CN's V and VII Flashcards
Where does CN V exit the brainstem?
-Middle/lateral pons
Where does CN VII exit the brainstem?
-Cerebellar-pontine angle
CN V:
- Axon type(s)
- CNS origin or termination
- Peripheral origin or termination
- Somatic sensory
- Spinal and main sensory nuclei, Mesencephalic nucleus
- Skin and deep tissues of head, dura. Muscle spindles and other mechanoreceptors
- Brachial motor
- Trigeminal motor nucleus
- Muscles of mastication and 2 tensor muscles
What are the 3 segments of the spinal trigeminal nucleus and their boundaries?
- Oral nucleus: From main sensory nucelus to pontomedullary junction
- Interpolar nucleus: From pontomedullary junction to obey
- Caudal nucleus: From obex to spinal cord
What does Pars Oralis receive input from?
-Intraoral and perioral structures
What is Pars interpolaris proper involved in?
-Activation of trigemino-autonomic reflexes
What fibers target Pars Caudalis?
- Those mediating pain, crude touch, temp.
- Superficial structures like oral cavity and teeth
- Deep structures like jaw muscles and TMJ
- Convergence may be basis for referred pain
What is the function of the Spinal Mesencephalic nucleus?
-Proprioception for jaw muscles
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
What is the somatotopic organization of the Pars Caudalis?
-“Onion Peel” organization- Rostral (oral) to caudal (peripheral face)
- V3: Dorsal V2: Middle V1: Ventral
- Fibers from center of face end near obey
- Fibers from back of face end in upper cervical cord
Describe the onion skin distribution of sensory loss.
-The more caudal the spinal trigeminal injury, the larger the area around the mouth that is spared of sensory loss
What is a syrinx?
-A cavity that develops in the spinal cord and extends into the brainstem. It destroys pain and temperature out laterally (in circle)
What types of sensory fibers are found in the pulp?
-70-80% are A-delta (fast pain, thermal) and C (slow pain, itch, touch)
- 20-30% are A-beta (spindle, touch, & pressure)
- From inferior alveolar nerves
Where are the heaviest projections from tooth pulp fibers located?
- Trigeminal main sensory nucleus
- Pars Oralis of Trigeminal spinal nucleus
Describe Trigeminal Neuralgia.
- Brief, episodes of excruciating pain in distribution of one (can be more, rare) division of trigeminal nerve.
- No sensory trouble between attacks
- Often a tactile stimulus triggers the attack
- Due to trigeminal compression of vessel, tumor, etc.
What is the result in Trigeminal neuralgia if they cut nerve root or introduce a lesion in trigeminal ganglion?
-Loss of all tactile and pain sensation
What is the result in Trigeminal neuralgia if they section spinal trigeminal tract slightly caudal to obey (remove afferents to caudal nucleus)?
- Tractile sensation is intact (main sensory nucleus)
- Abolishes pain sensation over half of the face
- High mortality rate: compromise medullary cardiovascular and respiratory centers
Branches of what artery are most frequently involved in cases of Trigeminal neuralgia that are due to vascular cause?
- Superior cerebellar artery
* Can slide a teflon between the nerve and artery to allow separation
Select the true statement.
A) Trigeminal neuralgia cases due to vascular causes are often attributed to branches of the posterior cerebellar artery
B) Trigeminal neuralgia attacks are often precipitated by a tactile stimulus
C) Trigeminal neuralgia patients experience severe pain between attacks
D) The somatotopic arrangement of fibers entering the main trigeminal sensory nucleus lead to the onion-skin pattern of sensory loss
E) None of the above are true
B
Where do the fibers from trigeminal mesencephalic nucleus (cell bodies) terminate and what do they sense?
- Terminate in either:
- Trigeminal motor nucleus- jaw jerk reflex
- Supratrigeminal nucleus- chewing movements
-Sense proprioception; spindles in mastication muscles, mechanoreceptors in gums, teeth and hard palate (controls occlusal vertical dimension-distance between mandible and maxilla)
Where are the receptors for the Trigeminal mesencephalic nucleus?
- Neuromuscular spindles of mastication mm.
- Pressure/tension receptors in periodontal ligaments
Where do the cell bodies for the Trigeminal Mesencephalic nucleus originate?
- Unipolar cell bodies (pseudo unipolar neurons)
- Trigeminal mesencephalic nucelus
Where are the mesencephalic, main sensory, and motor nucleus of the Trigeminal nerve located?
-Midpons
Where does the Spinal trigeminal nucleus span from?
-From pons-medullary junction to the brain stem
