The white rami communicantes carry which type of nerve fibers?

• A Postganglionic sympathetic unmyelinated fibers from sympathetic chain to spinal nerve
• B Preganglionic sympathetic myelinated fibers from spinal nerve to sympathetic chain ✓
• C Preganglionic parasympathetic fibers from craniosacral outflow
• D Somatic motor fibers to erector spinae muscles

Explanation

White rami communicantes (present only at T1–L2 spinal levels) carry myelinated preganglionic sympathetic (B-fibers) from the lateral horn (intermediolateral column) of the spinal cord to the paravertebral sympathetic chain ganglia. They appear white due to myelination. Gray rami communicantes carry unmyelinated postganglionic sympathetic (C-fibers) from the chain back to all spinal nerves for distribution to skin (sweat glands, arrector pili, vasomotor). Gray rami exist at every segmental level while white rami exist only at thoracolumbar outflow levels.

Reference: BD Chaurasia's Human Anatomy, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.