This is the group of muscles between each rib. The group (from posterior to anterior) consists of: innermost m, internal m and external m. All 3 muscles are innervated by the intercostal nerve. The intercostal vascular bundle travels between the innermost and internal mm.

  1. external IC m- elevates ribs during forced inspiration
  2. internal IC m- depresses ribs during forced respiration
  3. innermost IC m- elevates ribs during forced respiration