Segment of Autonomic Nervous System
The ANS is divided into small segments after its origin from CNS. Three segments are Cranial segment, Thoraco lumbar segment and Sacral segment.
Cranial segment
From brain stem with nerve fibers of oculomotor, facial, Glossopharyngeal & Vagus
Thoraco lumbar segment
From spinal cord with ventral root of spinal nerves from T1 or L5or6 segments.
Sacral segment
From spinal cord and the ventral root of S1-S3 Sacral nerves. Preganglonic axons of the parasympathetic division originate in the cell bodies of the brain stem (cranial out flow) and in the terminal segment of (sacral out flow ) of the spinal cord .