Neuro - Week 1 Flashcards
What types of Stimulus do general sensory receptors encode? (4)
1) Quality: brush, pressure, vibration, temperature, pain
2) Intensity: light stroke vs. intense pressure
3) Duration:
4) Location:
What is a Receptive Field?
Area in periphery (ex. skin) where an adequate stimulus causes a response in a neuron.
How does a sensory neuron encode intensity? (2)
Rate Code: Frequency of AP’s firing per neuron. The more action potentials firing, the higher the intensity
Spatial Summation Code: Number of neurons firing. The more neurons firing, the higher the intensity
What factors influence conduction velocity? (2)
1) AXON DIAMETER (higher = faster)
2) MYELINATION (thicker = faster)
Which fibers have the LARGEST myelin and FASTEST conduction? (2)
1) A alpha fibers: muscle spindle
2) A beta fibers: light touch, vibration, pressure
Which fibers have THIN myelin and MEDIUM conduction? (1)
A delta fibers: Nociceptors (fast pain), cooling receptors
Which fibers are UNMYELINAED and have the SLOWEST conduction? (1)
Nociceptors (slow pain) and warm receptors
What is a Remap Bundle?
a bundle of Nociceptors
What would a Compound AP from a nerve look like if there was a loss of access to a particular nerve fiber?
The magnitude of the peak corresponding to the fiber that has damage would be reduced.
What would a Compound AP from a nerve look like if there was a decrease in the conduction velocity of a fiber?
The peak corresponding to the fiber that has damage would shift to the right.
What would most likely cause a decrease in conduction velocity of a nerve?
De-myelination. Diseases that cause this include Diabetes, Herpes Zoster. and Guillian-Barre
What are the CHARACTERISTICS and PURPOSE of a SLOWLY ADAPTING response?
Characteristics: Fires throughout stimulus: Sustained, unchanging stimulus
Purpose: Pressure and the Shape of Objects
What are the CHARACTERISTICS and PURPOSE of a RAPIDLY ADAPTING response?
Characteristics: Fires only when stimulus changes: Fires at the beginning and end of stimulus
Purpose: Impact, motion of objects, on/off stimuli
What does SPATIAL RESOLUTION depend on? (2)
1) Receptive field size (smaller = more sensitive and higher spatial resolution)
2) Innervation Density
What is a 2-point discrimination threshold?
Minimum distance between two detectable stimuli
What are the characteristics of MECHANORECEPTORS? (4)
1) Very sensitive to force (low threshold)
2) Doesn’t respond to painful stmiuli
3) Silent without stimulation (doesn’t fire without stimulation)
4) Myelinated axons (fast conduction velocity)
What are 5 types of mechanoreceptors?
1) Merkel Disks
2) Meisnner’s corpuscles
3) Ruffini corpuscles
4) Pacinian Corpuscles
5) Hair follicle receptors
What are the following characteristics of MERKEL DISKS?
Type of information encoded?
Fine touch, 2 point discrimination, resolution of texture (bumpy vs smooth)
What are the following characteristics of MERKEL DISKS?
Receptive field characteristics (size, number, name)?
Several small, sensitive spots called “Touch Domes”
What are the following characteristics of MERKEL DISKS?
Location and skin level?
superficial, high density in finger tips, lips and mouth
What are the following characteristics of MERKEL DISKS?
Adaption Response?
Slowly adapting response and the number of action potentials indicates indentation force
What are the following characteristics of MERKEL DISKS?
Axon characteristics?
Myelinated, several disks are innervated by a single axon
What are the following characteristics of MEISSNER’S CORPUSCLES?
Type of information encoded?
Type of information encoded: Fine touch, 2-point discrimination, senses abrupt changes in edges, bumps, corners of objects
What are the following characteristics of MEISSNER’S CORPUSCLES?
Receptive field characteristics (size, number, name)?
single spot
What are the following characteristics of MEISSNER’S CORPUSCLES?
Location?
superficial, glabrous skin only, high density in finger tips, lips, mouth
What are the following characteristics of MEISSNER’S CORPUSCLES?
