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The intercostal muscles are a group of intrinsic rib cage muscles that occupy the 11 intercostal spaces between the ribs. They are divided into three groups: external, internal, and innermost intercostals. These muscles are primarily responsible for changing the volume of the thoracic cavity during respiration. The external intercostals are the outermost layer, lying directly under the skin and wrapping around from the back of the rib almost to the end of the bony part of the rib in front. The internal intercostals form the middle layer and originate from the costal groove of one rib. The innermost intercostals are the deepest intercostal muscles and assist the internal and external intercostals in their function.
| Characteristics | Values |
|---|---|
| Definition | Group of intrinsic rib cage muscles that occupy the 11 intercostal spaces |
| Number of layers | 3 |
| Types of layers | External, Internal, Innermost |
| Function | Support the rib cage and participate in the process of forced breathing |
| External intercostals function | Facilitate forced inspiration |
| Internal and innermost intercostals function | Aid forced expiration |
| Innervation | Intercostal nerves |
| Blood supply | Anterior and posterior intercostal arteries, costocervical trunk, internal thoracic and musculophrenic arteries |
| Strain causes | Weakened muscles, overexertion, direct trauma, repetitive torso twisting |
| Strain symptoms | Worsening pain, difficulty breathing, tenderness, inflammation |
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What You'll Learn
Intercostal muscles are found within the rib cage
Intercostal muscles are a group of intrinsic muscles that occupy the 11 intercostal spaces within the rib cage. They are divided into three groups: external, internal, and innermost intercostals. These muscles support the rib cage and participate in the process of forced breathing. The external intercostals are the most superficial muscles, originating from the inferior border of one rib and inserting into the superior border of the rib below. They facilitate forced inspiration during breathing.
The internal intercostals form the middle layer of the intercostal musculature. They originate from the costal groove of one rib and insert into the superior border of the rib below. They function to depress the ribs during forced expiration. The innermost intercostals are the deepest intercostal muscles, crossing more than one intercostal space and assisting the internal and external intercostals in their functions.
The intercostal muscles work together to change the volume of the thoracic cavity during respiration. During inspiration, the external intercostals contract and raise the lateral part of the ribs, increasing the transverse diameter of the thorax. The internal intercostals, on the other hand, help collapse the lungs during expiration by depressing the ribs and reducing thoracic volume.
The intercostal muscles are thin sheets of muscular fibres that run between the ribs in the costal spaces. They consist of two layers of muscle fibres in the lateral portion of the intercostal spaces, with a single muscle layer in the ventral and dorsal portions. The internal intercostals are particularly thick in the region of the rib cage near the sternum and are known as the parasternal intercostals.
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They support the rib cage and aid forced breathing
Intercostal muscles are a group of intrinsic rib cage muscles that occupy the 11 intercostal spaces between the ribs. They are divided into three groups, from superficial to deep: external, internal, and innermost. All three groups of muscles support the rib cage and are accessory respiratory muscles that participate in the process of forced breathing.
The external intercostals are the most superficial intercostal muscles. They originate from the inferior border of one rib and insert into the superior border of the rib below. During inspiration, the external intercostals contract and raise the lateral part of the ribs, increasing the transverse diameter of the thorax. This facilitates forced inspiration.
The internal intercostals form the middle layer of the intercostal musculature. They originate from the costal groove of one rib and insert into the superior border of the rib below. They depress the ribs and decrease the thoracic volume during forced expiration.
The innermost intercostals are the deepest intercostal muscles. They originate from the medial aspect of the costal groove of the rib above and insert into the internal aspect of the rib below. They assist the internal and external intercostals in their functions.
Together, the three layers of intercostal muscles support the rib cage and aid in forced breathing by facilitating inspiration and expiration. They work in conjunction with other muscles that attach to the thoracic wall, such as the pectoralis major and minor, to enable respiration and maintain the stability of the rib cage during normal and forced breathing.
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Intercostal muscles are divided into three layers
Intercostal muscles are a group of intrinsic rib cage muscles that occupy the 11 intercostal spaces between the ribs. They are involved in the mechanical aspect of breathing by helping to expand and shrink the chest cavity.
