Sensory 11/3/16 Flashcards
What system deals with the cutaneous sensation?
-Dorsal column system
What three general sensations deal with the anterior lateral system?
- Crude touch
- Temperature
- Pain
What three general sensations deal with the dorsal column-Medial lemniscus?
- Proprioception
- Vibration
- Fine touch
Where do sensory pathways start?
-Sensory receptors
T/F
The primary sensory neuron is a pusedo-unipolar neuron?
-True
In the primary sensory neuron what are the two branches?
- Central
- Peripheral
What is another name for the primary sensory neuron cell bodies?
-Dorsal root ganglia
T/F
The peripheral branch of the primary sensory neuron goes to the spinal cord
False
-It goes to the periphery (skin)
T/F
-Sensory receptors are specialized to detect different types of inputs such as fine touch, vibration, and pressure.
True
What type of nerve endings detect pain, temperature, itch (ALS pathway)?
Free nerve endings
What type of receptors detect mechanical inputs?
-Mechanoreceptors
What type of receptors detect muscle stretch, tension, and joint position?
-Proprioceptors
T/F
Muscles give sensory feedback that helps drive the motor system
True
What does the speed of conduction depend upon?
- Axon diameter
- Degree of myelination
What will the neuron look like if it has a fast speed of conduction.
- It will be large
- It will have lots of myelin
What part of the body has the quickest speed of conduction for sensory nerves?
-Proprioceptors of skeletal muscle
What travels faster through the neuron, the proprioceptors of skeletal muscle or the mechanoreceptors of skin?
-Proprioceptors of skeletal muscle
What pathway are proprioceptors of skeletal muscles and mechanoreceptors of skin a part of?
-DCML pathway
What is the receptive field?
-Area detected by a single receptor neuron
What are the ascending branches in the spinal cord?
-Sensory pathways to higher centers
What are descending pathways in the spinal cord?
-Motor pathways from higher centers
How many neurons are involved in the sensory pathway?
Three
What are the cell bodies for the 1st order neuron in the DCML?
-Dorsal root ganglion
What are the cell bodies for the DCML 2nd order neuron?
-Gracile/cuneate nuclei (Medulla)
What are the cell bodies for the 3rd order neurons?
-VPL nucleus (thalamus)
What are the two major divisions of the dorsal column?
- Medial tract (gracile tract)
- Lateral tract (cuneate tract)
What part of the body does the medial (gracile) tract carry sensory information from?
-T6 and below (lower body)
What part of the body does the lateral (cuneate) tract carry sensory information from?
-T6 and above (upper body)
Where does the first synapse occur in the DCML sensory pathway?
-Caudal Medulla in the Dorsal column nuclei
What are the two nuclei in the dorsal column nuclei?
- Gracile nucleus
- Cuneate nucleus
T/F
The first synapse is contralateral in the DCML
False
It is ipsilateral
Where do axons from the second order neuron in the DCML pathway decussate?
-Internal arcuate
After second order neurons decussate in the DCML pathway what do they ascend through?
-Medial lemniscus
If you obliterate the medial lemniscus what side of the body do you lose sensory from?
-The contralateral side
Where does the second synapse in the sensory systems occur?
-VPL of the thalamus
Where do third order neurons ascend to?
-Primary sensory cortex
What does VPL stand for?
-Ventral posterolateral
Where do you find the primary somatosensory cortex?
-Post central gyrus
What system is related to feelings from our body such as temperature, pain, and itch?
-Anterolateral system
T/F
The anterolateral system is associated with emotion
True
In the anterolateral system what do your sensory neuron ending look like?
-Free nerve endings
What do the axons look like in the anterolateral system?
- Thin
- Maybe or maybe not myelinated
What are thin unmyelinated fibers called?
-C fibers
What are thin myelinated fibers called?
-A delta fibers
What are the two major classes of nociceptive neruons
- A delta nociceptors
- Polymodal C-nociceptors
What nociceptive neuron deals with sharp pain?
A-delta nociceptors
What nociceptive neuron deals with slower burning pain?
-Polymodal C-nociceptors
Where does the 2nd order neuron occur in the ALS pathway?
-Spinal cord
When does decussation occur in the ALS sensory pathway?
-Spinal cord
Is the first synapse in the ALS sensory pathway ipsilateral or contralateral?
-Ipsilateral
Where does the axons of the first order neurons in the ALS sensory pathway travel through if they are going up or down a few spinal cord levels?
-Tract of Lissauer
Where do the second order neurons decussate in the ALS pathway?
-Anterior white commissure
What do the second order neurons from the ALS sensory pathway ascend in?
-Anterolateral system
How do you tell if it is the cervical portion of the spinal cord?
-It will have both the gracile and cuneate tracts
What sensory pathway is contralateral in the spinal cord?
ALS
What sensory pathway is ipsilateral in the spinal cord?
-DCML
Where in the brain are both pathways, ALS and DCML, contralateral?
After the DCML decussates in the medulla
T/F
3rd order neurons in the sensory systems pass through the internal capsule
True
