What is foraminal narrowing and ventral thecal sac indentation? i also have osteoarthritis in my back alon with nerve pain in both legs

Vocabulary list: A foramina is an opening or hole--as you are using, usually where a spinal nerve (/"nerve root") exits to left or right of spinal column, and it is slowly closing down, possibly from arthritic calcification (=may need surgery in future). Ventral is underside (towards abdomen, not back/dorsal), t-sac surrounds cord--not severe w/o cord compression. The above "could" be pain link. Ask spine dr.

Spinal stenosis: Possible cause. Arthritis underlying it- narrowing foramina means nerves leading down legs are being compressed ;'irritated- sciatica should be followed by your pcp ; orthopedist.