L2: Cutaneous sensation: Touch and pain Flashcards
What is the fiber type of:
* Merkel cells
* Meissener corpuscles
* Ruffini corpuscles
* Pacinian corpuscles
* Free nerve endings
1-4 Alpha Beta
Free nerve endings: C
What fiber types do these receptors have:
* Warm receptors
* Cold receptors
Warm: C
Cold: Alpha delta
What type of touch are these mechanoreceptors responsible for?
1. Meisseners
2. Merkels
3. Ruffini
4. Pacinian
- Light touch
- Texture and edges
- Stretch
- Deep pressure and vibration
What is a receptive feild?
Area of skin that causes a neuron to change activity (area of coverage)
What does two point discrimination test?
Size of receptive feilds. Small receptive feilds are more sensitve
What is the mechanism of cutaneous sensory transduction?
Mechanical stimuli physically opens ion channels and a potential equivalent to the amount of sensation is fired
What speed of adaptation do each of these receptors have:
1. Meisseners
2. Merkels
3. Pacinian
4. Ruffinis
- Rapid
- Slow
- Rapid
- Slow
What is the role of each receptor in perception of texture and pattern:
Slow adapting
Rapidly adapting
Place and duration
Changes in form
Where does somatosensory stimulation enter the spinal cord?
The dorsal root ganglia to the dorsal root.
Once in the spinal cord, where do sensory fibers travel?
1. For touch
2. For pain and temperature
1.Up the posterior/dorsal column
2. Lateral column
Where does the lower body mechanosensation travel up the spinal cord?
Medial posterior column
Where does the upper body mechanosensation travel up the spinal cord?
Lateral posterior column
Where in the caudal medulla do each synapse?
1. Lower body
2. Upper body
- Gracile nucleus
- Cuneate nucleus
What is somatotopic organization based off of?
Density of information recognized by the part of a body, not the body part size.
Where in the thalmus do the neurons for the face/body sensations synapse?
VPMN/VPLN
What receptor is resposible for the reception of capscasin?
VR-1 (vanilloid)
Spicy -> heat
Where are pain receptors located in the body?
THERE ARE NONE
What type of nerve endings are associated with nociceptors?
Free nerve endings
What type of pain receptor is alpha delta?
Excitatory amino acids (gluatamate, aspartate and ATP) responsible for acute pain
What type of pain receptor is a C receptor?
Long lasting pain receptors (dull pain)
What is the full path of lower limb touch from the receptor to the primary somatosensory cortex?
- Mechanosensory fibers enters the dorsal root gangion in the lumbar region and go to the dorsal root
- The stimulus traves ipsilaterally up the gracile tract until it synapses at the gracile nucleus in the medial region of the caudal medulla
- The neurons then cross the spinal cord in the internal arcuate fibers at the caudal medulla
- The fibers travel up the medial lemiscus tract until they synapse in the VPLN
- The impulses then make it to the primary somatosensory cortex.
Lotion-> body
What is the full path of upper limb touch from the receptor to the primary somatosensory cortex?
- Mechanosensory receptor fibers enter the spinal cord in the dorsal root ganglion in the cervical region and enter the dorsal root.
- The signal then travels up the cuneate tract and synapses with the cuneate nucleus in the lateral region of the caudal medulla
- The fibers then cross as the internal arcruate fibers in the caudal medulla
- The signal travels up the medial lemiscus tract and synpases in the VPLN
- The information then travels to the primary somatosensory cortex.
Lotion-> body
What is the path of touch on the face from the receptor to the primary somatosensory cortex?
- Touch fibers enter the spinal cord at the trigeminal ganglion and synapse at the principle nucleus of the trigeminal complex
- The fibers immediately cross the spinal cord at the medial lemiscus and travel up the trigeminal lemiscus tract
- The neuron synapses at the **VPMN **
- The signal travels from there into the primary somatosensory cortex.
Makeup -> face
Where in the spinal cord does pain stimulus cross?
Anterior white comissure
