sacral ganglion

A sacral ganglion is a ganglion forming part of the sacral portion of the sympathetic trunk. It contains postganglionic sympathetic neurons that receive presynaptic input from preganglionic sympathetic axons descending through the sympathetic trunk from thoracolumbar spinal levels.

Sacral ganglia are located along the anterior surface of the sacrum, forming the terminal portion of the paired sympathetic chains that run on either side of the vertebral column. They are connected to one another and to the lumbar ganglia above, and the two chains converge at the ganglion impar in front of the coccyx.

Sacral ganglia relay sympathetic signals to pelvic organs, blood vessels, and structures of the lower limbs. They are involved in regulating blood flow to pelvic structures, the fight-or-flight responses of pelvic viscera, and some aspects of genitourinary and gastrointestinal function in the pelvis.

Sacral ganglia may be associated with pelvic pain syndromes, complex regional pain syndrome affecting the lower limbs, and nerve entrapment or injury related to sacral fractures or pelvic surgery. Herpes zoster infection can affect the sacral nerve roots and associated ganglionic tissue.

Sacral ganglia may be visualized on MRI of the pelvis and sacrum in the context of nerve or tumor evaluation. Histological examination of excised tissue allows assessment of ganglionic cell populations and inflammatory or neoplastic changes. Nerve conduction studies and electromyography evaluate the functional integrity of associated sacral nerve pathways.