Spinal Cord
The spinal cord extends the whole length of the vertebral canal and ends near the end of the tail as a thin, round thread. It varies in thickness and shape in cross section, being nearly always elliptical, but at places approaching a circle. Large, spindle-formed thickenings of about equal diameter are present in the cervical and lumbar regions.
A cauda equina is absent in the alligator, the nerves of the large tail leaving the cord like the intercostals.
On its ventral surface the cord has a deep perpendicular fissure, the fissura ventralis, that extends almost to the center; it extends even along the reduced region in the tail. A vascular membrane extends into this fissure.
A shallow but distinct furrow extends along the dorsal side of the cord, parallel to which, on either side, is a fine, linear furrow.
The first two spinal nerves have no dorsal roots.