Muscles of Respiration: Difference between revisions

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== Introduction  ==
== Introduction  ==
[[File:Overview of the respiratory system - Kenhub.png|alt=Overview of the respiratory system|right|frameless|600x600px|Overview of the respiratory system ]]
The muscles of respiration are also called the 'breathing pump muscles', they form a complex arrangement in the form of semi-rigid bellows around the [[Lung Anatomy|lungs]].


The muscles of respiration are also called the 'breathing pump muscles', they form a complex arrangement in the form of semirigid bellows around the lungs. All muscles that are attached to the human rib cage have the inherent potential to cause a breathing action. Muscles that helpful in expanding the thoracic cavity are called the inspiratory muscles because they help in inhalation, while those that compress the thoracic cavity are called expiratory muscles and they induce exhalation. These muscles possess exactly the same basic structure as all other skeletal muscles, and they work in concert to expand or compress the thoracic cavity.<ref name="strong">Breathe Strong, Perform Better by Alison McConnell http://www.humankinetics.com/excerpts/excerpts/learn-the-anatomy-and-physiology-of-the-muscles-involved-in-breathing</ref>
All [[Muscle|muscles]] that are attached to the human [[Ribs|rib]] cage have the inherent potential to cause a breathing action.  
 
# Muscles that are helpful in expanding the [[Thoracic Anatomy|thoracic]] cavity are called the inspiratory muscles because they help in inhalation.
# Those that compress the thoracic cavity are called expiratory muscles and they induce exhalation.  
 
These muscles possess exactly the same basic structure as all other [[Muscle Cells (Myocyte)|skeletal muscles]], and they work in concert to expand or compress the thoracic cavity.<ref name="strong">Breathe Strong, Perform Better by Alison McConnell http://www.humankinetics.com/excerpts/excerpts/learn-the-anatomy-and-physiology-of-the-muscles-involved-in-breathing</ref>
 
The speciality of these muscles are that they are composed of fatigue resistant muscle fibers, they are controlled by both voluntary and involuntary mechanisms (if we want to take a [[The Science of Breathing Well|breath]] we can, even if we do not think about breathing the body automatically does it)<ref name=":0">Pamela K. Levangie, Cynthia C. Norkin, 2005, Joint structure and function: A comprehensive analysis, 4th. Edn, Philadelphia, FA Davis publishers.</ref>
 
Image: Overview of the respiratory system<ref >Overview of the respiratory system image - © Kenhub https://www.kenhub.com/en/library/anatomy/the-respiratory-system</ref>


The speciality of these muscles are that they are composed of fatigue resistant muscle fibers, they are controlled by both voluntary and involuntary mechanisms (if we want to take a breath we can, even if we do not think about breathing the body automatically does it)<ref name=":0">Pamela K. Levangie, Cynthia C. Norkin, 2005, Joint structure and function: A comprehensive analysis, 4th. Edn, Philadelphia, FA Davis publishers.</ref>
<div class="row">
<div class="row">
   <div class="col-md-6"> {{#ev:youtube|mVLXqICrsdo|250}} <div class="text-right"><ref>AnatomyZone. Muscles of the Thoracic Wall - 3D Anatomy Tutorial. Available from: http://www.youtube.com/watch?v=mVLXqICrsdo[last accessed 12/4/2020]</ref></div></div>
   <div class="col-md-6"> {{#ev:youtube|mVLXqICrsdo|250}} <div class="text-right"><ref>AnatomyZone. Muscles of the Thoracic Wall - 3D Anatomy Tutorial. Available from: http://www.youtube.com/watch?v=mVLXqICrsdo[last accessed 12/4/2020]</ref></div></div>
   <div class="col-md-6"> {{#ev:youtube|GD-HPx_ZG8I|250}} <div class="text-right"><ref>Armando Hasudungan. Mechanism of Breathing. Available from: http://www.youtube.com/watch?v=GD-HPx_ZG8I[last accessed 12/4/2020]</ref></div></div>
   <div class="col-md-6"> {{#ev:youtube|GD-HPx_ZG8I|250}} <div class="text-right"><ref>Armando Hasudungan. Mechanism of Breathing. Available from: http://www.youtube.com/watch?v=GD-HPx_ZG8I[last accessed 12/4/2020]</ref></div></div>
== Primary Muscles  ==
</div>
==Primary Muscles  ==


