This is the 17042nd most frequent Russian word.
спинной
"Spinal" or "related to the spine."
Here, 'спинной' refers to the 'spinal', indicating its relation to the spine.
Спинной мозг является важной частью нервной системы.
The spinal cord is an important part of the nervous system.
In this context, 'спинной' relates to the 'spinal area', describing the part of the body associated with the spine.
Он почувствовал боль в спинной области.
He felt pain in the spinal area.
Here, 'спинная' modifies 'поддержка', meaning it provides support for the spine or back.