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Action of the Respiratory Muscles

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Abstract

The sections in this article are:

1 Diaphragm
1.1 Functional Anatomy of the Diaphragm
1.2 Action of the Diaphragm
2 Consequences of Diaphragmatic Contraction
2.1 Diaphragm: Two Muscles
3 Muscles of The Rib Cage
3.1 Functional Anatomy of the Rib Cage
3.2 Intercostal Muscles
3.3 Accessory Muscles
3.4 Rib Cage Shape and Distortion
4 Abdominal Muscles
4.1 Functional Anatomy of Abdominal Muscles
4.2 Action of Abdominal Muscles
Figure 1. Figure 1.

Functional anatomy of the diaphragm. A app, zone of apposition of the diaphragm to the rib cage.

Figure 2. Figure 2.

Spirometric record (top) and electromyographic activity of the left hemidiaphragm (bottom) recorded with bipolar clip electrodes in a dog breathing quietly. After bilateral phrenicotomy, some activity is still recorded from the diaphragm, especially during the expiratory pause. This activity disappears after a plastic sheet has been placed in the zone of apposition to insulate the diaphragm from the rib cage muscles. Electrocardiogram appears on the records.

Figure 3. Figure 3.

Abdomen and rib cage motion (anteroposterior diameters) at the level of the 7th rib (left) and the 3rd rib (right) during quiet breathing in a tetraplegic human in seated position. Gains on anteroposterior rib cage and abdominal diameters adjusted so that the isovolume maneuver gives a slope of −1. Broken lines represent the relaxation characteristics of the respiratory system; solid loops represent tidal volume cycles. Arrows indicate direction of the loops; small horizontal lines mark the end of inspiration.

Adapted from Mortola and Sant'Ambrogio
Figure 4. Figure 4.

Abdomen and lower rib cage motion (anteroposterior diameters) during quiet breathing in a tetraplegic subject in seated (left) and supine (right) position. Broken lines represent the relaxation characteristics; solid loops represent tidal volume cycles. Arrows indicate direction of the loops; small horizontal lines mark the end of inspiration.

Adapted from Danon et al.
Figure 5. Figure 5.

Effects of separate stimulation of the costal and crural parts of the diaphragm on the thoracoabdominal configuration in a supine dog. Rib cage dimension refers to the lower rib cage at the level of the xyphoid process. Calibration of the signals done so that an isovolume maneuver gives a deflection of −1. Left: abdomen is closed and abdominal pressure increases during diaphragmatic stimulation. Right: abdomen is open so that the increase in abdominal pressure during stimulation is small and the appositional component of diaphragm's action is almost suppressed.

From De Troyer et al.
Figure 6. Figure 6.

Mechanical model of inspiratory muscle action in which the diaphragm is represented as two sets of muscles corresponding to the costal and crural parts. Hatched areas represent fixed structures; inverted U‐shaped bar represents the rib cage; horizontal bar represents the central tendon. Spring between the rib cage and fixed structures represents the elastic properties of the rib cage; spring between the rib cage and the central tendon represents the elastic properties of the lung; spring between the central tendon and other fixed structures represents the elastic properties of the abdomen.

Figure 7. Figure 7.

Left lateral projection of the mechanical model shown in Fig. . Same legend as in Fig. . Hatched areas are the bony structures other than the rib cage; inverted L‐shaped bar represents the rib cage that is attached to the vertebral column by a hinge. Right: a more anatomically realistic drawing of the diaphragm illustrating the separation of costal and crural parts.

Adapted from Macklem et al.
Figure 8. Figure 8.

Segmental innervation of the diaphragm in the dog. Top to bottom: tidal volume, electrical activity of the anterior portion of the costal diaphragm, electrical activity of the posterior portion of the costal diaphragm, and electrical activity of the crural portion of the right hemidiaphragm during separate stimulation of the right fifth (C5), sixth (C6), and seventh (C7) cervical roots in the neck. Time scale = 1 s. [From De Troyer et al. .1

Figure 9. Figure 9.

Functional anatomy of the human rib cage. Left: frontal angle of inclination of the axes of the necks of ribs 1 and 6. Right: diagrams of pump‐handle and bucket‐handle inspiratory movements. In the upper ribs, rotation of the rib‐neck axis raises the sternal end of the ribs and increases the anteroposterior diameter of the rib cage (pump‐handle motion). In the lower ribs, movement at the costovertebral joints elevates the lateral part of the ribs and increases the lateral diameter of the rib cage (bucket‐handle motion).