Adaption Response?
Rapidly adapting response. Number of action potentials fired indicates the number of times the skin is indented
What are the following characteristics of MEISSNER’S CORPUSCLES?
Axon characteristics?
Myelinated, terminal fiber wraps around epithelium so force is easily sensed
What are the following characteristics of RUFFINI CORPUSCLES?
Type of information encoded?
Type of information encoded: Stretch of skin, sense gravity force against skin
What are the following characteristics of RUFFINI CORPUSCLES?
Receptive field characteristics (size, number, name)?
Receptive field: Large and diffuse
What are the following characteristics of RUFFINI CORPUSCLES?
Location?
Location: superficial, Deep in the dermis
What are the following characteristics of RUFFINI CORPUSCLES?
Adaption Response?
Adaption Response: slowly adapting response to skin stretch
What are the following characteristics of RUFFINI CORPUSCLES?
Axon characteristics?
Type of information encoded: Stretch of skin, sense gravity force against skin
Axon Characteristics: Axon is myelinated, axon surrounds collagen fibrils
What are the following characteristics of PACINIAN CORPUSCLES?
Type of information encoded?
Type of information encoded: Tiny (low indentation), high frequency vibrations. Tuning fork, violin string
What are the following characteristics of PACINIAN CORPUSCLES?
Receptive field characteristics (size, number, name)?
Receptive field: Very Large, diffuse
What are the following characteristics of PACINIAN CORPUSCLES?
Location?
Location: deep in skin
What are the following characteristics of PACINIAN CORPUSCLES?
Adaption Response?
Adaption Response: Slowly Adapting response
What are the following characteristics of PACINIAN CORPUSCLES?
Axon characteristics?
Axon Characteristics: Myelinated Axon. A large fluid-filled capsule is wrapped around a bare nerve ending
What is the optimal frequency and indentation of a Pacinian Corpuscle?
Frequency: 300 hz
Indentation: close to zero
What is the optimal frequency and indentation of a Meissner’s corpuscle?
Frequency: 50 hz
Indentation: 50 microns
What are the following characteristics of a HAIR FOLLICLE RECEPTOR?
Type of information encoded?
Type of information encoded: Velocity of hair movements
What are the following characteristics of a HAIR FOLLICLE RECEPTOR?
Receptive field characteristics (size, number, name)?
Receptive field: axon wraps around base of follicle
What are the following characteristics of a HAIR FOLLICLE RECEPTOR?
Adaption Response?
Adaption Response: Rapidly adapting response
What are the following characteristics of a HAIR FOLLICLE RECEPTOR?
Axon characteristics?
Axon Characteristics: Myelinated
What are the following characteristics of a HAIR FOLLICLE RECEPTOR?
Type of information encoded?
Receptive field characteristics (size, number, name)?
Adaption Response?
Axon characteristics?
Type of information encoded: Velocity of hair movements
Receptive field: axon wraps around base of follicle
Adaption Response: Rapidly adapting response
Axon Characteristics: Myelinated
Which receptors are the best, and second best, at distinguishing spacing?
1st: Merkel disks
2nd: Meissner’s corpuscle
What is the Spatial Summation Code:
Overall picture in brain due to sum of information from the pattern of activation of different fibers.
What are the following characteristics of a COOLING receptor?
Type of information encoded?
Type of information encoded: Cooling of skin
What are the following characteristics of a COOLING receptor?
Receptive field characteristics (size, number, name)?
Receptive field: very small
What are the following characteristics of a COOLING receptor?
Location?
Location: Infrequent distribution
What are the following characteristics of a COOLING receptor?
Adaption Response?
Adaption Response: At physiological temperature, the axon fires at 1 hz continuously. When cooled, action potential frequency increases and are rapidly adapting. Speed of cooling is indicated by frequency of action potentials.
When heated, action potentials decrease in frequency.
What are the following characteristics of a COOLING receptor?
Axon characteristics?
Axon Characteristics: free nerve ending and thinly myelinated (Adelta)
What are the following characteristics of a WARMING receptor?
