4- Toothache Flashcards
General sensory pathways carry information from what?
From different modalities:
Skin, mucus membranes, joints and muscles to the brain
Give an example of pain pathways from toothache and the body?
- The Spinothalamic pathway
2. The Dorsal column pathway
What can we call general sensory pathways?
Somatoesthetic pathways
What are the modalities of the spinothalmic pathway?
- Pain
- Temperature
- Simple touch and some light pressure
Describe what carries the nerve impulses in the spinothalmic pathway
Carried via thin, poorly myelinated or unmyelinated fibres
Conduction relatively slow
What are the modalities of the Dorsal column pathway?
- Discriminative touch
- Pressure
- Vibration
Describe what carries the nerve impulses in the Dorsal column pathway
Carried via large diameter, heavily myelinated fibres
Fast conduction
What is grey matter?
A collection of nerve cell bodies
What is white matter?
Axons with myelin sheaths
What 2 parts make up a Neurone?
Cell body
Axon
What is the grey matter described as in the brain?
As the cortex of the brain
Where is the grey matter found in the spinal cord?
In the inside
Where is the white matter found in the spinal cord?
On the outside
What is a collection of grey matter called inside the central nervous system?
A nuclei or nucleus
What is a collection of grey matter called inside the peripheral nervous system?
A gangli or ganglion
What is the white matter described as in the brain?
A pathway or tract
How many pairs of spinal nerves do we have?
31
How many pairs of cranial nerves do we have?
12
What type of nerves are the spinal nerves?
They are mixed fibre nerves (have both motor and sensory fibres)
What type of nerves are the cranial nerves?
They are mixed fibre nerves (have both motor and sensory fibres)
What are dermatomes?
A specific region of skin of the body innervated by a single spinal nerve
What to dermatomes allow us to do?
Create a sensory map of the body so that if a patient is not feeling sensation is a specific area we know exactly which spinal nerve has been affected
Where is the primary somatosensory cortex located?
In the post central gyrus
What information is received by the primary somatosensory cortex ?
- Pain and temperature sensation
2. Touch sensation
How many neurones make up a sensory pathway
3
Where is the primary motor cortex located?
In the pre central gyrus
Describe the 1st order neurone that makes up the sensory pathway
Travels From the PNS to CNS.
Cell bodies in peripheral ganglia. It is Pseudounipolar.
What is a Pseudounipolar neurone?
This neurone has one projection from the cell body that has split into two branches
One branch runs to the periphery and the other to the spinal cord
What is a unipolar neurone?
A neurone that has only one projection from the cell body
Describe the 2nd order neurone that makes up the sensory pathway
Axons cross midline.
It Runs to thalamus (part of diencephalon).
Describe the 3rd order neurone that makes up the sensory pathway
It Run from the thalamus to the cerebral cortex (primary somatosensory area)
What are connections between neurones called?
Synapses
Where is the Spinothalamic pathway located in the spinal cord?
In the ventral white column and a little in the lateral white column
Where do fibres from our receptors in skin enter from in the Spinothalamic pathway?
At the dorsal root ganglion where it enters the dorsal horn
What happen to the 1st order neurone once it reaches the dorsal horn in the Spinothalamic pathway?
It will either: 1. synapse with a 2nd order neurone in the dorsal grey horn
2. May ascend 1-2 in the spinal cord then synapse
Where does the 2nd order neurone travel to in the Spinothalamic pathway?
The 2nd order neurone crosses the midline into the ventral white commissure
It then reaches the Spinothalamic tract then ascends to the thalamus
How does the body distinguish which part of the body pain signals are coming from?
As the fibres are organised in a Somatotopic fashion so that fibres from each part of the body travel in a slightly different position
Give a general overview of the Spinothalamic pathway
- 1st order neurone enters the dorsal root ganglion
- Synapses with our 2nd order neurone
- 2nd order neurone crosses the midline
- Enters the ventral white commissure
- Travels up the Spinothalamic tract
- Crosses the medulla (tract name changes to Spinal lemniscus)
- Synapse with 3rd order neurone at the thalamus
- information reaches Post-central gyrus
(1˚ Somatosensory cortex )
When does the Spinothalamic tract become the Spinal lemniscus?