The primary inspiratory muscles are the diaphragm and external intercostals. Relaxed normal expiration is a passive process, happens because of the elastic recoil of the lungs and surface tension. However there are a few muscles that help in forceful expiration and include the internal intercostals, intercostalis intimi, subcostals and the abdominal muscles.<ref name=":1">Musles of Respiration, Wikipedia page<nowiki/>https://en.wikipedia.org/wiki/Muscles_of_respiration (accessed 30 June 2018)</ref>
The primary inspiratory muscles are the '''diaphragm''' and '''external intercostals.''' Relaxed normal expiration is a passive process, happens because of the elastic recoil of the lungs and surface tension. However, there are a few muscles that help in forceful expiration and include the internal intercostals, intercostalis intimi, subcostals and the [[Abdominal Muscles|abdominal muscles]].<ref name=":1">Musles of Respiration, Wikipedia page<nowiki/>https://en.wikipedia.org/wiki/Muscles_of_respiration (accessed 30 June 2018)</ref>


The muscles of inspiration elevate the ribs and sternum, and the muscles of expiration depress them.<ref name="anatomy" />.  
The muscles of inspiration elevate the [[ribs]] and sternum, and the muscles of expiration depress them.<ref name="anatomy" />.  


== Accessory Muscles  ==
== Accessory Muscles  ==


The accessory inspiratory muscles are the [[sternocleidomastoid]], the scalenus anterior, medius, and posterior, the [[pectoralis major]] and [[Pectoralis Minor|minor]], the inferior fibres of serratus anterior and [[Latissimus Dorsi Muscle|latissimus dors]]<nowiki/>i, the [[Serratus posterior|serratus posterior superior]] may help in inspiration also the iliocostalis cervicis<ref name="anatomy">http://voiceandalexandertechnique.eu/voice-anatomy/pharynx-and-larynx/muscles-involved-in-voice-production/muscles-of-respiration.html</ref>. Technically any muscle attached to the upper limb and the thoracic cage can act as an accessory muscle of inspiration through reverse muscle action (muscle work from distal to proximal)<ref name=":0" />  
The accessory inspiratory muscles are the [[sternocleidomastoid]], the [[Scalene|scalenus]] anterior, medius, and posterior, the [[pectoralis major]] and [[Pectoralis Minor|minor]], the inferior fibres of [[Serratus Anterior|serratus anterior]] and [[Latissimus Dorsi Muscle|latissimus dors]]<nowiki/>i, the [[Serratus Posterior|serratus posterior superior]] may help in inspiration also the [[Iliocostalis Cervicis|iliocostalis cervicis]]<ref name="anatomy">http://voiceandalexandertechnique.eu/voice-anatomy/pharynx-and-larynx/muscles-involved-in-voice-production/muscles-of-respiration.html</ref>. Technically any muscle attached to the upper limb and the thoracic cage can act as an accessory muscle of inspiration through reverse muscle action (muscle work from distal to proximal)<ref name=":0" />


The accessory expiratory muscles are the abdominal muscles: rectus, abdominis, external oblique, internal oblique and transversus abdominis. And in the thoracolumbar region the lowest fibres of iliocostalis and longissimus, the [[Serratus posterior|serratus posterior inferior]] and quadratus lumborum.  
The accessory expiratory muscles are the [[Abdominal Muscles|abdominal muscles]]: [[Rectus Abdominis|rectus abdominis]], [[External Abdominal Oblique|external oblique]], [[Internal Abdominal Oblique|internal oblique]], and [[Transversus Abdominis|transversus abdominis]].


