The ANS Flashcards
What does the lateral horn of the spinal cord contain?
T1 and L2/L3 - sympathetic (thoracolumbar).
S2-S4 - parasympathetic (sacral).
Where does the spinal cord end?
How is the vertebral column innervated below this?
L1/L2.
Differential growth.
How is sympathetic supply distributed throughout the whole body?
Sympathetic fibres between T1 and L2/L3 are spread through bilateral sympathetic chains, which run paravertebrally from C1 to Cc1.
What is the function of white rami?
Myelinated and preganglionic.
From spinal nerve to spinal cord.
(Synapses in spinal cord send signals to grey rami).
What is the function of grey rami?
Unmyelinated and postganglionic.
From spinal cord to spinal nerve.
How do spinal nerves communicate with the sympathetic chain?
Through the rami.
(T1 to L2/L3).
What do spinal nerves contain?
Sensory / motor / sympathetic fibres.
How do preganglionic fibres ensure all parts of the body have sympathetic supply?
They travel up or down the sympathetic chain without synapsing, to synapse at a sympathetic ganglion and enter the spinal nerve at that level.
(T1 to L2/L3).
Where do sympathetic fibres synapse?
- In the chain at the same level.
- Up or down the chain, different level.
- Pass through the spinal cord without synapsing, and synapse in an autonomic ganglion in the abdomen lying outside the spinal cord (splanchnic nerves - only abdominal organs).
How do the face and head receive synapses?
Sympathetic fibres (T1 to L2/L3) synapse in cervical ganglia and climb up the blood vessels.
What happens if sympathetic fibres to the face and head are stretched or damaged?
Horner’s syndrome.
Partial ptosis - drooping upper eyelid.
Miosis - pupil constriction.
Anhydrosis - decreased sweating.
How are nociceptive and sensory impulses used in the ANS?
Goes to the spinal cord via the dorsal root.
Mainly in sympathetic afferent fibres.
(Parasympathetic afferent fibres in the pelvis).
Causes dull pain, cramps, and irritation.
Where do parasympathetic nerve fibres come from?
The CNS (craniosacral).
What are pelvic splanchnic nerves?
S2-S4 spinal nerves carrying parasympathetic fibres to pelvic organs.
What do pelvic splanchnic nerves do?
Emerges from vertebral column (S2-S4).
Preganglionic axons synapse with parasympathetic ganglions close to or within the pelvic target organ.
Postganglionic fibres supply the organ.
