Which anatomical landmarks are crucial for performing a proximal paravertebral block?

• A. L1, L2, L3
• B. T13, L1, L2
• C. Rib 12, L3, L4
• D. Sacrum, L1, T11

Answer: (A)

The proximal paravertebral block technique involves targeting specific spinal nerves that supply the structures of the abdomen, particularly in large animals like cattle. The correct anatomical landmarks for this block are focused on the vertebrae L1, L2, and L3.

By selecting L1, L2, and L3 as landmarks, the practitioner is centered on the vertebral bodies that are directly related to the emergence of the thoracic and lumbar spinal nerves responsible for the sensory innervation to the flank and abdominal wall. These lumbar vertebrae are critical because they allow for adequate access to the paravertebral space where local anesthetic can be deposited effectively, providing analgesia for surgical procedures in the abdominal region.

In contrast, the other options involve either incorrect vertebral choices or landmarks that do not align with the proximal approach needed for effective blockage of the nerves. For instance, while T13, L1, and L2 (the second choice) also includes L1 and L2, T13 is not part of the lumbar vertebrae and does not relate to the necessary nerves when aiming to block at the proximal level. Therefore, focusing on L1, L2, and L3 optimally captures the region needed for the block.