The term spine is c. 1400, "backbone," later "thornlike part" (early 15c.), from Old French espine "thorn, prickle; backbone, spine" (12c., Modern French épine), from Latin spina "backbone," originally "thorn, prickle" (figuratively, in plural, "difficulties, perplexities.")
The spine in a body and the spine in a play holds the entity in place. Without a strong spine the entity will collapse. What is the spine of your business? What holds together the entity? The spine of a business starts in a business plan and expands from the plan. Keep a strong spine for a strong entity.
Trodden on journeys, pathways to the inner self, deep in the grasses