Somatosensory Flashcards
What are the sensory submidalities?
Mechanoreceptors (touch vibration and pressure)
Thermoreceptors (temperature)
Nociceptors (pain)
What are the specialized nerve endings for mechanoreceptors?
Merkel’s disk, Meissner’s corpuscule, Pacinian Corpuscule, Ruffini ending
What are free nerve endings connected to?
Thermal receptors and nociceptors
What are the two components of proprioception?
Sense muscle length and tension
Which mechanoreceotor is linked with muscle length sense?
Muscle spindles
Which mecanireceptor is linked with muscle tension sense?
Golgi tendon organs
What are the four qualities of a stimulus?
Modality, location, intensity and duration
What are the 5 sensory modalities?
Vision, hearing, touch, taste, smell
What enhances the spatial resolution of the 2nd order neurons’ receptive fields?
The neurons’ surround (lateral) inhibition
What are the 4 spinal segments
Cervical, thoracic, lumbar, sacral
Each spinal segment provides … to a particular region of the skin
Sensory inervation
What is the dermatome?
The area of skin and deeper tissues innervantes by a single dorsal root
What are the two sensory pathways?
Dorsal column-medial lemniscal system
Spinothalamic tract
What is the dorsal column-medial lemniscal pathway responsible for?
Vibration, light touch, pressure, proprioception
What is the spinothalamic tract responsible for?
Pain and temperature
What are where are the 3 neurons responsible for the two pathways?
1) 1st order neuron which is the dorsal root ganglion cell
2) 2nd order neuron is ipsilateral to neuron 1 and is located in spinal cord
3) 3rd order neuron in thalamus
What are the 5 steps of the dorsal column-medial lemniscal pathway?
Dorsal columns (spinal cord) Dorsal column nuclei (medulla) Medial lemniscus (brainstem) Ventral posterior lateral nucleus (VPL, thalamus) Primary sensory cortex, S1
What do pain and temperature activate?
Transient receptor potential ion channels
What do lightly myelinated Aalpha fibers register?
Fast, sharp first pain
What do unmyelinated C fibers register?
Register duller, longer lasting second pain
What are the two steps of the spinothalamic tract?
Aalpha and C afferents synapse in the substantia gelatonisa of dorsal horn
Decussate and travel up the cord in the spinothalamic tract to the thalamus (VPL) and then to S1
What are the 3 elements for which the posterior parietal cortex is responsible?
1) involved in somatic sensation
2) analysis where things are from visual inputs
3) involved in sensation of where things are on your body or your interpersonal space
