Vertebral location of cord segments innervating cat hind limb musculature

To facilitate future studies requiring efficient surgical access to spinal cord segments innervating cat hind limb muscles, lumbosacral cord segments L3 through S2 were located with reference to the dorsolateral tips of the rostral articular processes of the surrounding vertebrae. A map showing means and ranges of vertebral loci of these segments from 20 cats was constructed. Correlation analysis was then used to find a practical way of narrowing the predicted range of loci of segments supplying the lower hind limb muscles in a particular cat. Several of the midlumbar junctions were determined to be good predictors of the position of the S2-S3 junction, the caudal limit of hind limb innervation. However, L4-L5 was found to be the most feasible to use experimentally, because of the ease of exposing and identifying it. Because all of the lumbosacral segments L3 through S2 in a given cat show a similar tendency with regard to relative length, the positions of the segments L6 through S1 can be interpolated from the prediction of the S2-S3 junction.