Cranial nerves: Sensory and Motor Flashcards
1
Q
What bone is the cribiform plate located in?
A
Ethmoid
2
Q
What is the olfactory region?
A
Upper third of the nasal cavity (superior nasal concha, roof of nasal cavity and nasal septum)
3
Q
What is the olfactory bulb anchored by?
A
Dura mater
4
Q
What do axons of the neurons in the olfactory bulb form?
A
Olfactory tract
5
Q
Where do olfactory axons project to?
A
Olfactory cortex first and then to the limbic system, hypothalamus and reticular formation
6
Q
What is the only sense which reaches the cortex first then goes to the thalamus?
A
OLfactory - smell
7
Q
What cells can differentiate to bipolar (olfactory) neurons?
A
Basal cells
8
Q
What is anosmia?
A
Loss of smell
9
Q
What can ansomia be caused by?
A
- Olfactory neuropathy caused by upper respiratory tract infection
- Trauma, causing the brain and olfactory bulb to move may tear the olfactory nerves
10
Q
What can fractures of the cribiform plate (on ethmoid) cause?
A
CSF rhinorrhoea (blood stained CSF leaking from the nose)
11
Q
What do the cilia on bipolar neurons act like?
A
Receptors - activated by other molecules which must be dissolved in mucus (mucus glands therefore help olfaction)
12
Q
What is the average lifespan of bipolar neurons?
A
40 - 60 days (basal cells turn into bipolar) (only neurons in adult humans that can be regenerated)
13
Q
What is the largest cranial nerve?
A
Trigeminal nerve (CN V) (mixed nerve)
14
Q
What divisions of the trigeminal are afferent only?
A
V1 and V2
15
Q
What division of the trigeminal nerve is both afferent and efferent?
A
V3
16
Q
What are the 4 nuclei (and 2 roots)?
A
- Sensory roots: to mesencephalic nucleus, principal (pontine) nucleus, spinal nucleus
- Motor root: from motor nucleus
17
Q
Nerves crrying what senses terminate on what nucleus?
A
Mesencephalic
18
Q
What fibres terminate on the principal or pontine nucleus?
A
Touch and pressure
19
Q
What fibres terminate on the spinal nucleus?
A
Pain and temperature
20
Q
Where do the sensory and motor roots of CNV emerge
A
Mid-pons and run towards the trigeminal ganglion
21
Q
What do the 3 divisions of the trigeminal nerve emerge from?
A
Trigeminal ganglion
22
Q
What type of fibres does the opthalmic nerve carry?
A
- Sensory
- Sympathetic fibres from the carotid plexus are carried along with it
23
Q
What branch does the opthalmic nerve give off near the trigeminal ganglion that supplies the dura?
A
Meningeal branch
24
Q
What are the 3 main branches of the opthalmic nerve?
A
- Lacrimal
- Frontal
- Nasociliary
25
What does the lacrimal nerve supply?
General sensation to the lacrimal gland, conjunctiva and upper eyelid in vicinity of Lacrimal gland
26
What does the opthalmic nerve also carry?
Parasympathetic fibres of fascial nerve to the lacrimal glans
27
What does the frontal nerve supply?
Largest branch of opthalmic
| - Supplies upper eyelid and conjunctiva, frontal sinus and the scalp as far back as vertex
28
What does the frontal nerve divide into?
Supra-orbital and supra-trochlear nerves
29
What are the branches of the nasociliary nerve?
- Long ciliary nerves
- Ant and post ethmoidal
- Infratrochlear nerve
30
What does the nasociliary nerve supply sensation to?
- Cornea of the eye -> Afferent limb of cornea reflex
| - Tip of the nose (shingles can spread from here to cornea)
31
What kind of fibres are carried by the maxillary nerve (V2)?
Sensory
32
The maxillary nerve sends zygomatic and infra-orbital branches via what fissure?
Inferior orbital fissure
33
What does the infra-orbital nerve exit the orbit via?
Infra-orbital canal -> infra-orbital foramen
34
What branches of the maxillary nerve go to the palate and upper teeth?
Palatine and superior alveolar branches
35
What does the maxillary nerve supply sensation to?
- Lateral forehead
- zygomatic region
- Lower lid
- Side of nose
- Cheek (anteriorly)
- Upper lip
36
What fibres are contained in the mandibular nerve?
Sensory and motor
37
What are the branches given off by the mandibular nerve?
- AUriculotemporal
- Buccal
- Lingual
- Inferior alveolar branches
38
What does the mandibular nerve supply sensory information to?
- Skin of auricle and temple
- Cheek, posteriorly
- LOwer lip and chin
- General sensation to the anterior 2/3 of the tongue, and the floor of the mouth
- The lower gums and teeth
39
What is the skin over the angle of the mandible supplied by?
Cervical plexus
40
What does the mandibular nerve supply motor information to?