Type of information encoded?
Receptive field characteristics (size, number, name)?
Adaption Response?
Axon characteristics?
Type of information encoded: Warming of skin
Receptive field: very small
Adaption Response: At physiological temperature, the axon fires at 1 hz continuously. When warmed, action potential frequency increases and are rapidly adapting. Speed of warming is indicated by frequency of action potentials.
When cooled, action potentials decrease in frequency.
Axon Characteristics: free nerve ending and unmyelinated (C fiber)
What is the optimal range for a WARMING RECEPTOR?
33-42 degrees C
What are the following characteristics of a WARMING receptor?
Axon characteristics?
free nerve ending and unmyelinated (C fiber)
What are the following characteristics of a WARMING receptor?
Type of information encoded?
Type of information encoded: Warming of skin
What are the following characteristics of a WARMING receptor?
Receptive field characteristics (size, number, name)?
Receptive field: very small
What are the following characteristics of a WARMING receptor?
Adaption Response?
Adaption Response: At physiological temperature, the axon fires at 1 hz continuously. When warmed, action potential frequency increases and are rapidly adapting. Speed of warming is indicated by frequency of action potentials.
When cooled, action potentials decrease in frequency.
What are the types of Nociceptors? (2)
1) A-mechanonociceptor
2) C Polymodal Nociceptors
What are the following characteristics of a A-mechanonociceptor?
Type of information encoded?
Responds to intense force and intense heat. Causes fast pain (sharp, shootng, electrical pricking pain and easy to localize pain)
Includes pain when you stub toe, hit thumb, or and under very hot water
What are the following characteristics of a A-mechanonociceptor?
Adaption Response?
Slowly adapting response. Only responds to intense force. Frequency of action potential determines strength of force.
What are the following characteristics of a A-mechanonociceptor?
Receptor Field?
Small receptor field
What are the following characteristics of a A-mechanonociceptor?
Axon characteristics?
Free nerve endings and axon is myelinated (A-Delta fibers)
What are the following characteristics of a C Polymodal nociceptors?
Type of information encoded?
Intense force, high heat (above 45 degrees.) Also responds to chemicals (bradykinin, prostaglandins, histamine, acid)
Slow pain, long lasting, burning, aching, dull pain and it is difficult to localize.
Begins responding at less heat than A mechanoneceptors and can desensitize to high heat.
What are the following characteristics of a C Polymodal nociceptors?
Adaption response?
Slowly adapting response. Only responds to intense force. Frequency of action potential determines strength of force.
What are the following characteristics of a C Polymodal nociceptors?
Axon Characteristics?
Axon is unmyelinated (C fiber.) Free nerve endings that are accessible to inflammatory chemicals
Where are the cell bodies of the 1st neuron of the dorsal column located?
The Dorsal Root Ganglia
What type of information do the peripheral processes of the 1st neuron of the dorsal column encode?
Sensory information from mechanoreceptors
Where does the 1st neuron of the dorsal column terminate?
In dorsal column nuclei (either nucleus gracilis or nucleus cuneatus)
Where are the cell bodies of the 2nd neuron in the dorsal column? (what nucleus and what level of the CNS) (2)
In either:
1) Nucleus gracilis
or
2) Nucleus cuneatus
At the level of the caudal medulla or upper spinal cord
Which neuron of the dorsal column decussates and where does this occur?
The 2nd neuron decussates in the caudal medulla
What are the fibers that decussate in the dorsal column called?
Internal arcuate fibers
What is the medial lemniscus?
The medial lemniscus carries the 2nd neuron of the dorsal column after deccusation
Where does the 2nd neuron of the dorsal column (medial lemniscus at this point) terminate?
in the VPL (ventral posterior lateral) of the thalamus
Where are the cell bodies of the 3rd neuron of the dorsal column sensory pathway?
VPL of thalamus
Where do axons of the 3rd neuron of the sensory pathway go through?
posterior limb of internal capsule
Where does the 3rd neuron of the dorsal column sensory pathway terminate?
