GENERAL INFORMATION
The transversus thoracis is a thin, flat muscle located in the chest region. It is considered a deep muscle of the anterior thoracic wall. The muscle fibres run horizontally across the thoracic cage, playing a crucial role in the mechanical aspect of breathing.
ORIGIN
The transversus thoracis originates from the posterior surface of the xiphoid process (the small, cartilaginous extension at the lower end of the sternum) and the lower sternum (costal cartilages of the lower three to six ribs). Therefore, its origin points are well-positioned to support its function in chest wall compression.
INSERTION POINT
The muscle inserts into the internal surface of the costal cartilages of the second to the sixth ribs. Thus, its insertion points are essential for facilitating the muscle’s role in forced expiration.
MAJOR ARTERIES
The transversus thoracis receives its blood supply primarily from the internal thoracic artery, a branch of the subclavian artery. This artery ensures that the muscle gets adequate blood flow to perform its functions effectively.
NEURAL INNERVATION
The muscle is innervated by the intercostal nerves, specifically the anterior rami of the upper five or six intercostal nerves. Therefore, proper nerve function is crucial for the activation and control of the transversus thoracis muscle.
TRIGGER POINT
The transversus thoracis muscle does not typically have a recognised trigger point associated with it, so trigger point therapy is not commonly needed for this muscle.
CONCENTRIC FUNCTION
Contraction of the transversus thoracis muscle contributes to the compression of the anterior chest wall, assisting in the forced expiration of air during breathing. Thus, it is essential for adequate exhalation, particularly during strenuous activities.
ECCENTRIC FUNCTION
The transversus thoracis muscle does not have a significant eccentric function. Its primary role is during forced expiration. Consequently, its main contribution is during the exhalation phase of breathing.
ISOMETRIC FUNCTION
The muscle can stabilise the ribs and sternum during specific movements and activities, providing stability to the anterior chest wall. Therefore, it offers essential support during various physical activities.
RELATED MUSCLES (SCIENTIFIC NAMES)
- Internal Intercostal Muscles: These muscles assist in forced expiration by depressing the ribs, working synergistically with the transversus thoracis to reduce the volume of the thoracic cavity.
- Diaphragm: The primary muscle of respiration aids in the expansion and contraction of the thoracic cavity. It plays a key role in both inhalation and forced exhalation.
- Pectoralis Major: A large muscle in the upper chest aids in the movement and stabilisation of the shoulder. It also assists in deep inhalation by expanding the rib cage.
- Serratus Anterior: A muscle that helps move the scapula and plays a role in breathing by stabilising the rib cage, ensuring efficient respiratory mechanics.
ANTAGONIST MUSCLES
- External Intercostal Muscles: These muscles elevate the ribs during inspiration, opposing the action of the transversus thoracis. They are essential for expanding the thoracic cavity during inhalation.
- Diaphragm: Acts antagonistically during forced expiration by creating negative pressure in the thoracic cavity during inspiration. It is crucial for increasing thoracic volume during inhalation.
COMMON INJURIES
- Overuse Injuries: Rare but can occur with repetitive strain, leading to discomfort in the chest area. This may result from activities that heavily tax respiratory muscles, such as chronic coughing.
- Direct Trauma: It can cause bruising or strains, often resulting from impacts to the chest. Such injuries may cause pain and limit the range of motion.
- Strains: Sudden movements or heavy lifting can sometimes lead to muscle strains, though this is uncommon for the transversus thoracis. These strains can cause localised pain and tenderness.
EXERCISES
- Chest Presses: Strengthen the chest muscles and indirectly engage the transversus thoracis by applying pressure to the anterior thoracic wall. This exercise helps build overall chest strength.
- Push-Ups: Engage multiple chest and shoulder muscles, providing indirect activation of the transversus thoracis. They are excellent for developing upper body strength and endurance.
- Dumbbell Flies: Target the pectoral muscles and contribute to overall chest strength, indirectly working the transversus thoracis. This exercise promotes muscle flexibility and control.
- Cable Crossovers: Focus on chest muscle development and provide indirect engagement of the transversus thoracis. This exercise enhances muscle definition and strength.
- Chest Dips: Strengthen the lower part of the chest, indirectly activating the transversus thoracis. They are effective for improving muscle stability and endurance.
STRETCHES
- Doorway Stretch: Stretches the chest muscles, indirectly benefiting the transversus thoracis. This stretch helps open up the chest and improve posture.
- Chest Stretch Against a Wall: Increases flexibility in the chest area, indirectly stretching the transversus thoracis. This is useful for relieving muscle tension and improving range of motion.
- Horizontal Arm Stretch: It helps maintain flexibility in the chest and shoulder muscles, indirectly affecting the transversus thoracis. This stretch can help prevent muscle stiffness.
- Pectoral Stretch on a Stability Ball: It enhances chest flexibility and indirectly stretches the transversus thoracis. This stretch promotes relaxation and reduces muscle tightness.
- Arm Circles: Increase flexibility and reduce tension in the chest and shoulder muscles, indirectly benefiting the transversus thoracis. This exercise helps improve muscle coordination and range of motion.