial superior nasal cavity
A
- special sense (olfaction)
- cribriform foramina
- brainstem; extension of the forebrain
- enter cerebrum directly
- olfactory tracts
- cribriform plate of the ethmoid bone
9
Q
- What is the function of CN II (optic)?
- What foramen does it go through?
- These are (…) of the forebrain
- Fibers from nasal half of each retina decussate in the (…) to join the temporal half of the uncrossed fibers from the retina to form the (…)
- What does this give us?
A
- special sense (vision)
- optic canal
- anterior extensions of the forebrain
- chiasm; optic tract
- binocular vision; depth perception
10
Q
What are the only two CN that do not come off the midbrain, pons, or medulla?
A
CN I and II
11
Q
- What fibers does CN III (oculomotor) provide?
- What muscles are associated with these fibers?
- What foramen does CN III go through?
- CN III emerges from (…) and runs through the lateral wall of the (…)
- After leaving the cranial cavity the parasympathetic fibers synapse in the (…) then travel through the (…) to innervate the (…) m. and (…) in the (…)
A
- GSE: extrinsic eye mm except SO and LR; levator palpebri superioris
- GVE: sphincter pupillae m (pupil constriction), ciliary bodies (accommodation/near sight)
- superior orbital fissure
- emerges from midbrain; runs through cavernous sinus
- ciliary ganglion, short ciliary nn, sphincter pupillae m, ciliary mm in the ciliary bodies
12
Q
- What CN do special sense?
- What CN provide parasympathetic fibers?
- What CN run through cavernous sinus?
A
- I, II, and VIII
- CN III, VII, IX, X
- III, IV, V1,V2, VI
13
Q
- What is the function of CN IV (trochlear)?
- What foramen does it run through?
- This is the (…) CN and emerges from the posterior surface of the (…)
- What does this nerve innervate?
- What actions does this muscle do?
A
- GSE to superior oblique
- superior orbital fissure
- smallest; midbrain
- superior oblique m
- intorsion, abduction, depression of the eye
14
Q
- What is the function of CN V (trigeminal)
- What foramen does it run through?
A
function:
- GSA: vast majority is sensory around head
- GSE: CN V3 only division that has somatic motor (muscles of mastication)
foramen:
- CN V1: superior orbital fissure
- CN V2: foramen rotundum
- CN V3: foramen ovale
15
Q
What serves as the main highway for autonomics as it has very extensive branching and innervation around the head?
A
trigeminal nerve (CN V)
16
Q
What does CN V emerge from?
A
The pons
17
Q
- What is the function of CN V1?
- What foramen does CN V1 go through?
- What are the branches CN V1 gives off?
A
- GSA: orbital region
- superior orbital fissure
branches: - nasociliary (short and long ciliary nn)
- frontal n (supraorbital n, supratrochlear n)
- lacrimal n
18
Q
What do the branches of the ophthalmic nerve (V1) supply?
A
nasociliary:
- short ciliary n: nasal mucosa and skin
- long ciliary n: cornea (corneal reflex)
frontal:
- supraorbital and supratrochlear: skin of forehead
lacrimal:
- lacrimal gland, conjuctiva, eyelid
19
Q
- What is the function of CN V2?
- What foramen does it run through?
- This branch does sensory to the (…) and (…)
- It also carries parasympathetics to the (…) to (…) secretions
A
- GSA - maxillary region
- foramen rotundum
- skin of maxillary region, nasal mucosa
- nasal mucosa, increase secretions
20
Q
- What nerve carries parasympathetics via CN III for pupil constriction and accommodation?
- What nerve carries sympathetics via the superior cervical ganglion for pupil dilation?
- What nerve carries parasympathetics via CN VII for salivation?
A
- short ciliary nn
- long ciliary nn
- lacrimal n
21
Q
- What is the function of CN V3?
- What foramen does it go through?
A
- GSA: mandibular region
- GSE: muscles of mastication, tensor twins, mylohyoid m, and anterior belly of digastric m
- foramen ovale
22
Q
What are the branches of CN V3 and what structures do they supply?
A
- muscular branches: muscles of mastication and tensor twins
- auriculotemporal n: parotid gland
- buccal n: cheek and mucosa and skin
- lingual n: tongue, submandibular/sublingual glands; tongue
- inferior alveolar: mandibular teeth
- n to mylohyoid: mylohyoid and anterior belly of digastric
- mental n: skin of chin
23
Q
- What carries parasympathetic fibers to parotid gland for salivation?
- What carries parasympathetic fibers of the submandibular and sublingual glands for salivation?
- What carries special sense to anterior 2/3 tongue via chorda tympani n?
A
- auricotemporal n
- lingual n
- lingual n
24
Q
- What are the muscles of mastication?
- What are the tensor twins?
A
- masseter, temporalis, medial pterygoid, lateral pterygoid
- tensor tympani, tensor veli palatini
25
What muscles does the mandibular branch of CN V innervate?
- masseter m
- temporalis m
- medial pterygoid m
- lateral pteryoid
- tensor tympani
- tensor veli palatini
- mylohyoid
- anterior belly of digastric
26
- What is the function of abducens (CN VI)?
- What foramen does it go through?
- It emerges from the brain between what?
- It has the longest (...) course within the cranial cavity
- What does this nerve innervate?
- What is the action of this muscle?
- GSE to lateral rectus
- superior orbital fissure
- pons and medulla
- intradural
- lateral rectus m
- abducts eye
27
What nerves innervate the muscles of the eye and what are their associated muscles?
- CN III: SR, IR, MR, IO
- CN IV: SO
- CN VI: LR
28
- How many types of mixed fibers does the facial nerve give off?
