Lesson 5: Sensory Pathways Flashcards
What are fasciculus?
Bundles of fibres
Where do all pathways give off information to?
The reticular formation
What receptors convey information about pain and temperature?
Free nerve endings
What receptors convey information about touch and temperature?
Expanded tip endings - Merkel receptors and Ruffini endings
What receptors convey information about discriminative touch, vibration and proprioception?
Encapsulated endings - Pacinian corpuscles and Meissner corpuscles
What modalities does the spinothalamic pathway communicate?
Pain and temperature
What is the pathway of information in the spinothalamic pathway, from reception to the cerebral cortex?
Free nerve endings receive the information, which travels to dorsal root ganglions, where it synapses on primary neuron cell bodies, which then travel to the dorsal horn, where they synapse on secondary order neuron cell bodies. The information decussates immediately, and ascends via the lateral fasciculus to the VPL of the thalamus. It there synapses onto the cell body of the tertiary neuron, which travels via the internal capsule to the parietal lobe.
What is the medial lemniscus pathway?
Encapsulated endings receive information, which travels to synapse on the primary neuron cell body in the dorsal root ganglion, and then into the spinal cord. It ascends via the fasciculus to the closed medulla, where it synapses on the second order neurons, and crosses in the medial lemniscus. It travels up to the VPL, where it there synapses on the third order cell bodies, which travel via the internal capsule and the corona radiate to the parietal lobe
What modalities does the dorsal columns pathway pick up?
Discriminative touch, vibration, proprioception
What information ascends via the fasciculus gracilis, and what ascends via the fasciculus cuneatus?
Cuneatus: arms
Gracilis: legs
What information does the trigeminothalamic tract contain?
Facial information from the trigeminal nerve
What is the pathway of pain and temperature information in the trigeminothalamic tract?
It synapses on the trigeminal ganglion, and then travels downward briefly to synapse on the spinal tract of the trigeminal nerve. The second-order neuron then crosses and ascends in the sensory lemniscus up to the VPM.
What is the pathway of touch and pressure, and of proprioception in the trigeminothalamic tract?
After synapsing on the trigeminal ganglion, this primary neuron synapses on the chief sensory nucleus, and then most of it crosses and ascends in the sensory lemniscus up to the VPM.
What modalities does the spinocerebellar tract contain?
Unconscious proprioception
What is the pathway of information in the spinocerebellar tract? What is different about it?
The information enters at the dorsal horn, and synapses here onto the secondary neuron. It then travels ipsilaterally via the fasciculus. At the medulla, it leaves the brainstem via the inferior cerebellar peduncle. It then travels to the cerebellum. It does not have a tertiary neuron.
