Intercostal muscles

Intercostal muscle
Intercostal muscles highlighted in dark red.
Details
Origin	ribs 1-11
Insertion	ribs 2-12
Artery	intercostal arteries
Nerve	intercostal nerves
Actions	Elevation or Depression of the Ribs
Identifiers
Latin	Musculi intercostales
MeSH	A02.633.567.900.500
FMA	13354
Anatomical terms of muscle []

Intercostal muscles are several groups of muscles that run between the ribs, and help form and move the chest wall. The intercostal muscles are mainly involved in the mechanical aspect of breathing. These muscles help expand and shrink the size of the chest cavity to facilitate breathing.

There are three principal layers;

Both the external and internal muscles are innervated by the intercostal nerves (the ventral rami of thoracic spinal nerves), are supplied by the intercostal arteries, and are drained by the intercostal veins. Their fibers run in opposite directions.

The scalene muscles, which also move the chest wall and have a function in inhalation, are also intercostal muscles, just not one of the three principal layers.