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CNS - brain, SP, cerebellum, brainstem, diencephalon, cranial nerves I and II
- PNS - spinal neves, cranial neves 3-11
- dorsal root ganglia and autonomic ganglia
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**31 spinal nerves and spinal cord segments (think to back and repeat the number and the amount each)
**33 vertebral bodies
**answer below**
- cervical 8
- thoracic 12
- lumbar 5
- sacral 5
- coccygeal 1
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difference between axons in PNS and CNS
- axons in the neurons of PNS form nerves which then form 4 interconnected plexii
- cervical plexus C1-C5
- brachial plexus C5-T1
- lumbar plexus L1-4
- sacral plexus L4-S4
axons in the CNS forms tracts
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difference between neuronal cell bodies in PNS and CNS
- cell bodies in PNS are in ganglia
- dorsal root ganglia
- cranial nerve ganglia
- autonomic ganglia
cell bodies in CNS are called nuclei and are scattered throughout cortex and brainstem levels
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2 nervous system components, what they control and types of control over the body
- somatic nervous system
- skin (sensation), bones, skeletal muscles
- voluntary motor (axons aka general somatic efferent)
- somatic sensory (axons aka general somatic afferent)
- autonomic nervous system - organs, glands, smooth muscle
- visceral motor (axons aka general visceral efferent) **controls sympathetic, parasymp, and enteric)
- visceral sensory (axons aka general visceral afferent)
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how the somatic (voluntary) motor systems work to target voluntary muscle fibers
the pathway has a 2 neuron chain in the cerebral cortex. The upper motor neurons in the primary motor cortex send a signal along somatic motor axon (GSE) to the ventral horn (frontal vision of the lower cervical segment of brain) of the spinal cord. The ventral horn has the lower motor neurons that will send signals out along the axon in the ventral root (root that branches off the spinal cord, exits the spinal column, an continues to a specific part of the body) and into the peripheral or spinal nerve to the voluntary muscle fiber
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difference in sensory axon (GSA)traveling and voluntary motor (GSE) axon traveling
sensory axon will travel in the spinal nerve to enter the dorsal root and will then become a tract within the spinal cord to reach cereb cortex
voluntary motor axons descend from the cereb cortex synapse in the spinal cord and then travel out the ventral root to enter the spinal nerve and peripheral nerve to then activate nerves to a voluntary muscle
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venous drainage of the spinal cord explained
there are 3 anterior and posterior spinal veins in the spinal cord. They communicate with each other and drain into the anterior and posterior medullary veins. those veins join the interal vertebral (epidural) plexus which together communicate with dural sinuses and then vertebral veins. The internal vertebral plexus also communicates with the external vertebral plexus on the outside of the vertebrae
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ganglia define
a mass of nerve tissues existing outside the central nervous system
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