TBL 3 - Somatic and Autonomic Nervous Systems, Spinal Nerves, and Ganglia Flashcards
CNS vs PNS
Brain and spinal cord vs. spinal nerves, cranial nerves, and autonomic nerves
Multipolar neuron
motor - multiple dendrites with one single axon that could have collateral branches. Efferent axons - signals go away from CNS
Pseudounipolar neuron
sensory - cell body with double process: a peripheral process that brings signals from receptor organs into cell body and a central process that goes from the cell body to the CNS. Afferent axons - signals come to the CNS
Dorsal root ganglion
PNS - where the sensory neurons reside. Aka spinal ganglion. Here the sensory impulse goes from the long peripheral axon to the short central axon which is also the posterior roots of the spinal nerve
Describe what interneurons are and what synapses with them
Mulltipolar, unmyelinated neurons. Synapse with posterior roots that bring in sensory impulse and they either convey information to the motor neurons in anterior horn or to the brain
Which neurons are affected by amyotrophic lateral sclerosis (ALS) and why is the disease ultimately fatal?
Motor neurons are affected. Eventually the respiratory muscles are affected and the person can no longer breathe
What constitutes the somatic nervous system
Cranial and spinal nerves that innervate all parts of the body except the organs, glands, and smooth muscles
What does the autonomic nervous system consist of
Pairs of multipolar neurons that involuntarily regulates the organs, glands, and smooth muscle. Also called visceral nerves. First neuron is in the CNS and the second is in the autonomic ganglion. Sympathetic and parasympathetic
Where do interneurons reside in the spinal cord?
Posterior horns
Are the roots and DRG in the vertebral canal or outside of it?
Inside
Which spinal nerve roots are compressed by disc herniations between vertebrae L4 and L5 and between vertebrae C4 and C5?
L5 and C5
Describe nomenclature of spinal nerves in the cervical and inferior portions
Cervical - named after vertebrae inferior to the IV foramina of exit
Inferior (T, L, S, Co) - named after the vertebrae forming superior margin of exit
Where do posterior and anterior rami form and where do they go?
Immediately after emerging from the IV foramina, the nerves divide into posterior and anterior rami. Posterior to the posterior body wall, anterior to the anterolateral body wall and extremities
Describe the somatic reflex process
Sensory impulse comes to the DRG and then through the posterior rami and into the posterior horn when it synapses with the interneuron. Interneuron synapses directly to the motor neuron generating a response. A second signal is sent to the brain to feel pain
Where are the presynaptic neurons of the sympathetic nervous system located and describe their course until synapse
Intermediolateral (lateral) horns of the spinal cord between T1 and L2. Exit the spinal cord through the anterior rami where the motor neurons exist and synapse in the sympathetic ganglia
What is the paravertebral ganglia
The linkage of the sympathetic ganglia that forms bilateral sympathetic trunks along the vertebral column. The paravertebral column has 3 segments along the 8 cervical vertebrae and than one for each vertebrae through the sacral spinal segment
What goes through the white communicating rami and what goes through the gray communicating rami and what do they do.
Presynaptic sympathetic fibers go from anterior rami into the white communicating rami to the paravertebral ganglia. The postsynaptic sympathetic fibers go from the paravertebral ganglia into the gray communicating rami back into the anterior rami to their destination. Postsynaptic fibers also go into the posterior rami to their destination.
Do all presynaptic fibers go to their corresponding paravertebral ganglia? If not, where to they go and what happens to the postsynaptic fibers.
They can ascend or descend in the cervical or lumbar/sacral paravertebral ganglia. Gray communicating rami send the postsynaptic fibers back to the anterior and posterior rami
