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Neuro Exam 2 > Trigeminal Pathways > Flashcards

Trigeminal Pathways Flashcards

1
Q

Primary afferents associated with trigeminothalamic pathways extend from cell bodies in the ____ ganglion in 3 divisions: ___, ___, and ____

A

Trigeminal (semilunar); V1 ophthalmic, V2 maxillary, V3 mandibular

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2
Q

The trigeminal n. attaches to the brainstem as 2 adjacent roots on the ventrolateral aspect of the ______. The two roots include the larger ______ root and the smaller ______ root

A

Pons; sensory; motor

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3
Q

Each trigeminal division has somatotopic arrangement with rostral-caudal distribution. Fibers representing areas near the center of the face end near the ______, while fibers representing areas toward the back of the head end in the ___________

A

Obex; upper cervical cord

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4
Q

Trigeminal fibers ending in the cervical cord overlap spinal fibers that represent adjacent areas of skin. Thi leads to characteristic pattern of sensory loss when spinal trigeminal tract is damaged —> onion skin distribution. What is the difference between a more caudal lesion and a more rostral lesion in terms of sensory loss?

A

The more caudal the lesion, the larger the area around the mouth that is spared from sensory loss

The more rostral the lesion (into brainstem), increased degrees of sensory loss starting at the back of the head and converging on the mouth

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5
Q

4 trigeminal nuclei form a continuous cell column that extends from the ______ junction to the rostral levels of the mesencephalon/midbrain

A

Spinomedullary

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6
Q

What are the 4 nuclei associated with the trigeminothalamic pathway?

A

3 sensory:
Main sensory nucleus (msT)
Spinal nucleus
Mesencephalic nucleus (mes)

1 motor:
Trigeminal motor nucleus (mT)

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7
Q

The ______ trigeminal nucleus forms an enlargement in the midpons and is slightly lateral to the motor nucleus

A

Main sensory

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8
Q

Modality of main sensory nucleus

A

Termination point of fibers conveying touch and pressure — relays discriminative tactile info from head to ventral posteromedial nucleus (VPM) of thalamus

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9
Q

2 divisions of main sensory trigeminal nucleus and their functions

A

Dorsomedial division = afferent info from oral cavity

Ventrolateral division = afferent info from V1,V2,V3

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10
Q

The dosomedial division of the main sensory trigeminal nucleus projects to IPSILATERAL VPM via ________________ tract and ascends lateral to periaqueductal gray

A

Posterior dorsal trigeminothalamic tract (aka dorsal central trigeminal tract)

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11
Q

The ventromedial division of the main sensory nucleus projects to the CONTRALATERAL VPM via ___________ and will be joined by fibers from spinal nucleus of CN V

A

Trigeminal lemniscus (anterior trigeminothalamic tract)

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12
Q

The ventrolateral division of the main sensory trigeminal nucleus has somatotopic representation of afferents. How does this apply to V1 vs. V2 vs. V3?

A

V1 = anterior

V2 = sandwiched between

V3 = posterior

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13
Q

The main sensory trigeminal nucleus terminates somatotopically in the VPM. How does this apply to the oral cavity vs. external face?

A

Oral cavity = medially

External face = laterally

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14
Q

Tertiary axons of the main sensory trigeminal nucleus project from the VPM via posterior limb of _____ _____ to the primary somatosensory cortex.

A moderate amount of secondary neurons project to the _____ ____ of cerebellum via the ____________

A

Internal capsule

Anterior vermis; superior cerebellar peduncle

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15
Q

The _____ trigeminal nucleus extends caudally (descends) from its level

A

Spinal

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16
Q

Modality of spinal trigeminal nucleus

A

Termination point for fibers carrying pain and temperature

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17
Q

Primary afferent fibers associated with the spinal trigeminal nucleus descend as they enter the pons, joining the ________ tract, positioned lateral to the nucleus.

A

Spinal trigeminal

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18
Q

The spinal trigeminal tract is the descending tract of CN V. This becomes continuous with ______ tract in the upper cervical cord

Both the nucleus and the tract etend caudally to above the ____ cervical segment

A

Lissaur’s; 3rd

19
Q

3 regions of the spinal trigeminal nucleus

A

Pars/subnucleus caudalis
Pars/subnucleus interpolaris
Pars/subnucleus oralis

20
Q

The pars caudalis region of the spinal trigeminal nucleus is the most caudal part and extends from the spinal cord to the obex. It represents different parts of the ipsilateral _______.

The ____ division is the most posterior, while the _____ division is the most anterior, and the _____ division is in between. This arrangement allows for smooth transition of spinal levels processing cutaneous info originating at the back of the head with brainstem levels processing similar cutaneous info from teh face

A

Face

Mandibular; ophthalmic; maxillary

21
Q

Second-order neurons from the caudal nucleus (region of spinal trigeminal nucleus) decussate and ascend in ___________ tract. They terminate in the contralateral ______ of the thalamus.

