Which mechanoreceptors are high density?
Merkel and Meissner
What do the mechanosensory neurons do at the caudate medulla?
They synapse with the gracile and cuneate nuclei and the their axons crosses over
What is the main role of golgi tendon organs?
Sense tension/force in muscle
What type of signal, excitatory or inhibitory, do interneurons generally produce?
Which subregion of the primary somatosensory cortex receives the most from the ventrio-posterio-lateral thalamus?
What are muscle spindles found?
Amongst muscle fibres
At what level must damage occur for a limb to exhibit upper motor neuron symptoms?
At any level above the motor neurons for that limb
What is anaesthesia
Which nuclei does mechanosensory information from the upper body travel to?
Why is the vertebral column longer than the spinal cord?
The vertebral column extends faster than the spinal cord
What is a motor neuron pool?
All the neurons that innervate a whole muscle
Which mechanoreceptors are low density?
Ruffini and Pacinian
Where do the gracile and cuneate nuclei send their axons to?
The ventero-posterio-lateral nucleus of the thalamus
Where is information from the primary somatosensory cortex sent to?
The secondary somatosensory cortex mainly but also parietal areas 5 and 7
What is the function of muscle spindles?
Modified muscle fibres that are surrounded by sensory nerves - to detect stretch in muscle
Having more receptor fields allows for what?
The ability to distinguish finer details
Which side of the spinal cord do axons for nociception travel?
Opposite to the side of the receptor
Where is the primary somatic sensory cortex located?
What is dysaesthesia?
Abnormal, unpleasant sensation
What is a motor unit?
A neuron and the muscle fibres it innervates
What is the function of the monosynaptic stretch reflex?
To maintain posture/position in response to changing stimuli.
eg. a load is placed on an outstretched hand which causes a reflex contraction of the bicep to account for the load (and relaxation of the triceps)
What is hypoesthesia?
Reduced sense of touch
At what level does the mechanosensory axons cross over the spinal cord?
What is the function of the golgi tendon organ feedback mechanism?
Send negative feedback (via an interneuron) to reduce the force of a movement if there is too much
T/F Somatosensory axons have the fastest signal transduction?
False, they're fast, but still second to muscle spindle axons of proprioception
What are propriospinal connections?
Interconnections that occur within the spinal cord
Somatosensory neurons give off more than one axon, what are they?
One that travels to the CNS
One that synapses in the spinal cord
What is the name of the structure that is a continuation of the spinal cord?
What senses does the somatosensory system mediate?
Sense of touch
What are the four types of mechanoreceptors of the skin?