The accessory muscles are recruited during times of exercising because of the increased metabolic need and also during dysfunction in the respiratory system<ref name=":1" />
<div class="row"> 
<div class="col-md-2"> [[Image:Anterior abdominal wall deep muscles Primal.png|800px]]</div>
  <div class="col-md-2"> [[Image:Anterior abdominal wall superficial muscles Primal.png|800px]]</div>
  <div class="col-md-2"> [[Image:Anterior abdominal wall intermediate muscles Primal.png|800px]]</div>
</div>
And in the thoracolumbar region the lowest fibres of [[Iliocostalis Lumborum|iliocostalis]] and [[Longissimus Thoracis|longissimus]], the [[Serratus Posterior|serratus posterior inferior]] and [[Quadratus Lumborum|quadratus lumborum.]] The accessory muscles are recruited during times of exercising because of the increased metabolic need and also during dysfunction in the respiratory system<ref name=":1" />


[[Image:949 937 muscles-of-respiration.jpg]]
== Diaphragm ==
It's a double-domed musculotendinous sheet of internal skeletal muscle located at the inferior-most aspect of the rib cage that separates the thoracic cavity from the abdominal cavity.


=== Diaphragm ===
It serves two main functions:
[[File:Diaphragm (inferior view).jpeg|thumb|303x303px|Diaphragm(inferior view)]]
Origin: Xiphoid process (posterior surface), lower six ribs and their costal cartilage (inner surface) and upper three lumbar vertebrae as right crus and upper two lumbar vertebrae as left crus.


Insertion: central tendon
''-Separates the thoracic cavity from the abdominal cavity''


Nerve Supply: Motor nerve supply by Phrenic nerve (C3 C4 C5) and sensory supply by phrenic nerve to central tendon and lower 6 or 7 intercostal nerve to peripheral parts.<ref name="snell" />  
''-Undergoes contraction and relaxation, altering the volume of the thoracic cavity and the lungs, producing inspiration and expiration.''<ref name="snell" />[[File:Diaphragm (inferior view).jpeg|thumb|303x303px|Diaphragm(inferior view)|alt=|center]]
*Origin: Xiphoid process (posterior surface), lower six ribs and their costal cartilage (inner surface) and upper three lumbar vertebrae as right crus and upper two lumbar vertebrae as left crus.
*Insertion: central tendon
*Nerve Supply: Motor nerve supply by [[Phrenic Nerve|Phrenic nerve]] (C3 C4 C5) and sensory supply by phrenic nerve to central tendon and lower 6 or 7 intercostal nerve to peripheral parts.<ref name="snell" />
*Blood supply: inferior phrenic arteries deliver the majority of blood supply and the remaining supply is delivered via superior phrenic, musculophrenic and pericardiacophrenic arteries.
*Action: diaphragm is the main inspiratory muscle, during inspiration it contracts and moves in an inferior direction that increases the vertical diameter of the thoracic cavity and produces lung expansion, in turn, the air is drawn in.<ref>TeachMeAnatomy<nowiki/>https://teachmeanatomy.info/thorax/muscles/diaphragm/
</ref>
[[File:949_937_muscles-of-respiration.jpg|alt=|center|352x352px]]
== Intercostal muscles ==


=== Intercostal muscles ===
They are three types: External intercostal muscles (the most superficial muscle of intercostal muscles), internal intercostal muscles, and innermost intercostal muscles.