Terminates in the SI cortex (post-central gyrus/primary somatosensory cortex)
Which level contributes to FASCICULUS GRACILIS?
Axons from below T7 (lower limb)
Which level contributes to FASCICULUS CUNEATUS?
Axons from above T7 (upper limb)
What structure seperates fasciculus gracilis and cuneatus
Posterior Intermediate Septum
What levels of the spinal cord will have both fasciculus cuneatus and gracilis?
T7 and below (thoracic after t7, lumbar and sacral regions)
What is Posterior Cord Syndrome and what are the symptoms?
Posterior Cord Syndrome occurs usually due to some disease (herpes) that wipe out the dorsal column.
There would be a loss of light touch, pressure, vibration and proprieception from dermatomes below the level of the lesion.
What sensory defects relating to the dorsal column would be seen if there was a UNILATERAL SPINAL CORD LESION?
Loss of light touch, pressure, vibration and proprioception IPSILATERALLY and below the lesion.
What sensory defects relating to the dorsal column would be seen if there was a LARGE CENTRAL CORD LESION?
Loss of light touch, pressure, vibration and proprioception from dermatomes below the level of the lesion.
However, SACRAL regions would be spared because these neurons are located more dorsal.
How is the somatotopy of the dorsal column represented at the levels of Caudal Medulla, Rostral Medulla, and Pons
Caudal Medulla: Ipsilateral, lateral = upper limbs and trunk, medial = lower limbs
Rostral Medulla: contralateral, dorsal = upper limbs and trunk, ventral = lower limbs (“Headless hemi-man standing on pyramids”)
Pons: trigeminal n. enters at mid-pons so face is added, otherwise same as rostral medulla
What defects would result in a MEDIAL LEMNISCUS LESION?
Loss of light touch, pressure, vibration and proprioception from dermatomes below the level of the lesion on the CONTRA-LATERAL side of body
What part of the thalamus transmits fibers involving sensation from the body?
VPL (ventral posterior lateral)
What part of the thalamus transmits fibers involving sensation from the face?
VPM (ventral posterior medial)
How does the thalamus process sensory neurons from the dorsal column? (2)
1) relays them to the somatosensory cortex
2) can inhibit signals during stress
How is the somatotopy of the 3rd neuron in the thalamus represented?
Medial = face (VPM)
Lateral = body (VPL - lower limb most lateral)
What is the corona radiata?
Axons that radiate from the thalamus that fan out towards the cortex
What does a lesion in the thalamus or SI cortex result?
Loss of sensation from CONTRA-LATERAL side of body
What are the broadman areas associated with the SI cortext? (4)
3a, 3b, 1, 2
What type of information does Broadman area 3a transmit?
limb movement
What type of information does Broadman area 3b transmit?
basic tactile information (edges and texture)
What type of information does Broadman area 1 transmit?
motion and direction of movement of objects
What type of information does Broadman area 2 transmit?
limb position, shapes of objects
What pathway do sensory neurons follow starting from the thalamus?
Thalamus –> SI –> SII –> Inter-piratal sulcus (association cortex) –> Motor cortex
Where is SII?
Sylvian fissure and Insula
What would a UNIMODAL LESION of the parietal lobe result in?
agnosias (inability to recognize an object or a property of an object)
What would a MULTIMODAL LESION of the parietal result in?
contra-lateral neglect
What is Anesthesia?
Lack of all sensation
What is Analgesia?
Lack of pain
What is Athermia?
Lack of thermal sensation
What is Hypoalgesia?
Decreased sensitivity to pain
What is Hyperesthesia?
Heightened sensitivity to any stimulus
What is Paresthesia?
unpleasent, abnormal sensation: tingling, pricking, numbing, stinging, “pins and needles”
What is Pruritus?
itching
What is Hyperalgesia?
Increased pain from normally painful stimuls
What is Allodynia?
Pain from normally non-painful stimulus
What is Congenital Insensitivity to pain?
Type 1?
Type 2?
Lack of ability to feel pain. Usually results in early death from accumulated injury.
