Identifying Intercostal Muscles | Biology for GCSE/IGCSE - Year 11 PDF Download

Identifying Intercostal Muscles

Intercostal muscles play a vital role in the mechanics of breathing, aiding in the expansion and contraction of the rib cage.

Muscles and Their Functions

• Intercostal muscles operate by pulling on bones rather than pushing them, facilitating the movement of the rib cage.
• Two sets of intercostal muscles are necessary: one set elevates the rib cage, while the other depresses it.
• External intercostal muscles are situated externally on the rib cage, assisting in lifting the rib cage during inhalation.
• Internal intercostal muscles are located internally within the rib cage, aiding in the lowering of the rib cage during exhalation.

For instance, when you inhale deeply, your external intercostal muscles contract, lifting the rib cage upwards, allowing the lungs to expand and fill with air. Conversely, during exhalation, the internal intercostal muscles contract, reducing the size of the rib cage to expel air from the lungs.

Intercostal Muscles

• External Intercostal Muscles: These muscles are positioned on the outer part of the rib cage. They play a crucial role in the process of inhalation by elevating the rib cage.
• Internal Intercostal Muscles: Situated on the inside of the rib cage, these muscles aid in the exhalation process by depressing the rib cage.

Examples:

• Example of External Intercostal Muscles: Imagine when you take a deep breath in, the action of these muscles helps expand your chest cavity, allowing more air into your lungs.
• Example of Internal Intercostal Muscles: When you forcefully exhale, such as when blowing out candles on a birthday cake, these muscles contract to reduce the space in the chest cavity, pushing the air out.