acantha

noun

1. A prickle.
2. A spine or prickly fin.
3. A spinous process of a vertebra.

   “Moreover, all the outgrowths which I have said constitute the acantha are not of equal size in all the vertebrae, and Nature has done this with wonderful forethought.”

   “Individual vertebral bodies (right) as seen from the side and from above. The acantha is the spiney projection on the right of each illustration: in the lower illustration the boney spinal canal is shown between the acantha and the vertebral body.”

   “Rotary strokes or stationary circles in the direction of the flank / Alternate from the acantha of the vertebral column in the direction of the flank (medial to lateral)”