Functional anatomy of ANS part I Flashcards
Two types of motor systems: Somatic (voluntary) and autonomic (non-voluntary)
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autonomic divided into…
parasympathetic/sympathetic systems
nerve definition?
A bundle of axons (depending on the location, may be called a rootlet, root, trunk, division, cord, ramus, nerve or branch)
nerve fiber definition?
Another term used to describe an axon
ganglion definition?
An aggregation of functionally related nerve cell bodies OUTSIDE the central nervous system – can be sensory or motor
nucleus definition?
An aggregation of functionally related nerve cell bodies INSIDE the central nervous system
motor (efferent) neurons definition?
Nerve cells whose axons carry impulses (action potentials) out to muscles or glands (effector organs)
sensory (afferent) neurons definition?
Nerve cells whose processes carry impulses (action potentials) to the central nervous system
What does the somatic nervous system allow us to do?
Allows us to act on the external environment
The neurologic substrate that allows the individual to respond voluntarily to consciously perceived sensory signals
What does the autonomic (self-governing) nervous system (ANS) allow us to do?
Allows us to act on the body’s internal environment
The neurologic substrate that acts to maintain homeostasis
We are not aware of the workings of the ANS
ANS sensory signals are not perceived consciously
Most ANS motor activities are not under voluntary control
Both the somatic NS and the ANS have sensory neurons that carry singles into what???
integrative neurons!!
these are located within the brain and spinal cord and they construct an appropriate response
motor neurons carry response back to effector cells
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Our entire behavioral repertoire can be reduced to combinations of these two actions:
- The somatic NS causes voluntary muscles to contract
- The ANS causes or modifies involuntary muscle contraction and glandular secretion
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- The ANS has preganglionic neurons… these cell bodes reside where?
- The preganglionic fibers (axons) then travel and synapse at post ganglionic neurons… where do these cell bodies reside?
- the postganglionic fibers (axons) then travel to target organs
- Cell bodies residen in the CNS! This is a nucleus
2. cell bodies reside outside the CNS in the periphery. This is a ganglion
target organs for ANS are visceral effectors… this includes?
Visceral effectors (cardiac muscle, smooth muscle, glands) in head, thoracic cavity, abdominopelvic cavity, body wall and limbs
what neurotransmitter is released at the ganglions/at the effector for parasympathetic?
acethylcholine for both locations!
what neurotransmitter is released at the ganglions/at the effector for sympathetic?
ganglion - acetylcholine
effector - norepinephrine
somatic nervous system only has one axon (no preganglionic axon, etc)… what neurotransmitter released?
acetycholine
What are the four functional modalities that are found in a typical spinal nerve?
General Somatic Afferent (GSA)
General Somatic Efferent (GSE)
General Visceral Afferent (GVA)
General Visceral Efferent (GVE)
General Visceral Efferent controls…
sweat glands, erector pilorum muscle, vasculature smooth muscle, gut tube
The spinal cord is located in the upper 2/3 of the vertebral canal… how many spinal nerves?
31 pairs of spinal nerves
The Conus medullar is = end of the spinal cord.. where is it located?
L2 adults
L3 neonate
what enlargements are on the spinal cord?
cervical (c5-T1) - brachial plexus
lumbosacral (L1 to S3)
what makes the butterfly shape on the spinal cord?
gray matter!
make sure to look at all of the diagrams on these slides!!
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the dorsal root is sensory or motor?
SENSORY!!
what is in the ventral horn?
cell bodies of motor neurons
the spinal nerve is a mixed nerve… it has both sensory and motor components!
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sympathetic chain/trunk runs on either side of the vertebral column… also called the paravertebral ganglia
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the sympathetic chain runs from what level to what level?
base of the skull to the sacrum
what connects the sympathetic chain to spinal nerves?
gray and white rami communicantes
white vs gray rami… where are they placed?
white is more lateral, gray is more medial
spinal ganglion off of the dorsal root….
the gray and white rami are off of the spinal nerve (white off of the ventral rami)
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dorsal = sensory ventral = motor
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the thoracolumbar segment of the ANS is what?
the craniosacral regions?
sympathetic
parasympathetic
ventral horn is bigger than the dorsal horn
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where are the lateral horns located?
what is it also called?
what is in the lateral horns?
only at the levels of T1 to L2
intermediolateral cell column (ML)
preganglionic cell bodies - bilateral
ventral horn is what… G??
GSE!!
know slide with somatotopic arrangement of the intermediolateral cell column?
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GSE and GSA fibers enter and leave through the dorsal and ventral roots… no messing around for them
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GVA fibers behave … but problems with GVE! can exit in a ton of funky ways
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Once the preganglionic sympathetic axon is in the sympathetic chain it may take four different anatomical routes to distribute the GVE sympathetic fibers to the body wall and limbs and the visceral structures!
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Preganglionic neurons of the sympathetic division originate where?
in the gray matter of the lateral horn of the spinal cord levels T1-L2 (thoracolumbar outflow)
GVE fiber path…
goes from lateral horn
ventral root
white rami
sympathetic chain ganglion
from there can take many different paths!!
usually goes through gray rami, then out though ventral rami
