Chapter 15 - Section 15.2 - Anatomy of the Autonomic Nervous System - Before You Go On - Page 568: 3

The sympathetic division of the autonomic nervous system is often referred to as the "thoracolumbar division" because its preganglionic neurons originate from the thoracic and lumbar regions of the spinal cord. This naming convention is based on the specific anatomical locations of the preganglionic neurons' cell bodies within the spinal cord. 1. Origin of preganglionic neurons: - In the sympathetic division, preganglionic neurons originate in the intermediolateral cell column of the spinal cord. - The intermediolateral cell column is primarily found in the thoracic and lumbar regions of the spinal cord, extending from the T1 (first thoracic) to L2 (second lumbar) segments. - These neurons are responsible for transmitting signals from the central nervous system to the sympathetic ganglia. 2. Path of preganglionic axons: - After their origin in the thoracic and lumbar regions, the preganglionic axons travel out of the spinal cord through the ventral roots. - They then enter the sympathetic chain (also called the paravertebral chain or sympathetic trunk), which runs alongside the vertebral column on both sides. - The sympathetic chain contains a series of ganglia, or clusters of nerve cell bodies, that are interconnected by nerve fibers. These ganglia extend from the cervical (neck) region to the sacral (pelvic) region, running along the entire length of the vertebral column. 3. Synaptic connections: - The preganglionic neurons in the thoracic and lumbar regions synapse with postganglionic neurons located in the sympathetic ganglia within the chain. - Postganglionic neurons then distribute signals to target organs and tissues throughout the body. So, while the sympathetic chain does extend from the cervical to the sacral regions, the "thoracolumbar division" terminology emphasizes the origin of the preganglionic neurons in the thoracic and lumbar regions of the spinal cord. This naming convention helps to distinguish it from the "craniosacral division" of the autonomic nervous system, also known as the parasympathetic division, where preganglionic neurons originate from cranial nerves and the sacral region of the spinal cord.

The sympathetic division of the autonomic nervous system is often referred to as the "thoracolumbar division" because its preganglionic neurons originate from the thoracic and lumbar regions of the spinal cord. This naming convention is based on the specific anatomical locations of the preganglionic neurons' cell bodies within the spinal cord. 1. Origin of preganglionic neurons: - In the sympathetic division, preganglionic neurons originate in the intermediolateral cell column of the spinal cord. - The intermediolateral cell column is primarily found in the thoracic and lumbar regions of the spinal cord, extending from the T1 (first thoracic) to L2 (second lumbar) segments. - These neurons are responsible for transmitting signals from the central nervous system to the sympathetic ganglia. 2. Path of preganglionic axons: - After their origin in the thoracic and lumbar regions, the preganglionic axons travel out of the spinal cord through the ventral roots. - They then enter the sympathetic chain (also called the paravertebral chain or sympathetic trunk), which runs alongside the vertebral column on both sides. - The sympathetic chain contains a series of ganglia, or clusters of nerve cell bodies, that are interconnected by nerve fibers. These ganglia extend from the cervical (neck) region to the sacral (pelvic) region, running along the entire length of the vertebral column. 3. Synaptic connections: - The preganglionic neurons in the thoracic and lumbar regions synapse with postganglionic neurons located in the sympathetic ganglia within the chain. - Postganglionic neurons then distribute signals to target organs and tissues throughout the body. So, while the sympathetic chain does extend from the cervical to the sacral regions, the "thoracolumbar division" terminology emphasizes the origin of the preganglionic neurons in the thoracic and lumbar regions of the spinal cord. This naming convention helps to distinguish it from the "craniosacral division" of the autonomic nervous system, also known as the parasympathetic division, where preganglionic neurons originate from cranial nerves and the sacral region of the spinal cord.