Type 1: Caused because of lack of access to a required nerve growth factor: nocceptors can’t grow
Type 2: Mutation in the gene for voltage gated channels of nocceptors: Nocceptors present but not working
What is fibromyalgia?
Trigger points throughout the body trigger bouts of intense pain. Don’t know what causes this. Usually seen in women.
What is acute pain?
Critical protective function, serves as a warning that injury should be avoided or treated
What is chronic pain?
Pain that doesn’t go away or adapt. Pain continues after complete healing. Chronic pain serves no useful purpose.
What is Nociceptive pain?
Cause:
Type of pain?
Type of fibers?
Mechanism? (2)
Cause: Inflammation of soft tissues
Type of pain: Chronic
Type of fibers: C fibers
Mechanism: Inflammatory chemicals sensitize nociceptors by lowering their threshold; they also send an increased barrage of action potentials to spinal cord
What is the treatment for Nociceptive pain? (2)
Mechanism?
Treatement: NSAIDs or opiods
Mechanism: NSAIDs block the synthesis of prosta-glandins from arachodonic acid
What chemicals make up he inflamatory response? (6)
Histamine, Bradykinin, 5-HT, Prostaglandin, ATP, H+
What is Neuropathic pain?
Cause:
Type of pain?
Symptoms?
Treatement?
Cause: direct damage to nerves in PNS or CNS (cut, compression, loss of blood or oxygen)
Types of pain: Chronic
Symptoms: Incapacitating sharp pain, burning, electrical quality, allodynia
Treatment: anti-anxiety and anti-depression drugs
What are examples of causes of Neuropathic pain? (3)
Post herpetic neuralgia after shingles infection
diabetic neuropathy
severe nerve entrapment
What type of information is conveyed by the Anterolateral systrem? (2)
Pain and temperature
What type of fibers and sensations input into the anterolatera system? (3)
A-delta fibers (fast sharp acute pain)
C-fibers (delayed chronic pain)
Thermo-receptors (non-painful warming and cooling)
Where are the cell bodies of nociceptors located?
DRG
How do nociceptors enter the spinal cord and where do they synapse?
Enter: via Dorsal lateral tract of Lissaur
Synapse: on second order neurons in the dorsal horn: Lamina 1, 2 or 5
What chemicals do first order neurons of nociceptors use to activate receptors of 2nd order neurons? (2)
Release of glutamate and substance P
What’s a major difference between where primary neurons of the anterolateral tract synapse compared to where primary neurons of the dorsal columns synapse?
Primary neurons of the anterolateral tract synapse in the spinal cord in the dorsal horns of the spinal level where they entered
Primary neurons of the dorsal column tract ascend without synapsing at the level of the spinal cord they entered and synapse in dorsal column nuclei in the caudal medulla
What is the initial path of 2nd order neurons of the anterolateral tract?
Cell bodies in the dorsal horn send axons that cross to the contralateral side within 3 segments rostral and ascend in anterolateral tracts (3 main pathways after this).
What would a lesion to the anterolateral tracts result in?
Loss of pain and temperature to areas BELOW the lesion on the CONTRALATERAL side.
Loss is complete by 2-3 spinal segments below the lesion
What are the names of 3 pathways the 2nd neuron of the anterolateral tract can take and what are their main functions?
1) Spinothalamic tract (Discrimination between pain)
2) Spinoreticular Tract (Attention, arousal, affect)
3) Spinomesencephalic tract (Endogenous pain relief)
What are some potential causes for a unilateral spinal injury? (3)
Loss of blood supply (artery compression)
Bone fragment
Disk herniation
What is Anterior cord syndrome?
Anterior spinal artery lesion can result in loss of blood supply and damage to tissue in the anterior part of the spinal cord. Most frequently affects the anterolateral tracts
What is Central cord syndrome?
Causes? (3)
Symptoms? Where does it affect?
Hole in the center of spinal cord
Causes: Syringomyelia, trauma, tumor
Symptoms: cuts crossing axons of 2nd order neurons that go into anterolateral tracts. Causes bilateral loss of pain and temp. Affects only levels of spinal cord where lesions exist.
