• Muscles are only able to pull on bones, not push on them
• This means that there must be two sets of intercostal muscles; one to pull the rib cage up and another set to pull it down
• One set of intercostal muscles is found on the outside of the ribcage (the?external?intercostal muscles)
• The other set is found on the inside of the rib cage (the?internal?intercostal muscles)

There are 2 sets of intercostal muscles: the external, on the outside of the rib cage, and the internal, on the inside of the rib cage

轉載自savemyexams