The pattern of the thoracic splanchnic nerves as they pass through the diaphragm

The formation and structure of the greater, lesser, and least thoracic splanchnic nerves is highly variable in their intrathoracic as well as their subdiaphragmatic portion. Splanchnicectomies for pain control of otherwise intractable upper abdominal pain and other surgical procedures are dependent on the detailed knowledge of the anatomy of these nerves and their variations. Many commonly used anatomical illustrations depict the passage of the thoracic splanchnic nerves through the diaphragm uniformly as three nerves penetrating the crura in three separate locations along a rough superoinferior line. As this pattern does not correspond with our own sporadic observations, we performed a series of dissections to study the exact anatomy of this area. Dissections of 24 donors revealed that the most common pattern of diaphragmatic passage of these three nerves is through a single location in each crus. From this crural passageway, the three nerves then diverge to reach their targets, with the greater thoracic splanchnic nerve bending anteriorly at nearly 90 degrees to enter the posterolateral edge of the celiac ganglion. Modern anatomical illustrations should depict these most common patterns of the subdiaphragmatic portion of the thoracic splanchnic nerves and mention the great variability of their formation and structure.