Spinal cord anatomy, illustration. These transverse (axial) cross-sections of the spinal cord show the relative diameter, from near the brainstem (upper left), in the neck (cervical, upper centre), in the upper back (thoracic, upper right), in the lower back (lumbar, lower left), and in the sacrum (sacral, lower centre). The cross-section at lower right is at the end of the spinal column in the coccyx.