The wall of the chest cavity is made up of many muscles which attach to the bones or ligaments of the chest. These muscles are not only responsible for movement of structures within the thorax (chest cavity) and may also play a part in head, neck, upper limb and abdominal movement. Any muscle chest pain that is aggravated by certain movements will assist your doctor in identifying which of these muscles may be injured. Ligaments and tendons may also be responsible for the pain.
The diaphragm is the flat muscle that lies at the bottom of the thoracic cavity. It separates the contents of the chest from that of the abdomen and is a major muscle of respiration. At times, muscle chest pain may only be noticed upon movement or breathing or persist even upon rest.
Muscles at the Front of the Chest
There are large and small chest muscles some of which lie superficially and others are located deeper. If you are experiencing muscular chest pain that seems more localized to a specific area, then it is important to know which of the muscles in this area may be responsible.
- The pectoralis muscles include the pectoralis major and pectoralis minor. These muscles are often referred to as the ‘pecs’ and lie under the breast. The pectoralis major is a large muscle that lies more superficially while the pectoralis minor muscle lies underneath it, more towards the sides of the chest. Pain from these muscles are sometimes mistaken for breast pains.
- The serratus anterior muscle is located on the side and slightly to the front of the chest cavity.
- The intercostal muscles are located between the ribs.
- The rectus abdominis muscle is an abdominal muscle that is known as the ‘six pack abs’ when it is well developed. The upper part of this muscle lies on the bottom middle part of the chest wall.
- The external abdominal oblique muscle or ‘side abs’ lies on the lower part of the chest cavity crossing to the sides. There are also the internal abdominal oblique muscles which lie underneath the external oblique muscles.
Other large and small muscles lying on the chest wall may also be involved but may be difficult to isolate without medical investigation.
- If the muscular chest pain increases when moving the upper limb (arm), then this is more likely due to the pectoralis major or serratus anterior muscles.
- If the chest pain increases when sitting up from a supine (lying flat) position, when rotating the chest or while walking, then it may be due to the rectus abdominis or abdominal oblique muscles.
- If the chest pain increases when breathing this can involve many muscles including the diaphragm, intercostal, pectoralis minor, rectus abdominis and abdominal oblique muscles.
Muscles at the Back of the Chest (Torso)
There are also large and small muscles which make up the back of the chest cavity.
- The trapezius muscle is a diamond shaped back muscle extending from the base of the skull to the mid back. The ‘traps’ also fans out to the sides of the body where it connects to the back of the shoulders.
- The rhomboid muscles lie under the the trapezius muscle. There are two rhomboid muscles on each side – the rhomboid major and rhomboid minor. These muscles extend from the vertebrae to the medial (inner) border of the scapula.
- The teres muscles are made up of the teres major and teres minor muscles. They extend from the lower part of the lateral (outer) part of the scapula to the long bone of the upper limb (humerus).
- The latissimus dorsi muscle extends from the mid to lower back to connect to the inside of the upper limb. It makes up the lower part of the back of the chest cavity.
- The infraspinatus muscle lies below the the spine of the scapula while the supraspinatus muscle lies above the spine of the scapula.
There are other large and small muscles at the back of the chest cavity that are involved in motion of the trunk, upper limb, head and neck but it may be difficult to isolate without proper medical investigation.
- If the pain at the back of the chest occurs when moving the neck or shoulders, then the trapezius, rhomboid, infra- or supraspinatus muscles may be involved.
- If the pain at occurs when moving the upper limb (arm), then the latissimus dorsi, teres major or minor muscle may be involved.
- If the pain at the back of the chest occurs when breathing, then the trapezius, rhomboids , diaphragm or intercostal muscles may be involved.
It is important to note that while some muscles may not play an important role in motion of adjacent body parts or for respiration (breathing), they may still be used as accessory muscles for these functions under certain conditions. The muscles listed above are not the only muscles in this area but are the easiest to identify based on their location and function(s).
Causes of Muscle Chest Pain
One or more of the following causes could account for muscle chest pain. Only consider chest pain to be muscular if your have excluded the causes of lung chest pain and heart chest pain. Even in cases of exertion, it could be your respiratory or cardiovascular organs that may be the site of injury, inflammation or infection with the chest pain only becoming pronounced upon physical activity.
- Trauma ranging from dull aches in cases if blunt force injuries to severe stabbing pain when the muscle is pierced. Muscle pain after surgery is another possible caue.
- Muscle strain. In terms of muscle strain, balls of spasm or ‘trigger points’ may be felt at certain points along the course of the muscle and pressure at these spots may cause a sharp or burning pain. Otherwise a dull ache felt along the entire muscle may be experienced.
- Muscle cramps due to overuse, dehydration, hormonal disorders or chronic conditions like diabetes, rheumatoid arthritis, hyper- or hypothyroidism.
- Torn muscle.
- Fibromyalgia. The pain is usually chronic, intermittent or constant, and occurs at multiple sites simultaneously.
- Benign or malignant tumors.
- Infections either localized or generalized.