Muscles of mastication:
- Lateral pterygoid
- Medial pterygoid
- Masseter
- Temporalis
- Tensor tympani
- Tensor veli palatini
- Mylohyoid
- Anterior belly of digastric
41
What nerve is tested in the jaw jerk reflex?
Trigeminal
42
What kind of fibres are carried in the oculomotor nerve?
Somatomotor and visceromotor (parasympathetic)
43
Where is the oculomotor nucleus found?
Midbrain
44
What does the oculomotor nerve pass between?
- Posterior cerebral and superior cerebellar arteries before lying close to posterior communicating arteries
45
What does the oculomotor nerve run anteriorly on?
Lateral wall of the cavernous sinus
46
What does the oculomotor nerve pass through to get to the orbit?
Superior orbital fissure
47
What does the oculomotor nerve divide into?
Superior and inferior divisions (rami)
48
What is the name of the tendinous ring which the superior and inferior divisions of the oculomotor nerve pass through?
Tendinous ring of Zinn
49
What does the superior branch of the oculomotor nerve supply motor nerves to?
- Levator palpebrae superioris
- Superior rectus
Also contains branches from superior cervical ganglion
50
What does the inferior branch of the oculomotor nerve supply?
- Medial rectus muscle
- Inferior rectus muscle
- Inferior oblique
- Ciliary ganglion
51
What kind of muscle is the levator palperbrae superioris?
Mixed - smoot and striated fibres
| - Innervated by both sympathetics and oculomotor
52
What fibres are carried by the trochlear nerve?
Motor only
53
Where is the trochlear nerve nucleus?
Midbrain
54
Where does the trochlear nerve exit the brainstem from?
Posterior surface (only nerve that does this)
55
Describe the pathway taken by the trochlear nerve?
- Exits branistem from posterior surface
- Runs anteriorly around cerebral peduncle and enters cavernous sinus
- Runs anteriorly on lateral wall of cavernous sinus
- Enters through superior orbital fissure
- Enters orbit
- Moves slightly medially
- Supplies superior oblique
56
What muscle does the trochlear nerve supply?
Superior oblique
57
What does injury to the trochlear nerve result in?
- Patient not being able to look medially and inferiorly
| - Patient experiences diplopia (blurred/double vision) while walking downstairs or reading a book
58
Why is the trochlear nerve long and thin?
Only supplies one muscle (superior oblique)
59
What fibres are carried by the abducens nerve?
Motor
60
Where is the abducens nerve nucleus?
Pons
61
Where does the abducens nerve exit the brainstem?
- Medially, anteriorly- between pons and medulla
| - Bulbo-pontine groove
62
What are the 3 nerves which are involved in eye movement?
- Oculomotor
- Trochlear
- Abducens
63
Describe the pathway of the abducens nerve?
- Enters cavernous sinus (within)
- Enter superior orbital fissure
- In orbit supplies lateral rectus muscle
64
What will injury to the abducens nerve result in?
Right abducens nerve will result in:
| - Diplopia when looking right - the right eye would not abduct fully
65
What kind of fibres are carried by the facial nerve?
Mixed - motor, sensory and parasympathetic fibres (one nucleus for each)
66
Where are the nuclei for the facial nerve found?
Pons
67
What are the divisions of the motor nucleus (nucleus solitarius) of the facial nerve?
Superior and inferior divisions which innervate the upper and lower facial muscles, respictively (upper third vs lower 2/3s)
68
What is the superior division of the facial motor nucleus connected to?
Ipsilateral and contralteral motor cortices
69
What is the inferior dividon of the facial motor nucleus connected to?
Contralateral cortex only
70
Where does the motor root of the facial nerve emerge?
Angle between the lower pons and the cerebellum - cerebellopontine angle
71
Where does the facial nerve enter the temporal bone and what accomponies it?
internal acoustic meatus, with VIII and labyrinthe artery
72
How can an accoustic neuroma affect the facial nerve?
- Benign tumour in VIII
- Both VIII and VII pass through small acoustic meatus
- Compresses facial nerve
73
What is the labyrinthe artery a branch of?
Basillar or anterior inferior cerebellar
74
What is at the bottom of the internal acoustic meatus?
Opening of the facial canal -facial nerve enters here
75
What is the first bend of the facial canal called and what is contained in it?
Genu - Geniculate ganglion - sensory ganglion of facial nerve
76
How mant bends are in the facial canal?
2
- Genu
-
77
What nerves come off of the facial nerve in the facial canal?
- Nerve to stapedius - dampens movement of stapius
| - Chorda tympani
78
Where does the facial nerve exit the temporal bone?
Stylomastoid foramen
79
Delivery by forceps can cause an injury to what cranial nerve?
Facial
80
The facial nerve sends branches to supply what muscles?
Occipitalis and auricular muscles
81
Describe the facial nerve plexus?