Adapted from Gray's Anatomy
Figure 10. Figure 10.

Changes in abdomen and rib cage cross section during quiet breathing in a supine anesthetized dog before and after bilateral phrenicotomy. The gains on the rib cage and abdominal dimensions adjusted so that the isovolume lines have a slope of approximately −1. Broken line represents relaxation characteristics of the chest wall; solid loops represent tidal volume cycles. Arrows indicate direction of the loops.

From De Troyer and Kelly
Figure 11. Figure 11.

Left: anteroposterior abdominal and rib cage diameters during quiet breathing in a human breathing only with the sternocleidomastoids and the trapezius muscles. Diameters adjusted to volume equivalency using the isovolume maneuver. Right: anteroposterior and lateral diameters of the rib cage plotted against each other; their gains adjusted so that the relaxation curve has a slope of +1. Contraction of the sternocleidomastoids and the trapezius muscles causes an increase only in the anteroposterior diameter of the rib cage; both the abdominal anteroposterior and the rib cage lateral diameters decrease during inspiration.

Adapted from Danon et al.
Figure 12. Figure 12.

Behavior of the lower and upper parts of the rib cage (cross‐sectional areas) in a tetraplegic human during the course of a maximal inspiration from functional residual capacity (open circle). Arrows indicate direction of the loop; small vertical line marks the end of inspiration.

From Urmey et al.
Figure 13. Figure 13.

Individual actions of the abdominal muscles on the lower rib cage in supine anesthetized dogs. In each panel, the gain on the rib cage transverse diameter is adjusted so that its deflection is identical to that obtained for the rib cage anteroposterior diameter (slope of +1) during relaxation (dashed line). Open squares represent the rib cage configuration at functional residual capacity; closed circles correspond to the deflections obtained with the abdomen closed; open circles correspond to the deflections obtained for the same stimulation with the abdomen open.

From De Troyer et al.
Figure 14. Figure 14.

Tonic (postural) activity in the abdominal muscles in 3 postures during tilting. Activity is recorded with needle electrodes from the upper and lower parts of the external oblique in a normal human. The gains of the 2 electromyographic (EMG) signals are adjusted to give equal amount of activity during an expulsive maneuver.



Figure 1.

Functional anatomy of the diaphragm. A app, zone of apposition of the diaphragm to the rib cage.



Figure 2.

Spirometric record (top) and electromyographic activity of the left hemidiaphragm (bottom) recorded with bipolar clip electrodes in a dog breathing quietly. After bilateral phrenicotomy, some activity is still recorded from the diaphragm, especially during the expiratory pause. This activity disappears after a plastic sheet has been placed in the zone of apposition to insulate the diaphragm from the rib cage muscles. Electrocardiogram appears on the records.



Figure 3.

Abdomen and rib cage motion (anteroposterior diameters) at the level of the 7th rib (left) and the 3rd rib (right) during quiet breathing in a tetraplegic human in seated position. Gains on anteroposterior rib cage and abdominal diameters adjusted so that the isovolume maneuver gives a slope of −1. Broken lines represent the relaxation characteristics of the respiratory system; solid loops represent tidal volume cycles. Arrows indicate direction of the loops; small horizontal lines mark the end of inspiration.

Adapted from Mortola and Sant'Ambrogio


Figure 4.

Abdomen and lower rib cage motion (anteroposterior diameters) during quiet breathing in a tetraplegic subject in seated (left) and supine (right) position. Broken lines represent the relaxation characteristics; solid loops represent tidal volume cycles. Arrows indicate direction of the loops; small horizontal lines mark the end of inspiration.

Adapted from Danon et al.


Figure 5.

Effects of separate stimulation of the costal and crural parts of the diaphragm on the thoracoabdominal configuration in a supine dog. Rib cage dimension refers to the lower rib cage at the level of the xyphoid process. Calibration of the signals done so that an isovolume maneuver gives a deflection of −1. Left: abdomen is closed and abdominal pressure increases during diaphragmatic stimulation. Right: abdomen is open so that the increase in abdominal pressure during stimulation is small and the appositional component of diaphragm's action is almost suppressed.

