The preganglionic sympathetic fibres supplying the adrenal medulla differ from all other sympathetic pathways because they:

• A Travel in the greater splanchnic nerve and synapse directly on chromaffin cells without an intermediate postganglionic neuron ✓
• B Synapse in the paravertebral chain ganglia before reaching their target
• C Use vasoactive intestinal peptide as their neurotransmitter
• D Exit the spinal cord at sacral levels S2-S4

Explanation

The adrenal medulla is a modified sympathetic ganglion where chromaffin cells are the equivalent of postganglionic neurons. Preganglionic sympathetic fibres (T5-T9) travel in the greater splanchnic nerve, pass through the coeliac ganglion without synapsing, and terminate directly on chromaffin cells. Thus, no separate postganglionic neuron exists. This is unique — all other sympathetic targets require a two-neuron chain with the synapse in a ganglion. Acetylcholine is the preganglionic transmitter at the chromaffin cell nicotinic receptor. Sacral outflow S2-S4 is parasympathetic, not sympathetic.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.