1. Trigeminal System

2. Useful animations: Readings:
Somatic sensory: A007
Sensory cranial: F003
Sensory cranial: F004
Somatic sensory: AN01
Somatic sensory: A006
Readings:
Principles of NS
General somatic sensory organization:
Brain stem/cranial nerve review:
Sensory nuclei : , Fig 44-6

3. Nociceptors, thermoreceptors, & itch receptors are bare nerve endings
Mechanoreceptors are encapsulated
Bare nerve
ending
Merkel’s receptor
Meissner’s
corpuscle
Pacinian
corpuscle

4. Dorsal horn
Anterolateral system:
spino-thal
spino-retic
spino-mesen

5. Components of the trigeminal system
Spinal nucleus
Caudal nucleus Pain/temp/itch
Interpolar nucleus Pain/reflexes, etc, ???
Oral nucleus Reflexes, etc, ???
Main sensory nucleus Mechanosensation
Mesencephalic nucleus Jaw proprioception
Motor nucleus Jaw muscles

6. Mesencephalic
Trigeminal
motor
Main sensory
Spinal trigeminal nuc:
oral
interpolar
caudal

7. Organization of the spinal trigeminal nucleus: caudal nucleus

8. 3 2 1 Interpolar nucleus 3 Caudal nucleus 2 1 Upper spinal cord
Ophthalmic division
Maxillary division
Mandibular division
7, 9, & 10 3 C2 2 1 C2
Interpolar nucleus 3
Caudal nucleus 2 1 C2
Upper spinal cord

9. Input: Small-diameter fibers
Marginal zone
Substantia gelatinosa
Spinal trigeminal
tract
Caudal nucleus
Output:
Marginal zone-->Thalamus, midbrain
Substantia gelatinosa-->interneurons

10. Spinal trigeminal
tract
Caudal nucleus
Anterolateral
system

11. Main sensory Anterolateral/ trigeminothal Trigeminal motor
lemniscus
Medial
Main sensory
Anterolateral/
trigeminothal
Trigeminal
motor
Medial/ trigeminal
lemniscus

12. Mesencephalic
Nucleus &tract

13. Mesencephalic
Nucleus &tract

14. Somatic Sensory Thalamus
Medial dorsal
Ventral posterior (VMpo)
Ventral posterior medial-VPM (trigem)
Ventral posterior lateral-VPL (spinal)
Touch
Pain

17. Anterolateral and Trigeminal Systems
Ventral posterior-->Postcentral gyrus •localization

18. Anterolateral System
Ventral medial post-->Insular •behavioral & •autonomic responses
•“Limbic”
Amygdala

19. Anterolateral and Trigeminal Systems
Medial dorsal-->Cingulate gyrus •emotional (-valence…) •“Limbic”

20. Pain suppression path - Limbic cortex Periaqueductal gray matter
Raphe nuclei (5-HT) -
Caudal
nucleus

21. Trigeminal System Separate components for pain and touch
Brain stem nuclei:
Caudal nucleus (pain)
Interpolar nucleus (caudal part for pain-mouth)
Oral nucleus (???)
Main sensory nucleus
3 Separate thalamic pain nuclei & 1 for touch:
Pain (VPM, VMpo, MD)
Touch (VPM)
3 Separate cortical representations:
Postcentral gyrus (localization)
Insular (important for pain)
Cingulate (emotions, esp. for pain)
Pain suppression system
PAG-->Raphe nuclei (5-HT)-->Caudal nucleus