Intercostal muscles

Intercostal muscles are a group of muscles situated in the intercostal spaces between the ribs. They are primarily involved in the mechanical aspect of breathing, including inhalation and exhalation. There are three layers of intercostal muscles: the external intercostal muscles, the internal intercostal muscles, and the innermost intercostal muscles.

Anatomy

The external intercostal muscles are the most superficial, lying just under the skin and the subcutaneous fascia. They originate from the lower border of each rib and insert into the upper border of the rib below. Their fibers run obliquely downward and forward from the back of the chest to the front.

The internal intercostal muscles lie deep to the external intercostal muscles. They originate from the lower border of each rib and insert into the upper border of the rib below. Their fibers run obliquely downward and backward from the front of the chest to the back.

The innermost intercostal muscles are the deepest layer. They are separated from the internal intercostal muscles by the intercostal nerves and vessels. Their fibers run in the same direction as those of the internal intercostal muscles.

Function

The intercostal muscles play a crucial role in the mechanics of breathing. The external intercostal muscles aid in inspiration by elevating the ribs, thus increasing the volume of the thoracic cavity. The internal and innermost intercostal muscles aid in expiration by depressing the ribs, thus decreasing the volume of the thoracic cavity.

Clinical significance

Damage or injury to the intercostal muscles can lead to various conditions such as intercostal neuralgia, a condition characterized by pain in the chest wall due to irritation or damage to the intercostal nerves. Other conditions include intercostal strain, which is an injury to the intercostal muscles caused by strenuous activity or trauma.

See also

• Respiratory system
• Thoracic diaphragm
• Intercostal nerve
• Intercostal artery
• Intercostal vein

References

Intercostal muscles Resources
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