in·ter·cos·tal 
(ĭn′tər-kŏstəl)
(ĭn′tər-kŏstəl)adj.
Located or occurring between the ribs.
n.
A space, muscle, or part situated between the ribs.
[New Latin intercostālis : INTER- + Latin costa, rib; see kost- in the Appendix of Indo-European roots.]