main mountain range
Refers to the principal ridge or backbone of a mountain system.
The main range of this mountain system runs north-south.
midrib; costa
Botanical term for the central vein of a leaf; also used in medical contexts for rib-like structures.
main vein (leaf)
Specifically the primary vascular bundle in a leaf; synonymous with midrib in botany.
Lateral veins branch off from the main vein.
There is a cut along the midrib of the leaf.