What is Syringomeylia?
Cavity or cyst in center of spinal cord that can cause Central Cord syndrome
Where does the Spinothalamic tract terminate? (2)
2 areas in the thalamus
Ventral Posterior Lateral (VPL) Nucleus
Central Lateral Nucleus
What part of the medulla does the spinothalamic tract ascend?
Lateral
What type of sensation does the spinothalamic tract mediate?
Mediates discriminative aspects of pain and temperature senses (location, intensity, duration)
From where does the VPL of the spinothalamic tract get it’s innervation?
Pain info from the body (not neck or head)
Where do 3rd order axons of the spinothalamic tract project to after the VPL?
What role do these axons play?
Projections: Axons project to the SI cortext (areas 3b, 1, 2)
Role: Localizes where noxious stimulus on body occurred, how intense and it’s quality
Where do 3rd order axons of the spinothalamic tract project to after the Central Lateral Nucleus?
What role do these axons play?
Projections: Limbic cortex (cingulate gyrus, hippocampus, amygdala)
Role: Involved in emotional suffering during chronic pain and memory of painful events
What are the functions of the thalamus regarding pain?
1) Processing of nociceptive information (crude pain and temp sensations, emotional suffering reactions)
2) Relay information to SI cortex
What is the reticular formation?
A long column of nuclei extending from the medulla to the pons. 2nd order pain fibers from the spinoreticular tract terminate here.
Where does he spinoreticular tract terminate?
In the reticular formation in medulla and pons
What role does he spinoreticular tract play?
Mediates changes in level of attention to painful stimuli. Involved in emotional, arousal, attention, affective response to noxious stimulus. How tied into anxiety the pain is.
Where does the 2nd order neurons of the spinomesencephalic tract ascend?
Ascend with the spinothalamic tract up the lateral medulla
Where does the spinomesencephalic tract terminate?
Periaqueductal Gray Matter (PAG) in the superior collicululus of the midbrain
Where do 3rd order neurons of the spinomesencephalic tract project? (2)
What chemicals do these axons release?
Projection: Descends to spinal cord through 2 nuclei
1) Raphe nuclei in the medulla (Release Seratonin)
2) Locus ceruleus in pons (Release norepinephrin)
Axons from these nuclei descend and synapse on interneurons or spinalthalamic neurons in the spinal cord
What is the role of the Insula? (2)
1) Processes info on internal, autonomic state of body (heart races, breathing rapid, mouth dry, muscles tense, can’t seep)
2) Integrates discriminative, affective, emotional, cognitive components of pain
What would a lesion to the insular cortex cause?
Asymbolia for pain: Patients perceive stimulus as noxious, but don’t care. Emotional response to pain is inappropriate (may laugh)
What is the role of 3rd order neurons of the spinomesencephalic tract?
descending control pathway that inhibit pain signals, provides a negative feedback loop for pain
Where does morphine act in the nervous system?
Morphine activates cells in the PAG, activating descending inhibitory pathways that inhibit pain
Where does the common pathway begin for pain and temperature coming from the periphery and visceral pain?
2nd order neurons of the spinothalamic tract in the dorsal horn
Where is pain referred to for pain coming from the Diaphragm?
C3-C4
Where is pain referred to for pain coming from the Heart? Side?
T1-T4 (left)
Where is pain referred to for pain coming from the Stomach? Side?
T6-T9 (left)
Where is pain referred to for pain coming from the Gallbladder? Side?
T7-T8 (right)
Where is pain referred to for pain coming from the Duodenum?
T9-T10
Where is pain referred to for pain coming from the Appendix? Side?
T10 (right)
Where is pain referred to for pain coming from the Reproductive organs?
T10-T12
Where is pain referred to for pain coming from the Kidney/ureter?
L1-L2
Where does the trigeminal ganglia enter the brainstem?
Ventrolateral pons
Where do 1st order nuerons for FINE/DISCRIMINATIVE TOUCH from the trigeminal ganglia synapse?
