The Trigeminal System Flashcards
What is the nervous system made up of?
CNS: - brain and spinal cord
Peripheral NS: - spinal nerves and cranial nerves
What does the primary afferent nerve do?
What is trigeminal sensory nuclei?
Name the pathway of nerves:
Where does it synapse?
Primary afferent: takes info from periphery into CNS at first synapse
Trigeminal sensory nuclei: synapse with second order neurone - crosses midline and synapses in thalamus
This pathway of nerves is called the trigemino-thalmic tract
In thalamus on contralateral side, it synapses with a nerve at the somatosensory cortex
What is the peripheral trigeminal nerve made up from:
- 3 divisions: opthalmic, maxillary, mandibular
- 1 ganglion: trigeminal (or semilunar/gasserian)
- also trigeminal mesencephalic nucleus
- 2 roots: sensory, motor, both enter at pons
What are the 4 structures in the trigeminal sensory nuclear complex?
What is the main function processed at nucleus caudalis?
Damage to nucleus caudalis or trigeminal tractotomy:
- loss of ipsilateral facial pain, hot/cold
- still feel touch
Therefore, nucleus caudalis is the site for suynapses for pain, hot and cold
Function of nucleus oralis?
Nociceptive inputs to nucleus oralis especially for teeth
- ? necessary for oral and dental pain
- ? nociceptive neurones in nucleus oralis for reflexes rather than sensation
Function of main sensory nucleus?
Damage to MSN
- ipsilateral loss of funtion to face
- still feel pain, hot and cold
Experiment was carried out by small no. of pts with other CNS lesions aswell
Conclusion: MSN is probably the site for synapses for touch
What are the likely function of trigeminal sensory nuclei?
- main sensory nucleus
- nucleus caudalis
- nucleus oralis
- nucleus interpolaris
- main sensory nucleus: probable synapses for touch
- nucleus caudalis: synapses for facial pain and hot/cold, possible site for oral/dental pain
- nucleus oralis: possible site for oral/dental pain, reflexes
- nucleus interpolaris: reflexes
Functions of motor root of peripheral trigeminal nerve?
Where are the cell bodies for these functions?
Where do they synapse?
- sends signals to muscles of mastication
- efferent: takes signals from CNS to PNS
- also contains some afferents: muscle spindles and PDL mechanoreceptors
Trigeminal mesencephalic nucleus contains cell bodies for:
- jaw muscle spindle afferents
- some mechanoreceptive afferents from the PDL
Synapse in trigeminal motor nucleus