Trigeminal System (6/30/15) Flashcards
What is Chemesthesis?
Trigeminal fibers can be activated by some chemical stimuli including spices.
What is Stereognosis?
the 3-dimensionality of objects in the mouth.
What is flavor?
taste, olfaction and texture.
Describe the 3 main branches of the Trigeminal nerve…
- Ophthalmic = sensory only
- Maxillary = sensory only
- Mandibular = sensory and motor!
*There are 16 major nerve branches and 53 named branches.
The cell bodies of the trigeminal nerve located in the ______.
Trigeminal ganglion (gassenrian/semilunar)
After entering the brain at the level of the pons the fibers bifurcate into _____ and _______ branches.
Ascending and descending branches.
Ascending branches end in the ____ and function primarily as ______.
Principal nucleus
Light touch.
Descending branches end in the ______ and has 3 divisions called____, _____ and _____.
Spinal trigeminal nucleus
Nucleus Oralis = light touch
Nucleus interpolaris = temp perception
Nucleus Caudalis = pain perception
The somatopic representation of the head and neck is organized within the _____, ______ and _______.
Sub nucleus of the brainstem, the thalamus and in the parietal lobe.
The face is represented in the _______ primary somatosensory cortex.
Lateral
How are peripheral nerves classified?
Based on size, conduction velocity, threshold and modality (what they respond to)
A- Beta (Muscle type? Threshold? Modality?)
Muscle type = 1 and 2
Threshold = Low
Modality = Touch and Proprioceptive
A- Delta ( Muscle Type? Threshold? Modality?)
Muscle type = 3
Threshold = high
Modality = Touch, Temp, Chemesthesis and Sharp pain
C-Fiber (Muscle Type? Threshold? Modality?)
Muscle Type = 4
Threshold = Highest
Modality = Temp, Chemesthesis and Dull/burning pain
What are the 4 types of mechanoreceptors?
Rapid adapting mechanoreceptors
Slow adapting Mechanoreceptors
* small and large receptive fields for each
How does transduction occur for Mechanoreceptors?
deformation or stretch of the axon membrane that opens Na channels, thereby depolarizing the axon and causing AP’s.
Mechanical transduction can also occur through _______ .
Transient Receptor Potential Channels (Piezzo 1 and 2)
Miessner corpuscle?
RA Light touch/spatial discrimination
Merkel Receptor?
SA I Pressure
Ruffini Corpuscle?
SA II Skin stretch
Pacinian Corpuscle?
RA II Vibration
The Response properties of mechanoreceptors are influenced by what 3 sources?
- The degree of mylenation
- Location of the receptor (Superficial or deep)
- The structure of the ending (Encapsulation)
Pacinian corpuscles respond to ___ and ____.
Stimuli start and cessation
What are Von Frey hairs?
Monofilaments used to measure (in grams) touch thresholds.
The closer you get to the midline of the face…..
the lower the threshold for 2 point touch discrimination (it gets better)
Oral have different anatomical receptor types than are found in the hand. T or F?
True. There are no RA II (Pacinian) receptors in the face et many RA I, SA I and II.
What is Microneurography?
Technique used to record nerve impulses.
What are the most common receptors in the tongue (Lingual branch of mandibular nerve)?
Coiled nerve endings (Krause bulbs) look similar to meissners corpuscles in the hand.
At the tip of the tongue, the receptive fields are ______.
Small
What are some origins of trigeminal dysfunction?
- Oral and facial trauma
- Complete dentures with loss of underlying tissue
- infectious diseases
- dental and surgical procedures, tooth extraction and osteotomy
TMJ Receptors help mediate _____.
Interdental sensation
What is the innervation of TMJ?
- auriculotemporal
- master and posterior deep temporal branch of trigeminal nerve.
Where is the innervation most dense in the TMJ?
Posterior and Lateral position of the capsule.
____ teeth are more sensitive.
Anterior
What is the innervation of the PDL’s?
branches of superior and inferior alveolar nerves.
* A very different type of ending is found in the PDL compared to the tongue mostly the UNENCAPSULATED RUFFINI TYPE ENDINGS.
______ is relatively superficial in the PDL compared to the _____.
Trigeminal Ganglion Mesencephalic nucleus (More innervation at apex)
When force is directed to the tooth from a _____ direction the response is largest.
distal
As a stimulus is applied more rapidly, the response latency is ______.
Shorter.
sub nucleus oralis projects to ______ to produce a __________.
Motor trigeminal nucleus to produces a jaw opending reflex via nat. digastric muscle.
_______ projections can cause salivary secretions.
Mesencephalic trigeminal nucleus
Studies indicate that both the ____ and _____ contribute to the interdental sensitivity.
PDL and TMJ
In reguards to temp, there is a ____ variation for warmth and ____ variation for cold.
Wide variation for warmth
Less variation for cold ( usually perceived more intense than warmth)
There are ____ subfamilies of Transient Receptor potential channels. comprised of _____ transmembrane domains with a cation channel between ____ and ___ domains.
8 sub families
6 domains
between 5th and 6th domains
TRPV1
temp >42 (Capsaicin and ethanol)
TRPV2
temp >52
TRPV3
temp 34-38 (camphor)
TRPV4
temp 27-34
TRPM8
Temp
TRPA1
Temp
