So, let's summarize the general plan of the sympathetic nervous system. Presynaptic sympathetic fibers arise within the lateral horn of the spinal cord between T1 and L2 levels of the cord. ALL of these fibers leave the spinal cord in ventral rootlets, travel through the spinal nerve, and then enter the first few millimeters of the ventral primary ramus before leaving to travel to the sympathetic chain within the white rami communicantes.

The sympathetic chains are bilateral strings of paravertebral sympathetic ganglia, connected by interganglionic rami, that lie beside or on the vertebral column.

Once a presynaptic sympathetic neuron reaches the sympathetic chain, it faces a choice. It may:

1. synapse at the level it entered and then either:
   1. leave within a gray ramus communicans to reach the ventral ramus at the level at which it synapsed, or
   2. leave the chain as a direct branch to organs (thoracic visceral nerve, T1-T4/5).
2. travel up or down the chain to synapse at a higher or lower ganglion, where it may either:
   1. leave within a gray ramus communicans to reach a ventral ramus at the level at which it synapsed, or
   2. leave the chain as a direct branch to organs (cervical cardiac nerve or sacral splanchnic nerve) or to a perivascular plexus (internal or external carotid plexus).
3. leave the chain without synapsing, to travel within a thoracic (T5-T12) or lumbar splanchnic nerve to either:
   1. reach a prevertebral (preaortic) ganglion, where it will synapse and then join a perivascular plexus to reach an organ, or
   2. reach cells of the suprarenal medulla to synapse.

These universal truths must be remembered:

1. White rami communicantes only exist to connect T1 to L2 ventral primary rami to the sympathetic chain. The terms "white ramus" and "presynaptic" are not synonymous and interchangeable.
2. Gray rami communicantes exist at ALL spinal nerve levels. EVERY ventral primary ramus is connected to the sympathetic chain by a gray ramus, which carries postsynaptic sympathetic fibers to the VPR.
3. The sympathetic chain exists to carry some of the presynaptic fibers from the T1-L2 levels up to the neck and head and down into the lower abdomen and pelvis.

If you find inner peace with these universal truths, then you have passed the first step on your journey to become an Autonomic Master.