IGCSEBiologyCambridge (CIE)Revision Notes11. Gas Exchange in HumansGas Exchange in HumansIdentifying Intercostal Muscles

Identifying Intercostal Muscles (Cambridge (CIE) IGCSE Biology): Revision Note

Exam code: 0610 & 0970

Written by: Lára Marie McIvor

Reviewed by: Jenna Quinn

Updated on 28 August 2026

Identifying intercostal muscles: Extended

Extended Tier Only

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 ribcage (the internal intercostal muscles)

Diagram of human thorax showing labelled lungs, bronchi, bronchioles, trachea, ribs, intercostal muscles (external on the outside and internal on the inside), pleural membranes, pleural fluid and diaphragm — **There are two sets of intercostal muscles: the external, on the outside of the ribcage, and the internal, on the inside of the ribcage**

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Author: Lára Marie McIvor

Expertise: Content Creator

Lára graduated from Oxford University in Biological Sciences and has now been a science tutor working in the UK for several years. Lára has a particular interest in the area of infectious disease and epidemiology, and enjoys creating original educational materials that develop confidence and facilitate learning.

Reviewer: Jenna Quinn

Expertise: Content Creator

Jenna studied at Cardiff University before training to become a science teacher at the University of Bath specialising in Biology (although she loves teaching all three sciences at GCSE level!). Teaching is her passion, and with 10 years experience teaching across a wide range of specifications – from GCSE and A Level Biology in the UK to IGCSE and IB Biology internationally – she knows what is required to pass those Biology exams.