Neuroanatomy Cranial Neves V and VII Flashcards
The facial nerve makes up how many roots in the brainstem?
2
The facial nerve proper consists of what types of fibers?
special visceral efferent (SVE)
Nervus intermedius of VII contains what types of fibers?
GVE and sensory fibers
What type of facial nerve fibers control the muscles of facial expression?
special visceral efferent (SVE)
The superior salivary nucleus which includes the submandibular ganglion and the pterygopalatine ganglion are made up of what type of fibers?
GVE (general visceral efferent)
What type of fibers innervate the skin of the ear?
general somatic afferent (GSA) from VII (from the trigeminal spinal nucleus)
What types of fibers innervate the anterior 2/3 of the tongue?
special visceral afferent (SVA) from VII originating in the solitary nucleus
What types of fibers innervate the palatine tonsil?
general visceral afferent (GVA) from VII originating in the solitary nucleus
Fibers of the facial nerve exit the skull through which foramen?
stylomastoid foramen
Through which gland do facial nerve fibers pass?
parotid gland
Which branch of the facial nerve innervates the external ear?
posterior auricular branch
What is the parasympathetic component of the facial nerve?
nervus intermedius
What are the three parasympathetic nervus intermedius branches?
1) superior salivatory nucleus
2) greater petrosal nerve (pterygopalatine ganglion)
3) chorda tympani nerve (to submandibular ganglion)
Which fibers control the stapedius muscle?
SVE of VII (special visceral efferent)
What types of fibers control lacrimation?
general visceral efferent (GVE) fibers of VII
Which nerve is responsible for Bell’s Palsy?
VII lesion
Do one or both of the facial nerve components pass through the facial canal?
both
Do all fibers of VII exit the stylomastoid foramen together?
no, some of them branch off before the foramen
What three facial nerve branches branch off before the majority of the nerve exits via the stylomastoid formen?
1) stapedial nerve
2) branch to pterygopalatine ganglion
3) chorda tympani nerve
The chorda tympani nerve branches into two branches. What are they?
1) GVE to salivary glands
2) SVA from tongue
What is the cause of the crocodile tears?
parasympathetic fibers to submandibular ganglion have been re-routed to pterygopalatine ganglion
What happens to the person during a VII supranuclear lesion?
there is paralysis of muscles of facial expression below the level of the eye on the OPPOSITE side of the lesion
What is hyperalgesia?
noxious stimulus that evokes pain sensation greater than normal
What is allodynia?
non-noxious stimulus that evokes pain sensation
Periphreal sensitization is a result of the stimulation of what type of nerve endings?
afferent
What does repeated periphreal stimulation result in?
autosentisitzation (a form of hyperalgesia)
What are sensitizing agents for periphreal sensitization?
1) bradykinin
2) norepinephrine
3) prostaglandins
4) serotonin
Is periphreal sensitization reversible?
yes, quickly
Intense and prolonged stimulation of nociceptive fibers can result in what?
1) modification of periphreal receptor (due to increased gene expression) resulting in:
- enhanced receptor sensitivity
- increased number of receptor sites
Intense and prolonged stimulation of nociceptive fibers can result in what?
1) enhanced receptor sensitivity
2) increased number of receptor sites
In what part of the midbrain does central sensitization take place?
posterior horn/trigeminal spinal nucleus
Enhanced activity of C (pain) fibers results in what two things?
1) increased sensitivity of glutamate receptors
2) suppressed activity of inhibitory interneurons
What happens to microglia during various activities?
their morphology changes
The resting state of microglial cells is also known as what?
the surveillance state
The activated state of microglial cells is also known as what?
enhanced response state (enlarged, amoeboid configuration)
How many contacts per hour do microglial cells make and for how long do they persist?
1 contact per hour and for 5 minutes
Astrocytes interact between neuron and what?
nearby vascular supply
Astrocytes recycle neurotransmitters including what?
glutamate
What are the two states of astrocte cells
1) active (normal)
2) reactive (during a state of pain hypersensitivity)
Astrocytes release factors that do what two things?
1) enhance synaptic activity
2) promote microglia into “enhanced response state”
What is the main promoter factor of periphreal inflammation?
ATP
What type of nerve cell releases inflammatory cytokines which activate neurons within the spinal cord dorsal horn/trigeminal spinal nucleus
microglial cells
If periphreal inflammatory situation resolves, the microglia enhanced response state returns to its what?
resting state
During chronic neuropathic pain, _____ remain in an _____ _____ _____ that continue to release inflammatory cytokines
microglia, enhanced response state
What process is responsible for the continuing, persistent pain of neuropathic pain?
positive feedback from microglia
Are the borders between trigeminal innervation regions sharp or overlapped?
sharp
Can borders between trigeminal innervation regions vary between individuals?
yes
What percentage of fibers in the trigeminal nerve are C fibers?
