In the previous pdf-note, we have learned about the superficial muscles of the chest. In this pdf-note, we will learn more about the deep muscles of the chest.

As discussed in the previous pdf-notes, the chest region has the following borders:

• The superior border passes through the jugular notch of the sternum, superior border of the clavicle, and acromioclavicular joint

• The inferior border passes through the xiphoid process of the sternum and the costal arch

• The lateral border is the posterior median line

There are several anatomical regions within the chest:

1. Mammary region (regio mammaria)

2. Inframammary region (regio inframammaria)

3. Sternal region (regio sternalis)

The muscles of the chest are located within these regions. The deep muscles of the chest include:

• External intercostal muscles (mm. intercostales externi)

  

  

  External intercostal muscles
  (mm. intercostales externi)

  Origin: inferior margins of the superposed ribs

  Insertion: superior margins of the underlying ribs

  Function: lift the ribs during forced inhalation, support the intercostal spaces and thoracic cage

  Innervation: intercostal nerves (Th1-Th11)

  Blood supply: posterior intercostal arteries, internal thoracic artery (anterior intercostal branches), musculophrenic artery

• Internal intercostal muscles (mm. intercostales interni)

  

  

  

  Internal intercostal muscles
  (mm. intercostales interni)

  Origin: superior margins of the underlying ribs

  Insertion: inferior margins of the superposed ribs

  Function: lower the ribs during forced exhalation, support the intercostal spaces and thoracic cage

  Innervation: intercostal nerves (Th1-Th11)

  Blood supply: posterior intercostal arteries, internal thoracic artery (anterior intercostal branches), musculophrenic artery

• Innermost intercostal muscles (mm. intercostales intimi)

  

  Innermost intercostal muscles
  (mm. intercostales intimi)

  Origin: superior margins of the underlying ribs

  Insertion: inferior margins of the superposed ribs

  Function: ower the ribs during forced exhalation, support the intercostal spaces and thoracic cage

  Innervation: intercostal nerves (Th1-Th11)

  Blood supply: posterior intercostal arteries, internal thoracic artery (anterior intercostal branches), musculophrenic artery

• Subcostales muscles (mm. subcostales)

  

  Subcostales muscles
  (mm. subcostales)

  Origin: internal surface of the rib at the angle region

  Insertion: internal surface of the superposed ribs (through 1-2-3)

  Function: lower the ribs during forced exhalation, support the intercostal spaces and thoracic cage

  Innervation: intercostal nerves (Th1-Th11)

  Blood supply: posterior intercostal arteries

• Transversus thoracis muscle (m. transversus thoracis)

Sometimes the muscles of the chest also include the muscles that lift the ribs (mm. levatores costarum). Although according to the embryological classification they fit better into the group of the muscles of the back.

Dictionary

Muscles of the thoracic wall

Mammary region

regio mammaria

Inframammary region

regio inframammaria

Sternal region

regio sternalis

External intercostal muscles

mm. intercostales externi

Internal intercostal muscles

mm. intercostales interni

Innermost intercostal muscles

mm. intercostales intimi

Subcostales muscles

mm. subcostales

Transversus thoracis muscle

m. transversus thoracis

Levatores costarum muscles

mm. levatores costarum