Corpus: Gray ramus communicans
from Latin: griseus - gray
Synonym: ramus communicans griseus
1. Definition
The gray ramus communicans is a connecting branch between a spinal nerve and the sympathetic trunk (truncus sympathicus).
2. Anatomy
The gray rami communicantes contain postganglionic nerve fibers from sympathetic neurons, whose cell bodies are located in the sympathetic ganglia. These fibers use the respective spinal nerve as a pathway to reach target organs in the periphery, such as blood vessels.
The gray ramus communicans appears macroscopically gray due to the lack of myelination in postganglionic axons.
see also: white ramus communicans
3. Function
The gray rami communicantes extend from the thoracic ganglia into the adjacent thoracic wall, where they innervate blood vessels, sweat glands, and the arrector pili muscles. Some cervical and thoracic ganglia send gray rami communicantes directly to the heart.
The gray rami communicantes from the lumbar ganglia connect to local spinal nerves to supply the abdominal wall and lower extremities. Similarly, the gray rami communicantes from the pelvic ganglia run to the wall of the pelvis and the lower extremities.
4. Source
- Richard L. Drake, Wayne Vogl, Adam W. M. Mitchell: Gray's Anatomy for Students (2007), p. 82