The Lumbar Sympathetic Trunk and Its Branching Variability: Relevance for Clinical and Interventional Strategies

Area of Science:

• Anatomy
• Embryology
• Autonomic Nervous System

Background:

• Precision medicine requires detailed knowledge of lumbar sympathetic anatomy for treating pain and vascular disorders.
• Existing anatomical descriptions of fetal lumbar sympathetic pathways are incomplete.

Purpose of the Study:

• To provide a comprehensive description and classification of fetal lumbar sympathetic communicating branches.
• To detail the distribution of these branches to lumbar spinal nerves.
• To map the origin of lumbar splanchnic nerves.

Main Methods:

• Detailed sub-macroscopic dissections of lumbar and retroperitoneal regions in 25 human fetuses (50 sides).
• Systematic classification and counting of communicating branches (superficial, deep transverse, deep discal).
• Analysis of lumbar splanchnic nerve origins and sympathetic trunk ganglia.

Main Results:

• The lumbar sympathetic trunk typically has three ganglia (L2 and L3 consistently present).
• 466 communicating branches were identified, with deep transverse branches being most consistent.
• All lumbar spinal nerves received branches, but distribution varied; most splanchnic nerves originated from L1 and L2.

Conclusions:

• Fetal lumbar sympathetic trunk anatomy exhibits significant variability but is more consistent than the cervical region.
• Detailed anatomical knowledge is essential for effective lumbar sympathetic trunk interventions and safer retroperitoneal surgeries.