How do our lungs expand as we breath?

Question

I always throught that ribs were constructed from bone and were solid, just like any other bone. If so, then how do they expand outwards when we breath out, then do the opposite when we breath in. Surely the ribs would snap? It's been puzzelling me for so many years!

Answer 1

The key to your question is joints and muscles.

Our ribs are connected mainly to the thoracic verterbrae and the sternum, these joints are synovial joints. For your information, synovial joints are joints which contained fluid to facilitate motion,in other words, those joints are pretty movable.

Also, main respiratory muscles such as the diaphragm, external and internal intercostal muscles allow the ribcage to expand in all directions.

Just imagine how the bucket handle works...when you pull it , the diameter actually increases.

Answer 2

http://faculty.etsu.edu/currie/ventilati...

The ribs are moved by muscle contraction -

Between the ribs are-  Intercostal muscles (costa = ribs):  

The external intercostals are involved in inspiration and the internal intercostals in expiration. When the external muscles contract, they pull the ribs closer together, elevating the ribcage, increasing thoracic volume, generating a more negative pressure in the intrapleural space and aiding in inspiration!  The internal muscles have the opposite effect.

Answer 3

the answer to this lies in the muscle that lies below the lungs, the diaphragm.  As this muscle pulls down the lungs expand and you inhale, and as the muscle pushes up the lungs contract and you exhale.