- What do these mixed fibers do/supply?
- GSA: external auditory canal, some external ear
- GSE: muscles of facial expression, stapedius m, stylohyoid, posterior belly of digastric
- GVE: parasympathetics to lacrimal gland, submandibular and sublingual glands
- Special sense: taste (anterior 2/3)
29
- What foramen does the facial nerve run through?
- What does this nerve emerge from?
- What does it exit the cranial cavity through?
- Within the temporal bone, what does this nerve give off (what branches)?
- What is attached to the stapes?
- What does this muscle do?
- internal acoustic meatus and stylomastoid foramen
- junction of pons and medulla
- internal acoustic meatus
- greater petrosal n, stapedius n, chorda tympani n
- stapedius m
- dampens loud sounds
30
- What does the greater petrosal n give off?
- What does the nerve to stapedius do?
- What does the chorda tympani n do?
- parasympathetics
- motor to stapedius m
- taste and parasympathetics
31
What is the pathway of parasympathetics to the lacrimal gland from CN VII?
- CN VII → greater petrosal n → n of pterygoid canal
- fibers synapse, some hitch a ride on V2 → nasal mucosa → increase secretion
- some hitch a ride on V1 from zygomatic → lacrimal n → lacrimal gland → increase lacrimation/salivation
32
What is the pathway of parasympathetics to the submandibular and sublingual glands from CN VII?
CN VII → chorda tympani → submandibular ganglion → hop on V3 → submandibular and sublingual gland → increase salivation
33
- CN VII leaves the temporal bone through what foramen?
- What does it give off after this?
- What are the terminal branches?
- stylomastoid foramen
- posterior auricular branch
*terminal branches:*
- temporal
- zygomatic
- buccal
- marginal mandibular
- cervical
34
- What is the function of CN VIII (Vestibulocochlear n)?
- What foramen does it go through?
- What does it emerge from?
- What does it enter?
- What does it separate into?
- special sense (nearing and equilibrium/motion)
- internal acoustic meatus
- junction of pons and medulla
- internal acoustic meatus
- vestibular and cochlear nerves
35
- What does the vestibular n of CN VIII innervate?
- What does the cochlear n do and what is it found it?
- maculae of utricle and saccule; crista ampullaris of semicircular ducts (equilibrium and motion)
- deals with hearing, found in cochlear duct (organ of corti)
36
- What are the different mixed fibers that CN IX (glossopharyngeal) provides?
- What do these fibers do/provide sensation to?
- GSA: posterior 1/3 of tongue, oropharynx (gag reflex), middle ear
- GSE: stylopharyngeus m
- GVE: parasympathetic to parotid gland (otic)
- special sense: taste (posterior 1/3)
37
- What foramen does CN IX go through?
- What does it emerge from?
- jugular foramen
- medulla
38
What is the pathway of parasympathetic from CN IX?
CN IX → tympanic n → lesser petrosal n → otic ganglion → hops on V3 (auricotemporal) → parotid gland → increase salivation
39
- What are the different types of mixed fibers that CN X provides?
- What do these fibers do?
- GSA: external auditory canal, larynx
- GSE: pharyngeal constrictor mm, palatopharyngeus m, salpingopharyngeus m, levator veli palatini, palatoglossus, uvula, laryngeal m
- GVA: thorax and abdomen
- GVE: parasympathetic to thorax and abdomen
- special sense: taste; contribution from root of tongue and the epiglottis
40
- What foramen does CN X go through?
- What does it emerge from?
- What does it exit through?
- This nerve has the (...) of any CN as it travels down to the left colic flexure
- jugular foramen
- medulla
- jugular foramen between CN IX and CN XI
- largest course
41
- What is the function of CN XI?
- What foramen does it go through?
- What does it emerge from?
- GSE to SCM and trapezius
- foramen magnum, exits jugular foramen
- anterior rootlets of the first 6 cervical spinal cord segments
42
- What is the function of CN XII (hypoglossal n)?
- What does it go through?
- What does it emerge from?
- After exiting the cranial cavity, motor fibers from (...) hitch a ride on CN XII to innervate the (...) muscles but these are not (...) fibers
- GSE to styloglossus, hyoglossus, genioglossus, and intrinsic tongue mm
- hypoglossal canal
- medulla
- C1 and C2; CN XII fibers
43
What CN nerves do pharyngeal (branchial) arches and muscular innervation?
- CN V3
- CN VII
- CN IX
- CN X
44
What are the stern's rules for CN innervation?
1. "tensor" = CN V3 (tensory veli palatini and tensor tympani)
2. "palato-" = CN X (except tensor veli palatini b/c 1st rule)
3. tongue/"glosso" = CN XII (except palatoglossus m b/c of 2nd rule)
45
Which CNs deal with eye movement?
- CN III
- CN IV
- CN VI
46
Which CN originate parasympathetic fibers?
- CN III
- CN VII
- CN IX
- CN X
47
What nerves go through cribriform plate?
olfactory n (CN I)
48
What nerves go through optic canal?
optic nerve (CN II)
49
What nerves go through superior orbital fissue?
- oculomotor (CN III)
- trochlear (CN IV)
- ophthalmic (CN V1)
- abducens (CN VI)
50
What nerve goes through foramen rotundum?
maxillary (CN V2)
51
What nerve going through foramen ovale?
mandibular n (CN V3)
52
What nerves go through internal acoustic meatus?
- facial n (CN VII)
- vestibulocochlear (CN VIII)
53
What nerves go through jugular foramen?
- glossopharyngeal (CN IX)
- vagus (CN X)
- accessory n (CN XI)
54
What nerves go through hypoglossal canal?
hypoglossal n (CN XII)