- Enters parotid gland and divides to form a plexus within (superficial to the external carotid artery and retromandibular vein)
82
How many nerves branch off of the facial nerve to supply the muscles of facial expression, posterior belly of diagastric and stylohyoid?
5
83
What are the 5 branches of the facial nerve?
- Temporal - supplies frontalis and orbicularis oculi
- Zygomatic - Orbicularis oculi (small part), upper lip muscles
- Buccal - cheek lip muscles
- Marginal mandibular - lower lip muscles,
- Cervical - goes to platisma
Two Zebras Befriended My Cat
84
Marginal mandibular branch located where?
- Inferior to mandible
- Overlies submandibular gland
- Around lymph nodes - AT RISK DURING SURGERY, saliva can dribble as mouth cannot close fully
85
What can facial nerve injury at cerebellopontine angle cause?
- Balance and hearing problems
- Ipsilateral facial muscle paralysis
- Hyperacusis (pain on loud sounds)
- Taste disturbances
- Reduced lacrimal secretion
86
What can facial nerve injury within the petrous temporal bone, depending on exact location cause?
- Redued lacrimal secretion
- Hyperacusis (pain on loud sounds)
- Taste disturbances
- Ipsilateral facial muscle paralysis
87
What can facial nerve injury distal to the stylomastoid foramen cause?
- Ipsilateral facial msucle paralysis
| - Dry eye, drooling
88
What is central facial palsy?
- Upper motor neuron lesion
| - Can raise eyebrows, cannot blow cheeks
89
What is peripheral facial palsy?
- Lower motor neuron lesion
| - Cannot raise eyebrows or blow cheeks
90
What is the cornea reflex?
- When you touch the cornea you close your eyes
- Afferent limb is trigeminal nerve (nasociliary branch)
- Efferent limb is facial nerve
91
Where is the nuclei of the glossopharyngeal nerve?
Medulla
92
What kind of fibres are located in CN IX?
Mixed - motor + sensory
93
What is the motor nucleus of the glossopharyngeal nerve?
Nucleus ambiguus (shared with 10, 11)
94
What os the sensory nucleus of the glossopharyngeal nerve?
Nucleus solitarius (shared with 7, 10)
95
Where does the tympanic branch of the Glossopharyngeal nerve go to?
- Middle ear
- Tympanic membrane
- mastoid air cells
96
What does the glossopharyngeal nerve receive sensation from?
- General sensation from middle ear, oropharynx, palatine tonsil, inferior aspect of soft palate, posterior 1/3 tongue
- General visceral sensation from carotid sinus and carotid body
- Special visceral sensation (taste) from posterior 1/3 tongue
97
What does CN IX provide motor supply to?
Stylopharyngeal muscle
98
Where are the vagus nuclei located?
Medulla
99
What is the motor nucleus of the vagus called?
Nucleus ambiguus
100
What is the sensory nucleus of the vagus called?
Nucleus solitarius
101
What does the vagus pass through after leaving the brainstem?
Jugular foramen (with IX and XI)
102
Where does the vagus receive general somatic sensation from?
- Deep auricle
| - Parts of the external acoustic meatus
103
Where does the vagus receive general visceral sensation from?
Laryngopharynx and larynx
104
Where does the vagus supply motor fibres to?
Striated muscles of the pharynx and larynx
105
Describe the gag reflex?
when root of tongue or posterior wall of oropharynx is touched - gag is stimulated
- Afferent limb - glossopharyngeal nerve
- Efferent limb is vagus
- Both nuclei are in medulla
- Defect in CN IX or X will affect swallowing and/or gag reflex
106
What kind of fibres are located within the accessory nerve?
Motor
107
What are the 2 roots of the accessory nerve?
- Spinal root: from C1-5
| - Cranial root: from nuc ambiguus
108
What does the accessory nerve enter the cranial cavity via?
Foramen magnum - joins with cranial root
109
What do both the spinal and cranial root exit the skull via?
Jugular formane as accessory nerve
110
Where does the accessory nerve cross?
The post. triangle in the investing layer of fascia, surrounded by lymph nodes
111
What does the spinal accessory supply?
Trapezius and sternoccleidomastoid
112
What is the nucleus of the hypoglossal nerve?
Hypoglossal nucleus in medulla
113
Where does the hypoglossal nerve exit the brainstem?
Anterior to olive
114
Where does the the hypoglossal nerve emerge from?
Hypoglossal (anterior condylar) canal
115
How does the hypoglossal nerve descend the neck?
Passes lateral to both the internal and external carotid arteries snd associated with a loop of Cx nerves that supply the strap muscles of the neck
116
Where does the hypoglossal nerve enter the oral cavity?
Under the tongue between mylohyoid and hypoglossus to supply all the tongue muscles except palatoglossus
117
If hypoglossal nerve is injured what is the result?
Ipsilateral tongue weakness, therefore the tongue deviates to the side of the lesion
