Deep muscles of the thoracic wall

Deep muscles of the thoracic wall: Anatomy & FunctionAnatomy, function, blood supply and innervation of the deep muscles of the thoracic wall
~ 6 min

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

Borders of the chest region
Borders of the chest region

There are several anatomical regions within the chest:

  1. Mammary region (regio mammaria)

  2. Inframammary region (regio inframammaria)

  3. Sternal region (regio sternalis)

Anatomical chest regions
Anatomical chest regions

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)
    External intercostal muscles (mm. intercostales externi)
    External intercostal muscles (mm. intercostales externi)
    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)
    Internal intercostal muscles (mm. intercostales interni)
    Internal intercostal muscles (mm. intercostales interni)
    Internal intercostal muscles (mm. intercostales interni)
    Internal intercostal muscles (mm. intercostales interni)
    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)
    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)
    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)

Transversus thoracis muscle (m. transversus thoracis)
Transversus thoracis muscle (m. transversus thoracis)
Transversus thoracis muscle
(m. transversus thoracis)

Origin: posterior surface of the xiphoid process and the inferior part of the body of the sternum

Insertion: internal surface of the cartilages of the ribs 2-6

Function: lowers the ribs (participates in the act of inhalation)

Innervation: intercostal nerves (Th1-Th6)

Blood supply: internal thoracic artery

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.

Levatores costarum muscles
(mm. levatores costarum)

Origin: transverse processes of the C7-Th11 vertebrae

Insertion: superior margins of the underlying ribs

Function: lift the ribs, rotate the thoracic spine

Innervation: intercostal nerves (C3, Th1, Th2, Th6-Th10)

Blood supply: posterior intercostal arteries

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
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