MMED1005 Lecture Notes - Lecture 7: Duodenum, Postcentral Gyrus, Thalamus
7 Jun 2018
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SENSORY PROCESSES
Main points:
- The sensory pathways from the periphery to the CNS
- The variety of sensory modalities
- The concept of receptive field
- The somatosensory cortex, and the concept of somatotopic organisation
- The role of non-neural cells in receptor function (not in this lecture)
- The special senses – hearing, balance, taste, smell (but not vision)
*mainly first four points
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Brief summary of the three stages of sensory processing:
1. Stimulus activates receptor, actin potentials travel to spinal cord
2. Axon branches to influence many cells in the spinal cord. Some send connections to
higher levels
3. Sensory information is processed in the brain, on the side opposite to the stimulus. It
might give rise to a perceived sensation (you might be aware of it)
Spinal cord:
- Sensory fibres enter the spinal cord via the dorsal roots. The dorsal root contains
sensory fibres, whose cell bodies are in the dorsal root ganglion
- The ventral root contains motor fibres
- The roots – dorsal and ventral – combine to form peripheral nerves (spinal nerves)
- (dorsal: the bit toward your back)
- the dorsal root is in the peripheral nervous system, not surrounded by cerebral
spinal fluid,
- there is no ventral root ganglion. Output cell cell bodies are in the central nervous
system
- peripheral nerve trunks do not usually correspond to spinal nerve roots
- shortly after leaving the spinal cord, the roots join and re-arrange to form nerve
trunks
o e.g. the brachial plexus shown above, which includes nerves to the arm and
shoulder
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
The sensory pathways from the periphery to the cns. The somatosensory cortex, and the concept of somatotopic organisation. The role of non-neural cells in receptor function (not in this lecture) The special senses hearing, balance, taste, smell (but not vision) Brief summary of the three stages of sensory processing: stimulus activates receptor, actin potentials travel to spinal cord, axon branches to influence many cells in the spinal cord. Some send connections to higher levels: sensory information is processed in the brain, on the side opposite to the stimulus. It might give rise to a perceived sensation (you might be aware of it) Sensory fibres enter the spinal cord via the dorsal roots. The dorsal root contains sensory fibres, whose cell bodies are in the dorsal root ganglion. Output cell cell bodies are in the central nervous system. *no need to memorise details of the diagram. In the spinal cord, sensory fibres branch and synapse with many other cells.
