CIE IGCSE Biology: 复习笔记：11.1.6 Identifying Intercostal Muscles: Extended

• 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

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