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Flashcards in CN V & VII Deck (54)
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Select the correct pair.
A) Trochlear nerve: Exits brainstem posteriorly
B) Oculomotor nerve: Superior oblique muscle
C) Abducens nerve: Inferior oblique
D) Lateral rectus: Eye adduction
E) Inferior rectus: Eye elevation

A) Trochlear nerve: Exits brainstem posteriorly


Select the correct statement.
A) Oculomotor nerve injury results in a mild deficit of eye movement
B) Trochlear nerve injury results in a large deficit of eye movement
C) Abducens injury results in medial strabismus
D) Oculomotor nerve injury results in a constricted pupil due to interruption of sympathetic fibers

C) Abducens injury results in medial strabismus


Select the correct statement about the pupillary reflex.
A) Efferent limb is the oculomotor nerve
B) Afferent limb is retina ganglion cell fibers in cranial nerve II
C) Input from cranial nerve II is sent to the Edinger Westphal nucleus bilaterally
D) Postganglionic fibers from the ciliary ganglion innervate the iris and supply the sphincter muscle of the pupil
E) All the above are true

E) All the above are true


Accommodation includes:
A) Contraction of the ciliary muscle to allow the lens to thicken centrally
B) Convergence of eyes by slight increase in medial rectus muscle tone bilaterally
C) Contraction of sphincter pupillae to constrict pupils
D) All the above are part of accommodation

D) All the above are part of accommodation


What is the main general sensory nerve for the head?



CN V transmits tactile, proprioceptive, pain and temperature from ...

head to cortex, cerebellum, reticular formation


What are the 3 divisions of CN V?

1) Ophthalmic division (Vi), (V1)
- Upper face
- Sensory only
2) Maxillary division (Vii), (V2)
- Middle face
- Sensory only
3) Mandibular division (Viii), (V3)
- Lower face
- Sensory and Motor

*Sharp borders between divisions; varies among individuals


What are the trigeminal nuclei?

1) Midbrain - Trigeminal mesencephalic nucleus
2) Rostral Pons - Trigeminal principal
sensory nucleus, Trigeminal motor nucleus
3) Rostral Pons/Medulla - Trigeminal spinal


What do Trigeminal Ascending Projections run from and to?

From: Trigeminal spinal nucleus
Contralateral projection to:
-Ventral posteromedial nucleus of thalamus (VPM)
-Internal capsule
-Postcentral gyrus parietal lobe (Brodmann’s Areas 3,1,2

From: Main trigeminal sensory nucleus
Bilateral projection to:
-Ventral posteromedial nucleus of thalamus (VPM)
-Internal capsule
- Postcentral gyrus parietal lobe (Brodmann’s Areas 3,1,2)


What are the Trigeminal Nerve Functional Components?

- Sensory afferent - Region served:
1) Face
2) Oral cavity, teeth
3) Meninges
- Cell bodies: Trigeminal ganglion
Terminates in: Main trigeminal sensory nucleus
Senses: Discriminative touch and vibration


True or false: The sensory nuclei of CN V form a column of cells that is almost continuous through the brainstem.



True or false: The main sensory nucleus of CN V is at about mid-pons and is a bit lateral to the trigeminal motor nucleus



The spinal nucleus of CN V extends caudally into the ____



Mesencephalic nucleus extends into midbrain. It is rather thin and is accompanied by the mesencephalic trigeminal tract. The mesencephalic nucleus is odd in that is contains pseudounipolar neurons as seen in dorsal root ganglia of the cord, so it is as if a bit of a ganglion somehow got incorporated into the CNS. Myelinated processes from these pseudounipolar neurons form the mesencephalic tract. The peripheral processes go to ...

spindles of muscles of mastication, mechanoreceptors of teeth, gums and hard palate.


What does main sensory nucleus of V sense?

Discriminative tactile (face and oral cavity) and some proprioception (jaw position)


What are the two ascending pathways of V main sensory nucleus?