Tertiary axons extend in posterior limb of internal capsule and proceed to the ________

A

Anterior trigeminothalamic (trigeminal lemniscus); VPM

Primary somatosensory cortex

22
Q

The pars/subnucleus interpolaris region of the spinal trigeminal nucleus is the middle region, located in the rostral medulla and extending to the level of the obex. Where does it receive info from in comparison with the pars oralis?

A

Pars interpolaris receives info from peripheral region of face

Pars oralis receives tactile info from central region of face

23
Q

The pars oralis region of the spinal trigeminal nucleus is the most rostral part, extending from the ______ nucleus to the pontomedullary junction

A

Main sensory

24
Q

Both the pars oralis and interpolaris are heavily involved in functions homologous to somatic functions of the SC. They project fibers to the cerebellum through the __________ ; as well as carry tactile info and project to the contralateral ______

A

Inferior cerebellar peduncle; VPM

25
Q

Which trigeminal nucleus extends rostrally all the way to the midbrain?

A

Mesencephalic nucleus

26
Q

Modality of mesencephalic trigeminal nucleus

A

Proprioceptive afferents from muscles of mastication and TMJ

27
Q

The mesencephalic trigeminal nucleus projects to the _____ nucleus and _____ nucleus via anterior/posterior trigeminothalamic tract

A

Main sensory; spinal

28
Q

What information is relayed by the mesencephalic nucleus via spinal nucleus (pars interpolaris)?

A

Proprioceptive input from the jaw related to chewing/jaw placement

this is done by the inferior cerebellar peduncle (restiform body)

29
Q

Some axons of the mesencephalic nucleus terminate in the ______ nucleus which forms the circuit of the jaw-jerk reflex

A

Trigeminal motor

30
Q

Where is the trigeminal motor nucleus located?

A

In midpons, adjacent to the main sensory nucleus; at the level of attachment of trigeminal nerve to brainstem

31
Q

The trigeminal motor nucleus innervates muscles associated with what PA?

A

PA1 = muscles of mastication as well as tensor tympani, tensor palatini, mylohyoid, and anterior belly digastric

32
Q

What are the 2 primary trigeminal reflexes?

A

Jaw-jerk reflex

Corneal reflex

33
Q

What is the jaw jerk reflex

A

Stretching the masseter (downward tap on chin) causes it to contract bilaterally

34
Q

Neuronal path of jaw jerk reflex

A

Afferent limb is mesencephalic trigeminal neuron whose peripheral process innervates a masseter muscle spindle and whose central process synapses on a trigeminal motor neuron (efferent limb)

35
Q

The amplitude of the jaw jerk reflex is usually minor, but is enhanced after damage to _____

A

UMN

36
Q

What is the corneal reflex

A

Eyes blink in response to stimulus of touching cornea

37
Q

Neuronal path of corneal reflex

A

Afferent limb originates from pain/touch receptors in cornea

Cell bodies in trigeminal ganglion, fibers travel with V1 —> terminate in ipsilateral spinal trigeminal nucleus

Trigeminothalamic fibers send collaterals bilaterally into the facial motor nucleus (efferent limb)

38
Q

Effects of unilateral lesion to trigeminal n.

A

Anesthesia and loss of general sensation in trigeminal dermatomes

Loss of jaw jerk reflex

Atrophy of muscles of mastication

Loss of ipsilateral and consensual corneal reflex

39
Q

Brainstem lesions in the upper medulla may destroy the primary fibers in the spinal trigeminal tract (descending tract of V), and secondary fibers in the spinal lemniscus lead to what condition?

A

Alternating analgesia

40
Q

Effects of alternating analgesia

A

Patients demonstrate ipsilateral hemianalgesia of the face and contralateral hemianalgesia of the body

41
Q

Alternating trigeminal hemiplegia results in unilateral destruction of the _____ n. And CST in the pons. Ipsilateral trigeminal anesthesia and paralysis and contralateral spastic hemiplegia

A

Trigeminal

42
Q

Lateral medullary syndrome occurs due to lesions of _____ a., which supplies the territory of anterolateral system AND spinal trigeminal nucleus/tract

A

Posterior inferior cerebellar a.

43
Q

Signs/symptoms of lateral medullary syndrome

A

Contralateral loss of pain (hemianalgesia) and temperature (hemithermoanesthesia)over the body with ipsilateral loss of these modalities over the face

44
Q

What is tic douloureux

A

Trigeminal neuralgia: severe episodic pain restricted to peripheral distribution of maxillary or mandibular division ipsilaterally

Further characterized by presence of trigger zones which produce ipsilateral stabbing pain with even gentle stimulation

Etiology unknown, likely vascular compression of trigeminal n. or presence of microneuromas

Neuro Exam 2 (21 decks)

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