At which level is the DRG largest?

The dorsal root ganglion (DRG) is a cluster of sensory neurons located just outside the spinal cord. Its size can vary depending on the level of the spinal column due to the density of sensory information being transmitted from different regions of the body.

At the lumbar levels, specifically L5, the DRG is typically the largest. This is because the lumbar region is responsible for innervating a significant portion of the lower limbs and pelvic region, leading to a higher number of sensory neurons that contribute to the DRG at this level. The lumbar nerves are crucial for transmitting sensory information from the legs and feet, which necessitates a larger ganglion to accommodate the increased volume of sensory input.

While the other levels mentioned may have notable sizes, they usually do not match the sheer number and density of sensory neurons found at L5, where the demand for sensory processing is greatest due to the extensive innervation of the lower body.