The intercostal muscles are divided into three layers, or groups, of muscles: the external, internal, and innermost intercostal muscles. The external intercostals are the outermost layer and lie directly under the skin. They originate from the inferior border of one rib, course inferomedially, and insert into the superior border of the rib below. They are responsible for forced inspiration, as they expand the chest wall during inhalation.
The internal intercostals form the middle layer of the intercostal musculature. They originate from the costal groove of one rib, course inferolaterally, and insert into the superior border of the rib below. They are innervated by the intercostal nerves and receive blood supply from various arteries. The internal intercostals depress the ribs during forced expiration, helping to collapse the lungs.
The innermost intercostals are the deepest layer of intercostal muscles. They cross more than one intercostal space and assist the internal and external intercostals in their functions. All three layers of intercostal muscles support the rib cage and participate in the process of forced breathing.
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Intercostal muscle strain can be caused by trauma or overexertion
Intercostal muscles are the muscles that link the ribs together. They are part of the ribcage and help with breathing by changing the size of the space inside the ribcage. Intercostal muscle strain refers to an injury affecting the muscles between two or more ribs. This type of injury often results from overexertion or trauma.
Overexertion can cause intercostal muscle strain. A sudden increase in physical activity can lead to this type of strain, especially when a lack of exercise or poor posture has resulted in weaker muscles. Twisting while lifting weights, prolonged overhead reaching, and rowing or swimming for extended periods are examples of overexertion that can cause intercostal muscle strain.
Trauma can also cause intercostal muscle strain. A direct blow to the ribs, fall, or automobile accident can result in this type of injury. In addition, a severe injury that weakens the upper spine, such as a car accident, can also cause intercostal muscle strain.
The symptoms of intercostal muscle strain include sharp, direct pain, stiffness, and mobility difficulties. The pain may worsen gradually after repetitive movements such as rowing, swimming, or other physical exercises. Stiffness and tension in the muscles can cause upper back pain.
It is important to see a doctor if the pain from an intercostal muscle strain is severe, lasts for several days, or interferes with sleep or daily activities. Immediate medical attention is necessary if a traumatic injury has occurred, breathing is difficult, or the patient is coughing up blood.
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Intercostal muscles are innervated by intercostal nerves
Intercostal muscles are a group of intrinsic rib cage muscles that occupy the 11 intercostal spaces between the ribs. They are divided into three groups: external, internal, and innermost intercostal muscles. The external intercostals are the most superficial intercostal muscles, originating from the inferior border of one rib and inserting into the superior border of the rib below. They are responsible for elevating the ribs during forced inspiration, thereby aiding in inhalation. The internal intercostals form the middle layer of the intercostal musculature. They originate from the costal groove of one rib and insert into the superior border of the rib below, helping to depress the ribs during forced expiration. The innermost intercostals are the deepest intercostal muscles, crossing more than one intercostal space and assisting the internal and external intercostals in their functions.
The intercostal muscles are innervated by the intercostal nerves. Specifically, the external intercostal muscles are innervated by the anterior rami of spinal nerves T1-T11, which are the intercostal nerves of the corresponding intercostal space. The internal intercostal muscles are innervated in the same way as the external intercostals, by the intercostal nerves. The innermost intercostals follow the same innervation pattern as the internal intercostals.
Lesions of the intercostal nerves, such as those caused by trauma or surgical procedures, can result in a "strip-like" paresthesia. Intercostal muscle strains can occur due to weakened muscles, overexertion, direct trauma, or repetitive torso twisting. These strains can lead to pain, inflammation, and difficulty breathing. The healing process for intercostal strains can vary from a few days to 8 weeks or longer, depending on the severity of the injury.
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Frequently asked questions
Intercostal muscles are a group of intrinsic rib cage muscles that occupy the 11 intercostal spaces. They are divided into three groups: external, internal, and innermost intercostals.
Intercostal muscles support the rib cage and are accessory respiratory muscles that participate in the process of forced breathing. The external intercostals facilitate forced inspiration, while the internal and innermost intercostals aid forced expiration.
The external intercostals contract and raise the lateral part of the ribs, increasing the transverse diameter of the thorax. The internal intercostals depress the ribs and decrease the thoracic volume during forced expiration.
An intercostal muscle strain occurs when the muscles are weakened, overexerted, or experience direct trauma such as a blow to the rib cage or twisting the torso. Symptoms include pain, difficulty breathing, tenderness, and inflammation.
