1. Introduction Flashcards
What comprises the CNS? the PNS?
CNS: brain and spinal cord
PNS: autonomic nervous system (ANS) and somatic nervous system (SNS)
What is the function of the autonomic nervous system? What is the composition of the ANS?
the ANS is part of the peripheral nervous system and is responsible for the involuntary control of viscera (organs)
ANS: sympathetic (fight or flight) nervous system & parasympathetic nervous system (rest or digest)
In general, what are the differences between the somatic and autonomic nervous pathways. Describe the autonomic nervous system pathways in general.
SOMATIC: sensory goes to AFFERENT which goes through the anterior ramus to posterior root/rootlet and into the dorsal horn. Then EFFERENT goes through the ventral horn and travel through anterior rami and back to the sensory.
AUTONOMIC: is compose of visceral AFFERENTS (sensory input from organs) and visceral EFFERENTS (motor output to organs)
- sympathetic: organ->trunk->visceral afferent goes to anterior ramus then to posterior root to the dorsal horn.
visceral efferent from lateral horn through anterior root through anterior ramus to trunk to organ
- parasympathetic: visceral afferent from organ to brain and visceral efferent back to organ from brain
Identify the various parts of the spinal cord.
White matter (myelinated axons)
Gray matter(cell bodies, dentrites, unmyelinated axons)
posterior horn
anterior horn
lateral horn
What is the sympathetic trunk/chain?
all sympathetic fibers go through the sympathetic trunk
Where do sympathetic nerves come from? Why?
Sympathetic nerves come from T1-L2 => the lenght of the thoracolumbar spinal cord (not in lumbar or sacral)
What is the function of the lateral horns? where are they found?
they provide the cell bodies for the visceral efferent neurons and can only be found in the thoracic spinal cord
Compare and describe the sympathetic and parasympathetic nervous system pathway.
- SYMPATHETIC
Presynaptic neuron: (CNS - short axon) - synapse @ sympathetic ganglion + releases acetylcholine -> Postsynaptic neuron (in periphery, long axon) synapse at target organ + releases norepinephrine
2.PARASYMPATHETIC
Presynaptic neuron (CNS long axon) synapses at postsynaptic neuron in periphery and releases acetylocholine
Post synaptic (short axon) synapses at target organ and releases acetylcholine
PRESYNAPTIC NEURONS: MYELINATED
POSTSYNAPTIC: UNMYELINATED
What is the function of the sympathetic trunk?
sympathetic nerves orginate from T1-L2 but they need to travel beyonf that thus the trunk is an extension at top and bottom to do upper and lower limbs
Which nerves compose our parasympathetic nervous system?
Cranial nerves: responsible for higher parasympathetic innervation
CN III: ophthalmic n
CN VII: facial n
CN IX: glossopharyngeal n
CNX: vagus n
+ S2-S4 (for lower and pelvic innervation)
What is the paravertebral ganglia?
paravertebral ganglia: right and left sympathetic trunk => trunks run on either side of the the vertebral body from C1 down to the pelvis
Where do the sympathetic trunks most commonly sit? on the anterior ramus or posterior?
most commonly the anterior ramus because anterior ramus does all structures whilst posterior ramus only does back and skin
How do the sympathetic trunks attach to the anterior and posterior rami?
through white and gray communicans: white communicans (myelinated) are presynaptic sympathetic neurons and grey are post synaptic sympathetic neurons
they both meet at the sympathetic ganglia
Describe the 4 types of sympathetic pathways.
Why are there only grey communicans in the upper and lower limb?
bc sympathetic nerves originate from T1-L2. past this, there can only be post synaptic neurons as presynaptic neurons cannot be generated, thus only gray rami communicans
Identify the 3 structures
orange: vagus nerve
blue: sympathetic trunk
green: splanchnic nerves
