Innermost intercostal muscle

Innermost intercostal muscle
Innermost intercostal muscle (red), seen from back.
Details
Origin	Infero-posterior border of each rib (above)
Insertion	Supero-posterior border of the rib (below)
Artery	intercostal arteries
Nerve	intercostal nerves
Actions	Through adduction of upper ribs to the lower ribs the muscles narrow intercostal slits and diminish thorax volume, therefore the muscles represent expiratory muscles.
Identifiers
Latin	musculus intercostalis intimus
TA	A04.4.01.014
FMA	74086
Anatomical terms of muscle [edit on Wikidata]

The innermost intercostal muscle is a layer of intercostal muscles deep to the plane that contains the intercostal nerves and intercostal vessels and the internal intercostal muscles. These are divided into:

1. transversus thoracis anteriorly
2. lateral muscle slips laterally (which cross a single intercostal space)
3. subcostalis posteriorly (which often cross more than one intercostal space)

Additional images

• 
  Innermost intercostal muscle (shown in red). Animation.
• 
  A cutout of the thoracic wall showing the three layers of intercostal muscle - from the left wall.

External links

• Anatomy photo:18:04-0103 at the SUNY Downstate Medical Center - "Thoracic Wall: The Intercostal Nerve and Vessels"
• Anatomy figure: 18:03-04 at Human Anatomy Online, SUNY Downstate Medical Center - "Transverse section of thorax."
• -301596595 at GPnotebook
• thoraxmuscles at The Anatomy Lesson by Wesley Norman (Georgetown University)