They are three types: External intercostal muscles, internal intercostal muscles, and innermost intercostal muscles.
==== '''External intercostal muscles''' ====
 
'''External intercostal muscles:'''  
*Origin: inferior border of rib above and  
*Origin: inferior border of rib above and  
*Insertion: superior border of rib below<br>  
*Insertion: superior border of rib below<br>  


'''Internal intercostal muscles:'''  
==== '''Internal intercostal muscles''' ====
*Origin: from the costal groove (lower part of inner surface of rib near the inferior border) of the rib above and  
* Origin: from the costal groove (lower part of inner surface of rib near the inferior border) of the rib above and
 
*Insertion: upper border of rib below<br>
*Insertion: upper border of rib below<br>


'''Innermost intercostal muscles:'''  
==== '''Innermost intercostal muscles:''' ====
*It is an incomplete muscle layer and crosses more than one intercostal space. These muscles assist in the function of external and internal intercostal muscles.  
It is an incomplete muscle layer and crosses more than one intercostal space. These muscles assist in the function of external and internal intercostal muscles.  
*Origin: from the costal groove of the rib above and  
*Origin: from the costal groove of the rib above and  
*Insertion: the superior border of rib below<br>
*Insertion: the superior border of rib below
 
*Nerve supply: all the intercostal muscles are supplied by their respective intercostal nerves.<ref name="snell">Snell's Clinical Anatomy http://teachinganatomy.blogspot.com/2013/07/respiratorymuscles.html</ref>
Nerve supply: all the intercostal muscles are supplied by their respective intercostal nerves.<ref name="snell">Snell's Clinical Anatomy http://teachinganatomy.blogspot.com/2013/07/respiratorymuscles.html</ref>
*Blood supply: all three muscles receive blood supply from anterior and posterior intercostal arteries, in addition to internal thoracic and musculophrenic arteries; costocervical trunk for internal and innermost intercostal muscles.<ref>KENHUB https://www.kenhub.com/en/library/anatomy/internal-intercostal-muscles</ref>


== References ==
== References ==

Latest revision as of 13:28, 9 April 2024

Introduction[edit | edit source]

Overview of the respiratory system

The muscles of respiration are also called the 'breathing pump muscles', they form a complex arrangement in the form of semi-rigid bellows around the lungs.

All muscles that are attached to the human rib cage have the inherent potential to cause a breathing action.

  1. Muscles that are helpful in expanding the thoracic cavity are called the inspiratory muscles because they help in inhalation.
  2. Those that compress the thoracic cavity are called expiratory muscles and they induce exhalation.

These muscles possess exactly the same basic structure as all other skeletal muscles, and they work in concert to expand or compress the thoracic cavity.[1]

The speciality of these muscles are that they are composed of fatigue resistant muscle fibers, they are controlled by both voluntary and involuntary mechanisms (if we want to take a breath we can, even if we do not think about breathing the body automatically does it)[2]

Image: Overview of the respiratory system[3]

Primary Muscles[edit | edit source]

The primary inspiratory muscles are the diaphragm and external intercostals. Relaxed normal expiration is a passive process, happens because of the elastic recoil of the lungs and surface tension. However, there are a few muscles that help in forceful expiration and include the internal intercostals, intercostalis intimi, subcostals and the abdominal muscles.[6]

The muscles of inspiration elevate the ribs and sternum, and the muscles of expiration depress them.[7].

Accessory Muscles[edit | edit source]

The accessory inspiratory muscles are the sternocleidomastoid, the scalenus anterior, medius, and posterior, the pectoralis major and minor, the inferior fibres of serratus anterior and latissimus dorsi, the serratus posterior superior may help in inspiration also the iliocostalis cervicis[7]. Technically any muscle attached to the upper limb and the thoracic cage can act as an accessory muscle of inspiration through reverse muscle action (muscle work from distal to proximal)[2]

The accessory expiratory muscles are the abdominal muscles: rectus abdominis, external oblique, internal oblique, and transversus abdominis.

Anterior abdominal wall deep muscles Primal.png
Anterior abdominal wall superficial muscles Primal.png
Anterior abdominal wall intermediate muscles Primal.png

And in the thoracolumbar region the lowest fibres of iliocostalis and longissimus, the serratus posterior inferior and quadratus lumborum. The accessory muscles are recruited during times of exercising because of the increased metabolic need and also during dysfunction in the respiratory system[6]

Diaphragm[edit | edit source]

It's a double-domed musculotendinous sheet of internal skeletal muscle located at the inferior-most aspect of the rib cage that separates the thoracic cavity from the abdominal cavity.

