ganglions : overview

Ganglia are collections of nerve cell bodies located outside the central nervous system (CNS), which includes the brain and spinal cord. They are an essential part of the peripheral nervous system (PNS) and play a role in relaying signals and coordinating various functions within the body. There are two main types of ganglia: sensory ganglia and autonomic ganglia.

**1. Sensory Ganglia:**

Sensory ganglia are responsible for transmitting sensory information from the body to the CNS. The most well-known sensory ganglia are the dorsal root ganglia, which are located along the dorsal roots of the spinal nerves. These ganglia contain the cell bodies of sensory neurons that transmit information about touch, pain, temperature, and other sensory stimuli from the body to the spinal cord and brain.

**2. Autonomic Ganglia:**

Autonomic ganglia are associated with the autonomic nervous system, which controls involuntary functions of the body such as heart rate, digestion, and respiration. There are two types of autonomic ganglia:

- **Paravertebral Ganglia:** These are located near the spinal cord, along the sympathetic chain of the autonomic nervous system. They play a role in the fight-or-flight response and other sympathetic functions.

- **Prevertebral Ganglia:** These are located near specific organs and are involved in the regulation of parasympathetic functions, which include rest-and-digest activities.

To give you a few examples of specific locations:

- The sympathetic chain ganglia are located on either side of the vertebral column, close to the spinal cord

.

- The celiac ganglia are prevertebral ganglia located near the stomach, liver, and other abdominal organs.

- The dorsal root ganglia are located adjacent to the spinal cord, where dorsal nerve roots enter the spinal column.

Overall, ganglia are distributed throughout the body and serve as essential relay points for sensory and autonomic signals to and from the central nervous system.

"Thoracolumbar" and "craniosacral" are terms used to describe the two main divisions of the autonomic nervous system (ANS), which controls involuntary bodily functions. These divisions are also known as the sympathetic and parasympathetic nervous systems, respectively. Let's take a closer look at each division:

**1. Thoracolumbar (Sympathetic Division):**

The sympathetic division of the autonomic nervous system is often referred to as the "fight or flight" system. It prepares the body for intense physical activity and responds to stressful situations. The division is characterized by its origin from the thoracic and lumbar regions of the spinal cord.

**Key Characteristics:**

- Origin: The cell bodies of preganglionic neurons of the sympathetic division are located in the thoracic and lumbar segments of the spinal cord.

- Ganglia: The sympathetic ganglia are located in two chains on either side of the spinal cord, known as the sympathetic chain ganglia or paravertebral ganglia.

- Function: The sympathetic division mobilizes energy reserves, increases heart rate, dilates pupils, and redirects blood flow to the muscles, preparing the body for "fight or flight" responses.

**2. Craniosacral (Parasympathetic Division):**

The parasympathetic division of the autonomic nervous system is often referred to as the "rest and digest" system. It is responsible for maintaining normal bodily functions during restful periods and promotes relaxation.

**Key Characteristics:**

- Origin: The cell bodies of preganglionic neurons of the parasympathetic division are located in the brainstem (cranial nerves) and the sacral region of the spinal cord.

- Ganglia: The parasympathetic ganglia are located near or within the target organs they innervate, often referred to as terminal or intramural ganglia.

- Function: The parasympathetic division conserves energy, slows heart rate, stimulates digestion, and promotes activities associated with relaxation and recovery.

In summary, the autonomic nervous system is divided into the sympathetic (thoracolumbar) and parasympathetic (craniosacral) divisions. These divisions have distinct origins, ganglia locations, and functions. The sympathetic division prepares the body for intense activity and stress, while the parasympathetic division promotes relaxation and normal bodily functions during restful periods.

install app