2/3
From what pharyngeal arch are the muscles of mastication derived?
arch I
What type of nerve fibers are the trigeminal motor nerves?
special visceral efferent (SVE)
In what area does the trigeminal motor nucleus lie?
dorsolateral pontine tegmentum
What is responsible for the rhythmic actions of the motor neurons?
the reticular formation
What is larger; the motor root or the sensory root of the trigeminal nerve?
sensory
What is easier to determine; jaw opening strength or jaw closing strength?
closing
What types of fibers serve neuromuscular spindles of mastication muscles?
GSAp (general somatic afferent proprioceptive) fibers
What types of fibers are involved with pressure/tension receptors in periodontal ligaments?
GSAp
What is the cell body of origin for CN V proprioceptive fibers?
trigeminal mesencephalic nucleus
Where do the CN V proprioceptive fibers project to?
trigeminal spinal nucleus and supratrigeminal nucleus
What is an imporant role of CN V proprioceptive fibers relating to occlusion?
they control the distance between the madible and the maxilla (occlusal vertical dimension)
Where is the trigeminal mesencephalic nucleus found?
rostral pons and mesencephalon adjacent to the ventricle
What types of cells are present in the mesencephalic nucleus?
unipolar cells of neural crest origin
What is the role of the mesencephalic nucleus?
proprioception of the face (GSAp)
What type of fibers are associated with the jaw-jerk reflex?
GSAp (neuromuscular spindle, trigeminal mesencephalic nucleus, trigeminal motor nucleus)
SVE (trigeminal motor nucleus, muscles of mastication)
Sensation of the skin of face, the oronasal mucous membranes, the teeth, and the dura mater are what types of fibers?
CN V GSAe (general somatic afferent exteroceptive) sensations
What types of sensations do GSAe (extroceptive) fibers pick up?
pain, crude touch, temperature
What are the three parts of the trigeminal spinal nucleus?
1) pars oralis
2) pars interpolaris
3) pars caudalis
What types of pain are transmitted via the GSAe spinal nucleus?
fast pain and slow pain
Which 4 cranial nerves are transmitted via the trigeminal spinal nucleus?
V, VII, IX, X
What percentage of tooth pulp fibers are A-delta and C fibers?
70-80%
What percentage of tooth pulp fibers are A-beta fibers?
10-30%
Where do the majority of tooth pulp fibers project to?
trigeminal principal sensory nucleus
Which of the three trigeminal spinal nuclei has the heaviest and least heavy projection?
heaviest: pars oralis
middle: pars interpolaris
least: pars caudalis
____ receives input from intraoral and perioral structures
pars oralis of trigeminal spinal nucleus
Where is the pars caudalis of the trigeminal spinal nucleus found?
medullary posterior horn (MPH)
_____ of the trigeminal spinal nucleus contains excitatory and inhibitory interneurons and receives raphe spinal tract fibers (serotonin)
substantia gelatinosa
Pars caudalis of the trigeminal spinal nucleus receives afferents from cranial nerves: (3)
1) VII
2) IX
3) X
all of the above are from the ear
The pars caudalis of the trigeminal spinal nucleus are targets of what types of fibers?
A-delta and C fibers
Fibers from superficial structures including oral cavity and TMJ are sent where?
to the pars caudalis of the trigeminal spinal nucleus
What 4 areas of the midbrain contain estrogen receptors?
1) trigeminal spinal nucleus
2) parabrachial nucleus
3) periaqueductal gray
4) hypothalamus
High estrogen levels and stress increase activity in _____ caudalis laminae in response to pain
trigeminal spinal nucleus
_____ normally dampens pain-induce activity in trigeminal spinal nucleus caudalis
GABA
_____-ergic activity is suppressed by high estrogen levels
GABA
Oculo-cardiac reflex, nasal mucosa, face diving reflex, needle insertion into trigeminal, TMJ surgery are all examples of what?
trigeminocardiac reflex
Trigeminocardiac reflex results in what?
bradycardia (increased vagal tone) of the solitary nucleus and nucleus ambiguus, apnea, arterial hypotension, & gastric hypermobility
What type of pain is associated with trigeminal neuralgia?
excruciating, lancing pain
Is the pain of trigeminal neuralgia usually unilateral or bilateral?
unilateral
What divisions of the face are affected by trigeminal neuralgia?
mandibular (Viii) and opthalmic (Vi)
What nucleus is responsible for two-point discrimination as well as vibratory sense?
trigeminal principal sensory nucleus
Where do the two ascending trigeminal pathways terminate?
ventral posteriomedial nucleus of the thalamus (VPM)
Which eye closes during a direct corneal reflex? During a consensual?
direct: ipsilateral
consensual: contralateral