Main sensory nucleus in pons (chief nucleus V)
Where do 1st order neurons for PAIN AND TEMPERATURE from the trigeminal ganglia synapse?
Spinal trigeminal nucleus - long column from pons to cervical cord
Where do 2nd order neurons from the main sensory nucleus project to?
VPM
Where do 2nd order neurons from the spinal trigeminal nucleus project to?
VPM
What is the somatatopy of the VPM
Tongue = medial
Oral Cavity = middle of VPM
Face = lateral
What is the pathway of 2nd order neurons conveying fine touch from the face?
Cell body?
Pathway?
Synapse?
Cell bodies: Chief Nucleus V
Pathway: Axons decussate and ascend via the Trigeminal Leminscus to the VPM of the thalamus
Synapse: 3rd order neurons
What is the trigeminal leminscus and what does it run with?
The trigeminal leminscus is the pathway of 2nd order neurons conveying fine touch sensation from the face/trigeminal ganglion.
It runs with the Medial Lemniscus
Where do 3rd order neurons of the trigeminal system projecting fine/discriminative touch project to?
Lateral SI cortex (near lateral fissure)
Where do axons projecting fine touch from the face decussate?
2nd order neurons of the trigeminal system coming from Chief nucleus V decussate at the level of the pons.
What is a minor pathway for crude touch coming from the face?
1st order neuron: cell body in the trigeminal ganglion send axons to the chief nucleus V where they DO NOT synapse. Axons descend via Spinal tract V and synapse on spinal nucleus V at the caudal medulla
2nd order neuron: axons decussate and ascend as the trigeminal lemniscus to VPM
What is the pathway for 1st order neurons coming from the oral cavity conveying FINE TOUCH?
Cell bodies?
Synapse?
Cell bodies: trigeminal ganglion
Synapses: on 2nd order neurons in the Chief nucleus V
What is the pathway for 2nd order neurons coming from the oral cavity conveying FINE TOUCH?
Cell bodies?
Pathway?
Synapse?
Cell bodies: Chief Nucleus V
Pathway: SOME neurons cross to the contralateral side and ascend via the Dorsal trigeminal tract, and SOME neurons ascend without crossing
Synapse: Synapses on 3rd order neurons in the VPM on both sides
What is the pathway for 1st order neurons coming from the face conveying PAIN AND TEMPERATURE?
Cell bodies?
Pathway?
Synapse?
Cell bodies: Trigeminal ganglion
Pathway: axons enter the pons project descend ipsilaterally via Spinal Trigeminal Tract V
Synapse: axons synapse all along the Trigeminal Nucleus V
What is he Trigeminal Nucleus V?
What cell bodies are there?
Location?
Cell bodies: 2nd order neurons conveying pain and temperature from the face
Location: long column from he pons to cervical cord
What is the pathway for 2nd order neurons coming from the face conveying PAIN AND TEMPERATURE?
Cell bodies?
Pathway?
Synapse?
Cell bodies: Trigeminal Nucleus V
Pathway: Axons decussate and ascend via Trigeminothalamic tract
Synapse: Terminates in VPM of thalamus
What is the Trigeminothalamic tract and what tract does it run alongside?
Contains 2nd order neurons conveying pain and temperature from the face.
Runs alongside the spinothalamic tract
What is Trigeminal neuralgia “tic douloureux”?
Location?
Provoked?
Treatment?
Intense pain
Location: V2/V3 territory
Provocation: chewing, shaving, brushing teeth, touching trigger points
Treatment: carbamazepine (reduces excitability of neurons by working on NA+ channels): also sometimes anti-depressants
What is Tempromandibular jointdisorder (TMD)
Symptoms?
Cause? (5)
Treatment? (3)
Symptoms: chronic pain in joint of jaw, muscles of mastication, recurrent headaches, ear pain
Cause: Teeth grinding and clenching at night (also gum chewing, fingernail biting, trauma to jaw)
Treatment: mouth guard, NSAIDS, Stress management
