gray rami communicantes

gray ra·mi com·mu·ni·can·tes

short nerves arising from the lateral aspect of the sympathetic trunk conducting nonmyelinated postsynaptic sympathetic nerve fibers from the sympathetic trunk to the initial portions of all 31 pairs of ventral primary rami of spinal nerves for distribution by all parts (including the dorsal primary ramus) of the spinal nerve. The gray rami are the parietal branches of the sympathetic trunks because all postsynaptic fibers to be distributed to the body wall (including limbs) must pass through them.