Intercostal muscles

Definition

Intercostal muscles are a group of muscles located between the ribs that play a crucial role in the mechanics of breathing. These muscles contract and relax to facilitate the expansion and contraction of the thoracic cavity during inhalation and exhalation, thus allowing for effective airflow into and out of the lungs. Their coordinated activity is essential for both quiet breathing and more forceful respiratory actions, such as during exercise or heavy exertion.

5 Must Know Facts For Your Next Test

1. There are two main types of intercostal muscles: external intercostals, which assist with inhalation by elevating the ribs, and internal intercostals, which aid in forced exhalation by depressing the ribs.
2. Intercostal muscles are innervated by the intercostal nerves, which arise from the thoracic spinal cord and provide motor control and sensory feedback.
3. During normal breathing, external intercostal muscles are primarily active, while internal intercostal muscles become more involved during vigorous activities like exercise or coughing.
4. In cases of respiratory distress, accessory muscles such as the sternocleidomastoid and scalene muscles may also assist in breathing by helping to expand the thoracic cavity further.
5. The strength and endurance of intercostal muscles can be enhanced through regular physical activity, contributing to improved respiratory efficiency and overall lung health.

Review Questions

• How do intercostal muscles contribute to the process of inhalation?
  • Intercostal muscles play a vital role in inhalation by contracting to elevate the ribs, which expands the thoracic cavity. This expansion decreases pressure within the lungs, allowing air to flow in. The external intercostal muscles are primarily responsible for this action during normal breathing, while their coordinated movement with the diaphragm enhances the overall effectiveness of inhalation.
• Discuss how intercostal muscles function during exercise compared to resting conditions.
  • During exercise, intercostal muscles work harder than they do at rest. While resting mainly involves the external intercostals for normal inhalation, vigorous physical activity requires both external and internal intercostals. The internal intercostals help with forced exhalation by depressing the ribs and expelling air more efficiently. This coordinated effort increases overall lung ventilation, meeting heightened oxygen demands during exercise.
• Evaluate the importance of intercostal muscle strength in individuals with respiratory conditions such as asthma.
  • Intercostal muscle strength is critical for individuals with respiratory conditions like asthma because it affects their ability to breathe efficiently. Strong intercostal muscles enable better rib cage movement, enhancing airflow during both inhalation and exhalation. In asthmatic patients, improved strength can facilitate better control over breathing during an attack, allowing for more effective management of symptoms and reducing reliance on medications. This underscores the need for targeted respiratory muscle training in rehabilitation programs for those with chronic respiratory issues.

Related terms

Diaphragm: A dome-shaped muscle located beneath the lungs that contracts during inhalation to increase thoracic volume and draw air into the lungs.

Thoracic cavity: The chamber of the body that houses the lungs and heart, bounded by the rib cage and diaphragm, playing a key role in respiratory mechanics.

Pleura:

A double-layered membrane surrounding each lung, providing lubrication and facilitating smooth movement during breathing.