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
