![]() A simple case is a reflex caused by a synapse between a dorsal sensory neuron axon and a motor neuron in the ventral horn. Specific regions of the CNS coordinate different somatic processes using sensory inputs and motor outputs of peripheral nerves. The general senses of somatosensation for the face travel through the trigeminal system. Other cranial nerves contain both sensory and motor axons, including the trigeminal, facial, glossopharyngeal, and vagus nerves (however, the vagus nerve is not associated with the somatic nervous system). Some cranial nerves contain only sensory axons, such as the olfactory, optic, and vestibulocochlear nerves. Whereas spinal information is contralateral, cranial nerve systems are mostly ipsilateral, meaning that a cranial nerve on the right side of the head is connected to the right side of the brain. For sensations below the neck, the right side of the body is connected to the left side of the brain and the left side of the body to the right side of the brain. Cranial NervesĬranial nerves convey specific sensory information from the head and neck directly to the brain. Typically, spinal nerve systems that connect to the brain are contralateral, in that the right side of the body is connected to the left side of the brain and the left side of the body to the right side of the brain. This will help to underscore the relationships between the different components. For the sake of convenience, we will use the terms ventral and dorsal in reference to structures within the spinal cord that are part of these pathways. A branch may also turn into the posterior (dorsal) column of the white matter to connect with the brain. Other branches will travel a short distance up or down the spine to interact with neurons at other levels of the spinal cord. Some of the branches will synapse with local neurons in the dorsal root ganglion, posterior (dorsal) horn, or even the anterior (ventral) horn, at the level of the spinal cord where they enter. The dorsal root contains only the axons of sensory neurons, whereas the ventral roots contain only the axons of the motor neurons. As the spinal nerve nears the spinal cord, it splits into dorsal and ventral roots. Generally, spinal nerves contain afferent axons from sensory receptors in the periphery, such as from the skin, mixed with efferent axons travelling to the muscles or other effector organs. ![]() Describe several reflex arcs and their functional roles.Explain the initiation of movement from the neurological connections.Compare different descending pathways, both by structure and function.Describe the pathway of descending motor commands from the cortex to the skeletal muscles.List the components of the basic processing stream for the motor system.Explain topographical representations of sensory information in at least two systems.Describe the pathway of somatosensory input from the face and compare it to the ascending pathways in the spinal cord.Differentiate between the two major ascending pathways in the spinal cord.Describe the pathways that sensory systems follow into the central nervous system.If you do think about it, suddenly you have to control it again, until you stop thinking about it once more.By the end of this section, you will be able to: If you do not think about it, it just happens. I always found it pretty easy to remember which was which, but you have to remember that even those things which are automatic, and therefore part of the autonomic nervous system, can be done "manually" as well.īreathing is the best example. I just finished studying the functions of the nervous system in my anatomy class. The body is a really interesting machine.Īnd the beauty of it is, when you no longer want or need to control it, or when you cannot, like when sleeping, it all happens for you. This also leads to things like changes in heart rate and even level of consciousness to some extent. I am into meditation and I control my breathing quite regularly. I would love to go further in my education and study more about the complexity of the body. They told us in class, "You aren't dead until you are warm and dead". People have been pulled out of the water after incredible lengths of time and brought back. Respiration, blood flow, heartbeat, everything. For example, when the body is really cold, such as when you fall through a frozen lake, everything slows down to almost a crawl. I learned a lot about the nervous system when I was in Paramedic training, and one thing that really amazed me was how sensitive and adaptive it is.
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