After the neurone has crossed the medulla
Fibres coming from the right side are received at which side of the brain?
The left side due to the crossing of the 2nd order neurone in the spinal cord
What term describes sensory pathways?
Somatotopic
Name cranial nerve V
The trigeminal nerve
What are the 3 division of the trigeminal nerves
V1 Opthalmic
V2 Maxillary
V3 Mandibular
Where is the trigeminal nerve located?
In the Pons
Where are the first 1st order cel bodies of the trigeminal nerve found?
10 neuron cell bodies are
in trigeminal ganglion (TG)
(with one exception)
Where is V1 called and where is it generally located ?
The opthamic division of the trigeminal nerve
Mainly found in the superior region of the face
Which foramen does V1 pass through?
The superior orbital fissure
What is V1 responsive for?
Sensory innervation of the upper face
Above the eyelid
Which foramen does V2 pass through?
Foramen rotundum
What is V2 responsive for?
Sensory innervation between our lower eyelids and lips
Which foramen does V3 pass through?
Foramen ovale
What is V3 responsive for?
Sensory innervation of the lower face and mandible
Also muscles of mastication
What makes V3 special?
It is the only devision of the trigeminal nerve that carries motor fibres as it supplies the muscles of mastication
What innervates our upper teeth?
The maxillary division of the trigeminal nerve
What innervates our lower teeth and lower gums?
The mandibular division of the trigeminal nerve
What is herpes zoster?
infection of the sensory roots of trigeminal nerve
What does the herpes zoster virus lead to?
Chicken pox
What can the herpes zoster virus do once we have had chicken pox?
the virus resides in the sensory roots of specific spinal nerves.
What can reactivation of theherpes zoster virus lead to?
Leads to shingles
What are shingles
Inflammation of one nerve
What do we find in the trigeminal ganglion?
The first order neurone cell bodies
Where is the cranial nerve nuclei located?
Within the brain stem
What do the sensory nuclei of the trigeminal nerve do?
receive information from fibres entering brainstem in cranial nerves
What do the motor nuclei of the trigeminal nerve do?
give rise to motor fibres that leave the brainstem in cranial nerves
What is a nucleus in the brain stem?
A collection of cell bodies
What do nerves that carry a high number of modalities usually have?
A higher number of nuclei
Compare the sensory and motor nuclei of the trigeminal nerve
The trigeminal nerve has a large sensory nuclei but a small motor nuclei
Why does the trigeminal nerve have a small motor nuclei?
Because only the V3 devision of the trigeminal nerve has motor fibres
What is the sensory nuclei of the trigeminal nerve split into?
3 parts: 1. Mesencephalic nucleus 2. Pontine/chief Sensory nucleus 3. Spinal nucleus
Which part of the sensory nuclei of the trigeminal nerve is in charge of pain and temperature modalities?
The caudal part of SPINAL nucleus
Which part of the sensory nuclei of the trigeminal nerve is in charge of simple touch and pressure modalities?
rostral parts of SPINAL nucleus
Go through the pain and temperature pathway of the trigeminal nerve
- Receptor cells picking up painful stimuli sends a nerve fibres
- First order neurone synapses in the trigeminal ganglion
- First order neurone enters the caudal part of SPINAL nucleus
- Synapses with the second order neurone in the spinal nucleus
5, Crosses the midline - ascends up the Trigeminothalamic tracts
7 Reaches the thalamus
Pain felt in the left side of the body is picked by which side of the brain?
The right side due to the crossing of the secondary Nerone over the midline
Pain from the body travels through which pathway?
Spinothalamic pathway
Pain from the teeth travels through which pathway?
trigeminothalamic Pathway
Give some differences between the Spinothalamic pathway and the trigeminothalamic Pathway
- Spinothalamic pathway travel contralaterally in the cord whereas trigeminothalamic Pathway Descend through medulla to spinal nucleus
- Spinothalamic pathway cross at level of spinal cord entry whereas trigeminothalamic pathway Cross below entry
What effect would a lesion on the right lateral medulla have on pain sensation to the face?
You would have loss of pain, temperature, touch and pressure on the same side of the lesion
What effect would a lesion on the right lateral medulla have on pain sensation to the body?
You would have loss of pain, temperature, touch and pressure on the same side of the opposite
