A patient with a C8–T1 cord lesion (complete) develops loss of sweating and vasodilatation in the ipsilateral hand. The preganglionic sympathetic fibres responsible for the hand originate from:

• A T1 lateral horn neurons whose axons exit via the first thoracic nerve only
• B C8 lateral horn neurons — the sympathetic outflow includes cervical segments
• C T2–T5 lateral horn neurons whose axons exit the cord and synapse in the inferior cervical and stellate ganglia ✓
• D T8–T10 lateral horn neurons, reaching the hand via the greater splanchnic nerve

Explanation

Sympathetic preganglionic neurons for the upper limb reside in the intermediolateral cell column of the thoracic cord (principally T2–T5), not in cervical or lower thoracic segments — the sympathetic outflow is exclusively thoracolumbar (T1–L2). Their axons exit via the thoracic ventral roots, travel as white rami communicantes to the sympathetic chain, ascend, and synapse in the inferior cervical ganglion and stellate ganglion (fusion of C8–T1 ganglia). Postganglionic fibres then travel with the brachial plexus to the hand. Lesions at C8–T1 disrupt the preganglionic input rather than the preganglionic neurons themselves, producing ipsilateral Horner syndrome and anhidrosis of the hand.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.