From De Troyer et al.


Figure 6.

Mechanical model of inspiratory muscle action in which the diaphragm is represented as two sets of muscles corresponding to the costal and crural parts. Hatched areas represent fixed structures; inverted U‐shaped bar represents the rib cage; horizontal bar represents the central tendon. Spring between the rib cage and fixed structures represents the elastic properties of the rib cage; spring between the rib cage and the central tendon represents the elastic properties of the lung; spring between the central tendon and other fixed structures represents the elastic properties of the abdomen.



Figure 7.

Left lateral projection of the mechanical model shown in Fig. . Same legend as in Fig. . Hatched areas are the bony structures other than the rib cage; inverted L‐shaped bar represents the rib cage that is attached to the vertebral column by a hinge. Right: a more anatomically realistic drawing of the diaphragm illustrating the separation of costal and crural parts.

Adapted from Macklem et al.


Figure 8.

Segmental innervation of the diaphragm in the dog. Top to bottom: tidal volume, electrical activity of the anterior portion of the costal diaphragm, electrical activity of the posterior portion of the costal diaphragm, and electrical activity of the crural portion of the right hemidiaphragm during separate stimulation of the right fifth (C5), sixth (C6), and seventh (C7) cervical roots in the neck. Time scale = 1 s. [From De Troyer et al. .1



Figure 9.

Functional anatomy of the human rib cage. Left: frontal angle of inclination of the axes of the necks of ribs 1 and 6. Right: diagrams of pump‐handle and bucket‐handle inspiratory movements. In the upper ribs, rotation of the rib‐neck axis raises the sternal end of the ribs and increases the anteroposterior diameter of the rib cage (pump‐handle motion). In the lower ribs, movement at the costovertebral joints elevates the lateral part of the ribs and increases the lateral diameter of the rib cage (bucket‐handle motion).

Adapted from Gray's Anatomy


Figure 10.

Changes in abdomen and rib cage cross section during quiet breathing in a supine anesthetized dog before and after bilateral phrenicotomy. The gains on the rib cage and abdominal dimensions adjusted so that the isovolume lines have a slope of approximately −1. Broken line represents relaxation characteristics of the chest wall; solid loops represent tidal volume cycles. Arrows indicate direction of the loops.

From De Troyer and Kelly


Figure 11.

Left: anteroposterior abdominal and rib cage diameters during quiet breathing in a human breathing only with the sternocleidomastoids and the trapezius muscles. Diameters adjusted to volume equivalency using the isovolume maneuver. Right: anteroposterior and lateral diameters of the rib cage plotted against each other; their gains adjusted so that the relaxation curve has a slope of +1. Contraction of the sternocleidomastoids and the trapezius muscles causes an increase only in the anteroposterior diameter of the rib cage; both the abdominal anteroposterior and the rib cage lateral diameters decrease during inspiration.

Adapted from Danon et al.


Figure 12.

Behavior of the lower and upper parts of the rib cage (cross‐sectional areas) in a tetraplegic human during the course of a maximal inspiration from functional residual capacity (open circle). Arrows indicate direction of the loop; small vertical line marks the end of inspiration.

From Urmey et al.


Figure 13.

Individual actions of the abdominal muscles on the lower rib cage in supine anesthetized dogs. In each panel, the gain on the rib cage transverse diameter is adjusted so that its deflection is identical to that obtained for the rib cage anteroposterior diameter (slope of +1) during relaxation (dashed line). Open squares represent the rib cage configuration at functional residual capacity; closed circles correspond to the deflections obtained with the abdomen closed; open circles correspond to the deflections obtained for the same stimulation with the abdomen open.

From De Troyer et al.


Figure 14.

Tonic (postural) activity in the abdominal muscles in 3 postures during tilting. Activity is recorded with needle electrodes from the upper and lower parts of the external oblique in a normal human. The gains of the 2 electromyographic (EMG) signals are adjusted to give equal amount of activity during an expulsive maneuver.

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How to Cite

André de Troyer, Stephen H. Loring. Action of the Respiratory Muscles. Compr Physiol 2011, Supplement 12: Handbook of Physiology, The Respiratory System, Mechanics of Breathing: 443-461. First published in print 1986. doi: 10.1002/cphy.cp030326