Crossed pathway joins medial lemniscus on its way to VPL
Uncrossed, dorsal trigeminal tract, inside of mouth represented to VPM (ends near uncrossed taste pathway)


True or false: V main sensory nucleus is a homologue of posterior column nuclei



What are the functions of the Spinal trigeminal nucleus?

Nucleus blends with posterior horn of cord and divided into three segments based on histology

Functional differences between three parts is incompletely understood but still some functional correlations are possible


What are the three parts of the Spinal trigeminal nucleus?

1) Pars Oralis: Receives input from intraoral and perioral structures
2) Pars interpolaris proper
Activation of trigemino-autonomic reflexes
3) Caudalis-Interpolaris transition zone
Not somatotopically organized
Responds to pain stimuli from many areas served by V
May be involved in activation of pain suppression mechanisms


What fibers target Pars Caudalis?

fibers mediating:
Crude touch
Temperature sensation


What structures does Pars Caudalis supply?

-Superficial structures including oral cavity and teeth
-Deep structures including jaw muscles and TMJ
*Convergence may be basis for referred pain


Select the correct pair.
A) Main trigeminal sensory nucleus: Posterior column- medial lemniscus system for head
B) Spinal trigeminal nucleus: Pain and temperature for head
C) Spinal trigeminal tract: Contains descending fibers from cell bodies in trigeminal ganglion
D) Spinal mesencephalic nucleus: Proprioception for jaw muscles
E) All of the pairs above are correct

E) All of the pairs above are correct


Spinal trigeminal afferents descend thru ....

spinal trigeminal tract and synapse in caudal nucleus


Spinal trigeminal second order neurons sends axons across ...

midline, ascend and join spinothalamic tract, terminates in VPM


Describe Pars Caudalis?

- Laminar structure
- Blends with posterior horn of cervical cord
- Somatotopic organization
1) Inverted representation of face
2) ‘Onion Peel’ representation – rostral (oral) to caudal (peripheral face)
3) Primarily pain fibers
- Substantia gelatinosa (Lamina II)
1) Contains excitatory and inhibitory interneurons
2) Receives raphe spinal tract fibers (serotonin)
- Receives afferents from cranial nerves
1) VII, IX & X – all for area near ear


What is the Somatotopic arrangement of pain-temperature afferents in Pars Caudalis?

1) Mandibular division: dorsal
2) Ophthalamic: ventral
3) Maxillary: in between
4) Fibers representing center of face end near obex
5) Fibers representing back of the face end in upper cervical cord


What is the "Onion skin distribution of sensory loss"?

More caudal the spinal trigeminal tract injury the larger the area around the mouth that is spared of sensory loss


Clinical correlation: Tooth pulp

1) 70 – 80% of fibers are A-delta (fast pain, thermal) and C (slow pain, itch, touch)
2) 20 – 30% of fibers are A-beta (spindle, touch & pressure)
From inferior alveolar nerves, enter root canals and form plexus in pulp, predentin and dental tubules
3) Fibers project to:
Trigeminal main sensory nucleus (heaviest projection - shared)
Trigeminal spinal nucleus
A) Pars oralis (heaviest projection – shared)
B) Pars interpolaris (modest projection)
C) Pars caudalis (light projection)
Upper cervical spinal cord


Describe Trigeminal neuralgia?

- Brief, episodes of excruciating pain in distribution of one (can be more) division of the trigeminal nerve
*Mandibular division 70%
*Ophthalmic division < 5%
- No sensory trouble between attacks
- Often a tactile stimulus triggers an attack
- A number of cases due to trigeminal compression by a vessel, tumor etc.
- Often responds to medications.


What are the trigeminal neuralgia surgeries and results?

Surgical procedures include cutting nerve root, introducing a lesion in trigeminal ganglion

Result: loss of all tactile sensation not just pain to the area

- Section spinal trigeminal tract slightly caudal to obex
- Remove afferents to caudal nucleus
A) Tactile sensation is intact (main sensory nucleus)
B) Abolishes pain sensation over half of the face
- High mortality rate: Compromise medullary cardiovascular & respiratory centers