Learning Objective

Describe the anatomical location of ganglia in the sympathetic and parasympathetic divisions of the autonomic nervous system (ANS) and distinguish them from the somatic nervous system.

Location of ANS Ganglia

• Both the parasympathetic (PANS) and sympathetic (SANS) systems have a two-neuron pathway, meaning there is a ganglion (relay station) between the CNS and the effector organ.
• In contrast, the somatic nervous system has no ganglia; a single neuron runs from the CNS to the skeletal muscle.

Sympathetic Nervous System (SANS) – Ganglia Location

Ganglia lie in two paravertebral sympathetic chains that run along either side of the vertebral column.

Additional ganglia are located in prevertebral (pre-aortic) plexuses, such as:

• Celiac ganglion
• Superior mesenteric ganglion
• Inferior mesenteric ganglion

Key idea:

SANS ganglia are far from the target organs (near the spinal cord). Preganglionic fibers = short; postganglionic fibers = long.

Parasympathetic Nervous System (PANS) – Ganglia Location

Most ganglia are located within or near the walls of the effector organs they innervate:

• Heart
• Bronchi
• GI tract
• Bladder, etc.

Key idea:

PANS ganglia are close to or inside the target organs.
Preganglionic fibers = long; postganglionic fibers = short.

Activity