Sensory Pathways* Flashcards
What are sensory pathways?
They are routes by which information received by sensory receptors in different parts of the body is conveyed to the corresponding primary sensory areas of the cerebral cortex.
What is exteroceptive information?
It reaches consciousness and we are aware of sensory input. We need the association cortex to interpret it and makes sense of it.
What is interoceptive information?
It may reach consciousness but poorly localised.
Where do exteroceptive pathways convey information from?
Somotosensory receptors on the body surface conveying touch, temp, pain and pressure.
Special sensory receptors conveying taste, smell, vision or hearing conveying organs of special sense.
What are the three neurons that somatosensory pathways use?
The first order neuron = conveys info from receptor to CNS.
The second order neuron = conveys info from lower CNS to the thalamus.
The third order neuron = conveys info from the thalamus to the sensory cortex on the opposite side from which sensation arises.
What are the two somatosensory pathways called?
Anterolateral pathway - carrying touch, pain and temperature.
Dorsal column pathway - carrying discriminative touch and proprioceptive information.
What happens if the primary sensory neurons are damaged?
it will cause an absence of sensation from the region of the body supplied by those nerves.
What happens if the thalamic projection neurons are damaged?
Loss of sensation from the body below level of lesion.
What if the spinal cord is damaged on one side only?
Touch, pain and temperature info from the opposite side is lost, proprioceptive info from same side is also lost.
What do the auditory pathways do?
They convey sound from the cochlea to the auditory complex. Unlike somatosensory pathways they cross and recross repeatedly.
What do the vestibulocochlear nerves convey?
They convey auditory info to the cochlear nuclei in the medulla.
Where is information from each cochlear nucleus distributed to?
The superior olivary nuclei in the pons on both side.
How does auditory information pass? And how do the muscles protect the inner ear?
It passes from the superior olivary nuclei to the inferior colliculi. They send collateral axons to the nuclei controlling the stapedius and tensor typani muscles.
They dampen vibrations and lessens the potential damage to inner ear?
What important connections do the inferior colliculi have?
- nuclei controlling eye movement.
- spinal cord controlling muscles of the neck.
- spinal cord controlling postural muscles.
