From the Research
The transversus thoracis muscle primarily functions as an accessory muscle of expiration during respiration, assisting in forced expiration by pulling the ribs downward and inward. The function of the transversus thoracis muscle in respiration is to decrease the volume of the thoracic cavity, which helps expel air from the lungs. This small, thin muscle is located on the inner surface of the anterior thoracic wall, originating from the lower sternum and xiphoid process and inserting onto the costal cartilages of ribs 2-6. While not a primary respiratory muscle like the diaphragm or intercostals, the transversus thoracis becomes more active during labored breathing, such as during exercise or in respiratory conditions that require increased expiratory effort. Its contraction helps counteract the natural elastic recoil of the lungs and chest wall, providing additional force for expiration when needed. The muscle's anatomical position allows it to effectively decrease the anteroposterior diameter of the thorax during contraction, contributing to the mechanical process of expiration. However, the provided evidence does not directly discuss the transversus thoracis muscle, but rather the transversus abdominis muscle 1. Despite this, the general understanding of accessory muscles of expiration can be applied, and it is known that muscles such as the transversus thoracis play a role in forced expiration. In contrast, the study on clinical applications of lung function tests 2 does not provide information on the specific function of the transversus thoracis muscle. Therefore, based on general knowledge and the available evidence, the transversus thoracis muscle is considered an accessory muscle of expiration, but its specific function and activation patterns may vary depending on the respiratory condition. Key points to consider include:
- The transversus thoracis muscle assists in forced expiration
- It is located on the inner surface of the anterior thoracic wall
- It becomes more active during labored breathing
- Its contraction helps counteract the natural elastic recoil of the lungs and chest wall However, more specific information on the transversus thoracis muscle is needed to fully understand its function in respiration.