internal
Diaphragm & interna intercostal muscle
intercostal muscle
Most important muscle of inspiration is the diaphragm, which upon contraction, pulls the base of the lung down and increases the pressure inside of the lung, drawing air into the lungs. Other muscles that are not as important except for in forced inspiration are the intercostal muscles and sternocleidomastoid muscles, which only work when forced expiration is required as well :)
The intercostal muscle area is located in the area surrounding the ribs. Intercostal muscle pain can be caused by overworking these muscles or by excessive coughing.
the intercostal muscle
Inspiration is due to the contraction of the diaphragm and external intercostal muscles.
Intercostal Muscles
Intercostal muscles are several groups of muscles that run between the ribs, and help form and move the chest wall. There are three principal layers; * the external intercostal muscles, which aid in quiet and forced inhalation. They originate on ribs 1-11 and have their insertion on ribs 2-12. The external intercostals are responsible for the elevation of the ribs, and expanding the transverse dimensions of the thoracic cavity. Located around the the ribs * the internal intercostal muscles, which aid in forced expiration (quiet expiration is a passive process). They originate on ribs 1-11 and have their insertions on ribs 2-12. The internal intercostals are responsible for the depression of the ribs decreasing the transverse dimensions of the thoracic cavity. * the innermost intercostal muscle Both the external and internal muscles are innervated by the intercostal nerves (the ventral rami of thoracic spinal nerves), and are provided by the intercostal arteries and intercostal veins. Their fibers run in opposite directions.
That is a good question. You have twelve intercostal nerves going between your ribs. They supply the intercostal muscles and carry back the sensations. You have the brachial plexus and lumbosacral plexuses. They are complicated as on today. But long back in evolution scale they were parallel. There complicated arrangement tells the the movement of muscle mass during evolution.
the intercostal muscles and the diaphragm
intercostal muscles
The main muscle used is the diaphragm. Also, the intercostal muscle.