Logan Steele
The internal intercostal muscles are accessory respiratory muscles that are part of the thoracic wall, located in the intercostal spaces between the ribs. They are responsible for changing the volume of the thoracic cavity during respiration, specifically during exhalation. The internal intercostals originate from the costal groove of one rib and insert into the superior aspect of the rib below, depressing the ribs and reducing the thoracic volume to facilitate forced expiration.
| Characteristics | Values |
|---|---|
| Type | Muscle |
| Location | Intercostal spaces between the ribs |
| Function | Accessory respiratory muscles, aid forced expiration, depress the ribs, reduce the thoracic volume, support the integrity of the thoracic cage, change the volume of the thoracic cavity during respiration |
| Innervation | Intercostal nerves |
| Blood supply | Muscular branches of anterior and posterior intercostal arteries, intercostal branches of internal thoracic, musculophrenic arteries and costocervical trunk |
| Veins | Anterior and posterior intercostal veins |
| Number of muscles | 11 |
| Layers | Three (external, internal, and innermost) |
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What You'll Learn
Internal intercostals are accessory respiratory muscles
The internal intercostal muscles are accessory respiratory muscles that aid in forced exhalation, such as coughing or during exercise. They are part of the muscles of the thoracic wall, located in the intercostal spaces between the ribs. There are 11 internal intercostal muscles, filling each intercostal space by extending between the inferior margin of the superior rib to the superior margin of the rib below.
The internal intercostals originate from the costal groove of one rib and insert into the superior aspect of the rib below. They are innervated by the intercostal nerves of the corresponding intercostal spaces and receive their blood supply from the anterior and posterior intercostal arteries, as well as other blood vessels. The internal intercostal muscles work in conjunction with the external and innermost intercostal muscles to facilitate breathing.
The external intercostal muscles are the most superficial layer, originating from the inferior border of the rib above and inserting onto the superior border of the rib below. They contract during inspiration, raising the lateral part of the ribs and increasing the transverse diameter of the thorax. This expansion of the rib cage contributes to the inhalation process by reducing pressure within the lungs and allowing air to move into them.
In contrast, the internal intercostal muscles produce the opposite effect during exhalation. When these muscles contract, they pull down on the rib cage, lowering the ribs and reducing the anterior-posterior dimension. This action compresses the thoracic cavity and propels air out through the mouth and nose, facilitating forced exhalation.
The internal intercostal muscles are essential for normal speech and singing, as they control the propulsion of air during vocalisation. Their contraction creates clearly demarcated pulses, which are important for producing speech sounds. Overall, the internal intercostals play a crucial role in respiration by assisting with forced exhalation and supporting the respiratory process during vocalisation.
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They depress the ribs during forced exhalation
The internal intercostal muscles are a group of muscles that form the middle layer of the intercostal musculature. They are accessory respiratory muscles, which means they support the process of forced breathing. They are located deep to the external intercostals and are separated from them by a thin fascia.
The internal intercostal muscles play a crucial role in forced exhalation. During exhalation, the interosseous portions of these muscles depress and retract the ribs, reducing the volume of the thoracic cavity and facilitating the expulsion of air. This depression and retraction of the ribs occur from the superior border of one rib to the inferior border of the rib below. The internal intercostal muscles originate from the costal groove of the rib above and insert into the superior aspect of the rib below.
The internal intercostals are the major muscle group responsible for exhalation. They produce the opposite effect of the external intercostal muscles, which are responsible for inhalation. When the internal intercostals contract, they pull down on the rib cage, reducing the anterior-posterior dimension, and pushing air out of the lungs. This action is particularly important during forceful exhalation activities such as coughing or exercising, rather than relaxed breathing.
The internal intercostal muscles also work together with other muscles of the thoracic wall, including the external and innermost intercostals, subcostalis, and transversus thoracis. These muscles collectively change the volume of the thoracic cavity during respiration, ensuring the smooth intake and expulsion of air during breathing.
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They originate from the costal groove of one rib
The internal intercostal muscles are a group of muscles located in the thoracic wall, between the ribs. They are accessory respiratory muscles, aiding in forced expiration by depressing the ribs and reducing the volume of the thoracic cavity. The internal intercostal muscles originate from the costal groove of one rib and insert into the superior border of the rib below. This means that they attach to the rib above at the costal groove and extend to the rib below.
The internal intercostal muscles are one of three groups of intercostal muscles, along with the external and innermost intercostal muscles. These muscles work together to support the rib cage and facilitate respiration. The external intercostal muscles are the most superficial layer, originating from the inferior border of the rib above and inserting onto the superior border of the rib below. They elevate the ribs during inspiration, increasing the volume of the thoracic cavity.
The internal intercostal muscles, on the other hand, form the middle layer of the intercostal musculature. They originate from the lateral aspect of the costal groove of the rib above and course inferolaterally to attach to the superior border of the rib below. This arrangement allows them to depress the ribs during forced expiration, reducing the volume of the thoracic cavity. The internal intercostal muscles are innervated by the intercostal nerves and receive their blood supply from the anterior and posterior intercostal arteries, as well as other blood vessels.