It serves two main functions:

-Separates the thoracic cavity from the abdominal cavity

-Undergoes contraction and relaxation, altering the volume of the thoracic cavity and the lungs, producing inspiration and expiration.[8]

Diaphragm(inferior view)
  • Origin: Xiphoid process (posterior surface), lower six ribs and their costal cartilage (inner surface) and upper three lumbar vertebrae as right crus and upper two lumbar vertebrae as left crus.
  • Insertion: central tendon
  • Nerve Supply: Motor nerve supply by Phrenic nerve (C3 C4 C5) and sensory supply by phrenic nerve to central tendon and lower 6 or 7 intercostal nerve to peripheral parts.[8]
  • Blood supply: inferior phrenic arteries deliver the majority of blood supply and the remaining supply is delivered via superior phrenic, musculophrenic and pericardiacophrenic arteries.
  • Action: diaphragm is the main inspiratory muscle, during inspiration it contracts and moves in an inferior direction that increases the vertical diameter of the thoracic cavity and produces lung expansion, in turn, the air is drawn in.[9]

Intercostal muscles[edit | edit source]

They are three types: External intercostal muscles (the most superficial muscle of intercostal muscles), internal intercostal muscles, and innermost intercostal muscles.

External intercostal muscles[edit | edit source]

  • Origin: inferior border of rib above and
  • Insertion: superior border of rib below

Internal intercostal muscles[edit | edit source]

  • Origin: from the costal groove (lower part of inner surface of rib near the inferior border) of the rib above and
  • Insertion: upper border of rib below

Innermost intercostal muscles:[edit | edit source]

It is an incomplete muscle layer and crosses more than one intercostal space. These muscles assist in the function of external and internal intercostal muscles.

  • Origin: from the costal groove of the rib above and
  • Insertion: the superior border of rib below
  • Nerve supply: all the intercostal muscles are supplied by their respective intercostal nerves.[8]
  • Blood supply: all three muscles receive blood supply from anterior and posterior intercostal arteries, in addition to internal thoracic and musculophrenic arteries; costocervical trunk for internal and innermost intercostal muscles.[10]

References[edit | edit source]

  1. Breathe Strong, Perform Better by Alison McConnell http://www.humankinetics.com/excerpts/excerpts/learn-the-anatomy-and-physiology-of-the-muscles-involved-in-breathing
  2. 2.0 2.1 Pamela K. Levangie, Cynthia C. Norkin, 2005, Joint structure and function: A comprehensive analysis, 4th. Edn, Philadelphia, FA Davis publishers.
  3. Overview of the respiratory system image - © Kenhub https://www.kenhub.com/en/library/anatomy/the-respiratory-system
  4. AnatomyZone. Muscles of the Thoracic Wall - 3D Anatomy Tutorial. Available from: http://www.youtube.com/watch?v=mVLXqICrsdo[last accessed 12/4/2020]
  5. Armando Hasudungan. Mechanism of Breathing. Available from: http://www.youtube.com/watch?v=GD-HPx_ZG8I[last accessed 12/4/2020]
  6. 6.0 6.1 Musles of Respiration, Wikipedia pagehttps://en.wikipedia.org/wiki/Muscles_of_respiration (accessed 30 June 2018)
  7. 7.0 7.1 http://voiceandalexandertechnique.eu/voice-anatomy/pharynx-and-larynx/muscles-involved-in-voice-production/muscles-of-respiration.html
  8. 8.0 8.1 8.2 Snell's Clinical Anatomy http://teachinganatomy.blogspot.com/2013/07/respiratorymuscles.html
  9. TeachMeAnatomyhttps://teachmeanatomy.info/thorax/muscles/diaphragm/
  10. KENHUB https://www.kenhub.com/en/library/anatomy/internal-intercostal-muscles