Flashcards in Ascending Sensory pathways 1 Deck (57)
What are somaesthetic pathways?
perception of bodily sense - pain, temperature, touch and position
What is a spinothalamic pathway?
responds to pain, temp and some touch
What is a dorsal column pathway?
responds to fine, precise touch, vibration and position.
What is proprioception?
What two things does the somaesthetic pathway involve?
From where are different types of modalities of information carried to the brain in the somaesthetic pathway? (4)
2. Mucus membranes
How is each modality detected in somaesthetic pathway?
specific sensory receptors/ specialised nerve endings
What 2 groups does somaesthetic modalities fall into?
1. Essential for survival - Spinothalamic pathway
2. That increase detail - Dorsal column pathway
What modalities are essential to survival?
pain, temperature, some touch and pressure
What types of fibres are modalities that are essential for survival/spinothalamic pathway carried?
thin, small diameter, poorly myelinated or unmyelinated fibres
What is conduction like in modalities that are essential for survival/ spinothalamic pathway?
What modalities increase detail/ dorsal column pathway?
2 point discrimination and vibration, proprioception
What type of fibres carry modalities that increase detail/ dorsal column pathway?
large diameter, heavily myelinated
What is conduction like in modalities that increase detail/ dorsal column pathway?
Which side of the central gyrus of the brain is information from the right side sensed?
left central gyrus
How many neurones are involved in the general sensory pathway?
3 neurone chain
What is in the thalamus?
VPL - ventral posteral nucleus/ Posterior ventral nucleus
What is the 1st order neurone?
- pseudo unipolar cell body
- in sensory ganglion
- centre is ipsilateral
What is the 2nd order neurone?
- axon crosses midline
- ascends to ventral posterior nucleus in thalamus
What is the 3rd order neurone?
- axon projects to post central gyrus - parietal lobe
Where do the cell bodies of the 1st order neurons reside in?
dorsal root ganglia (PNS)
Where do the cell bodies of 2nd order neurons reside in?
CNS ipsilateral gray matter
Where do axons of the 2nd order neurone cross and what do they ascend to?
crosses the midline
ascend to thalamus
Where do the cell bodies of 3rd neurone reside in and where do the axons project to?
axons project to somatosensory cortex
What pathways are somatotopic?
How can synaptic transmission from 1st, 2nd and 3rd neurone be modified?
- neurones not simple relay
- modified by other inputs - descending pathways or convergence/divergence
What is the medial surface of the brain's hemisphere supplied by and what can damage result in?
Anterior cerebral artery
damage to certain features on somatotopic map on post-central gyrus
What is a converging circuit?
several presynaptic neurons that stimulate a single postsynaptic neuron
What is a diverging circuit?
a single presynaptic neurone stimulating several post-synaptic neurone