Intercostal means, “between the ribs.”

According to Medline Plus, “The intercostal muscles are the muscles between the ribs. During breathing, these muscles normally tighten and pull the rib cage up.”

Machine Briefs:
Option #1: intercostal: INT/KOFLT
Option #2: intercostal: SBR-/KOFLT
Option #3: intercostal: INT/KOS/TAL
Option #4: intercostal: INT/KOFT/A*L
Option #5: intercostal: SBR-/KOFT/A*L
Option #6: intercostal: SBR-/KOS/TAL