Final answer:
The sympathetic nerves, specifically linked with the celiac plexus and splanchnic nerves, are the ones related to the posterior side of the kidney and should be carefully preserved during a biopsy.
Step-by-step explanation:
When performing a kidney biopsy from the posterior side, one must be cautious not to injure the sympathetic nerves. These nerves are responsible for innervating the kidneys and they play a critical role in adjusting blood flow and filtration rates within the organs. The sympathetic nerves associated with the kidneys are part of the autonomic nervous system and are linked with the celiac plexus and splanchnic nerves. Injury to these nerves during a biopsy could result in altered renal function or other complications due to their importance in regulating renal blood flow and filtration.