Autonomics Of The Body Wall Flashcards
Describe sympathetic routes
From the chain, there are several routes:
- To the body wall and limbs
- To viscera (thoracic/abdominal/pelvic/ perineum organs)
- To organs & structures in the head
ALL preganglionic sympathetics leave the spinal cord…
Between T1 and L2 enter the chain via white rami communicants
What is the sympathetic route?
Lateral horn T1-L2—> ventral root—> spinal nerve/ ventral rami—> WRC—> sympathetic chain
What can sympathetic fibers do after they enter the sympathetic chain?
- Synapse: immediately with a post-ganglionic neuron at the same paravertebral level
- Ascend: in the SC to synapse with a post-ganglionic neuron at a higher paravertebral level
- Descend: in the SC to synapse with a post-ganglionic neuron at a lower paravertebral level
- Pass through the SC without synapsing to continue as a splachnic nerve and synapse at the pre-aortic ganglia
Give examples of sympathetics to body wall and limbs
- sweat glands
- vascular smooth muscles (vessels of the skin, connective tissue and skeletal muscle)
- Arrector pili muscles
Summarize the sympathetic routes to the body wall and limbs to spinal nerves at T1-L2
- Preganglionic axons from cell bodies in lateral horn of spinal segments T1-L2 leave the cord via ventral roots
- Enter the sympathetic chain via WRCs
- Synapse in ganglia at the same spinal level
- Postganglionics exit the chain via GRC to join spinal nerves T1-L2
- Dorsal and ventral rami of these spinal nerves innervate the body wall at T1-L2 levels
- Dorsal and ventral rami of these spinal nerves innervate the body wall at T1-L2 levels
Outline the pathway of. Sympathetics to spinal nerves above T1-L2
- Preganglionic axons from the cell bodies in the lateral horn of upper thoracic segments leave the cord via ventral roots
- Enter the chain via WRCs
- Ascend in chain
- Synapse in cervical ganglia
- Postganglionics exit chain via GRCs to follow spinal nerves C1-C8
- Dorsal and ventral rami of these spinal nerves innervate neck/upper limbs above T1 level
Outline the sympathetics of the body wall transmission below T1-L2
- Preganglionic axons from cell bodies in lateral horn of lower thoracic and upper lumbar spinal segments leave the cord via ventral roots
- Enter the synaptic chain via WRCs
- Descend the chain
- Synapse in lower lumbar and sacral chain ganglia
- Postganglionics exit the chain via GRC to join spinal nerves L3-S5
- Dorsal and ventral rami of these spinal nerves innervate the body wall below L2 and lower limbs
Give an overview on parasympathetic outflow
Cranial outflow
-Cranial nerves- 3, 7, 9,10 serve the head and neck
Sacral outflow- S2-S4
-GUT and pelvic organs
What are the sacral parasympathetics of the parasympathetic system?
Preganglionic parasympathetic:
-cell bodies in a small “lateral-horn-like area” of sacral spinal cord(S2-S4)
- axons travel on the ventral roots to spinal nerves and then ventral ramp of S2-S4
- Leave the ventral rami as pelvic splachnic nerves to enter the pelvic plexus
Postganglionic- nerves are located at or in the walls of target organs in the pelvis (such as the urinary bladder)
CNS portion of the autonomic nervous system requires…
Input from the body
Receives this via visceral afferents
- stretch
- temperature
- chemical changes
- pressure changes
Describe visceral sensory fibers
- Visceral sensory fibers traveling with sympathetics and parasympathetics are called visceral afferents
- These VA fibers travel along with the fibers from the PSNS AND SNS to back the CNS
- The cell bodies of visceral afferents are found in the DRG of the spinal segment where the sympathetic or parasympathetic stimulus leaves
Contrast visceral afferents or parasympathetic & sympathetic nervous system
Visceral afferents traveling with parasympathetics:
-Mediate unconscious sensations such as atrial stretch or GI stretch
-Results in involuntary physiological responses, eg. Enhanced peristalsis, decreased heart rate, blood pressure , etc.
Visceral afferents traveling with sympathetics
-Mediate conscious sensations that are usually painful
-Responds to ischemia, distension (abnormal stretch), inflammation, or spasmodic contraction of smooth muscles
What is refferr3d pain?
Occasionally, sensory information that enters the spinal chord from one location can be interrupted by the CNS as coming from another location that is innervated by the same spinal chord level
How does refferred pain occur?
Can occur when information coming from the viscera (an area of low sensory output) enters the spinal cord at the same level as information coming from the body wall (an area of high sensory output)
This can result in the pain being interpreted as coming from the area of high sensory out put