The innermost intercostal muscles are the deepest layer of the thorax wall. They originate from the medial aspect of the costal groove of the rib above and insert onto the internal aspect of the rib below. These muscles are lined internally by the endothoracic fascia and are attached to the deep surfaces of adjacent ribs. The fibres of the innermost intercostal muscles lie deep to and run parallel with those of the internal intercostals.
Overall, the internal intercostal muscles play an important role in respiration, specifically during forced expiration. Their origin in the costal groove of one rib and insertion into the superior border of the rib below allow them to depress the ribs and reduce the volume of the thoracic cavity, facilitating the exhalation of air.
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They are innervated by the intercostal nerves
The internal intercostal muscles are a group of muscles that form the middle layer of the intercostal musculature. They are located in the intercostal spaces between the ribs, extending from the sternum anteriorly to the rib cage posteriorly. There are 11 internal intercostal muscles, filling each of the 11 intercostal spaces.
These muscles are innervated by the intercostal nerves of the corresponding intercostal spaces. The intercostal nerves are the anterior rami of the thoracic spinal nerves. They provide sensory and motor function to the internal intercostal muscles.
The intercostal nerves play a crucial role in the functioning of the internal intercostal muscles. They transmit signals that control the contraction and relaxation of these muscles during respiration. During forced expiration, such as coughing or exercise, the internal intercostal muscles contract, depressing the ribs and reducing the volume of the thoracic cavity. This contraction is facilitated by the intercostal nerves, which send signals to the muscles, causing them to contract in a coordinated manner.
Additionally, the intercostal nerves contribute to the sensory function of the internal intercostal muscles. They receive sensory input from various receptors within the muscles, providing information about the position and movement of the ribs during respiration. This sensory information helps regulate the activity of the internal intercostal muscles, ensuring proper breathing mechanics.
The innervation of the internal intercostal muscles by the intercostal nerves is essential for maintaining respiratory function. Damage to these nerves, such as through trauma or surgical procedures, can lead to respiratory impairments. Therefore, the intact functioning of the intercostal nerves is vital for the overall respiratory health and well-being of an individual.
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They are supplied by the anterior and posterior intercostal arteries
The internal intercostal muscles are a group of muscles that make up the thoracic wall, along with the external and innermost intercostals, subcostalis, and transversus thoracis. These muscles are located in the intercostal spaces between the ribs, with 11 internal intercostal muscles, as many as there are intercostal spaces. The internal intercostal muscles form the middle layer of the intercostal musculature, while the external intercostals form the most superficial layer, and the innermost intercostals form the deepest layer.
The internal intercostal muscles play a crucial role in respiration, specifically during forced exhalation. During exhalation, the interosseous portions of these muscles depress and retract the ribs, reducing the volume of the thoracic cavity and compressing it, which results in air being expelled. This action is particularly evident during forceful exhalation, such as coughing or exercising, rather than relaxed breathing. In contrast, the external intercostal muscles aid in inspiration by raising the ribs and expanding the thoracic cavity.
The internal intercostal muscles are innervated by the intercostal nerves of the corresponding intercostal spaces, which are the anterior rami of thoracic spinal nerves. Additionally, they receive their blood supply from several sources, including the muscular branches of the anterior and posterior intercostal arteries. These arteries provide oxygenated blood to the internal intercostal muscles, ensuring their proper functioning.
The anterior and posterior intercostal arteries play a vital role in supplying oxygenated blood to the internal intercostal muscles. These arteries branch off from the thoracic aorta and run along the intercostal spaces, supplying the intercostal muscles and the surrounding structures. The anterior intercostal arteries arise from the front of the aorta, while the posterior intercostal arteries originate from the back of the aorta. This dual blood supply ensures that the internal intercostal muscles receive adequate oxygenation and nutrition to support their role in respiration and maintenance of the thoracic cage.
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Frequently asked questions
Internal intercostal muscles are accessory respiratory muscles that aid forced expiration. They are located in the intercostal spaces between the ribs and make up the middle layer of the intercostal musculature.
The function of the internal intercostal muscles is to depress the ribs during forced expiration, thereby reducing the volume of the thoracic cavity and pushing air out of the lungs.
The external intercostal muscles are the most superficial layer of the intercostal muscles and originate from the inferior border of one rib, inserting onto the superior border of the rib below. They facilitate forced inspiration by elevating the ribs and expanding the thoracic cavity. In contrast, the internal intercostal muscles originate from the costal groove of one rib and insert onto the superior border of the rib below, depressing the ribs and reducing thoracic volume during forced expiration.
There are 11 pairs of internal intercostal muscles, with each muscle filling one intercostal space.
The internal intercostals are the most important respiratory muscles for normal speech and singing as they propel air out through the mouth and nose. The greater the pressure of the escaping air, the louder one's voice.
