Chest Pain
The primary muscle that causes chest pain is the large muscle located on each side of the sternum called the Pectoralis Major. Knots in this muscle cause local pain in the chest as well as refer pain down the arm. Knots in this muscle cause local pain in the chest as well as refer pain down the arm. Muscle knots in this muscle can mimic a heart attack. Other small muscles with muscle knots cause pain on the side of the chest and along the sternum bone.
Causes
I Feel
Chest Pain
When the large Pectoralis Major muscle, specifically its outer (Lateral Margin) and lower (Sternal Section) portions, is causing trouble, the main complaint is often a widespread pain across the chest wall. You’ll typically feel a deep, burning ache that runs across your chest and can settle right along the front of your shoulder and down the inner side of your arm. This muscle’s job is to pull your arm across your body and down, so you’ll notice the pain gets significantly worse during activities that involve forceful pushing, like bench pressing, or swinging a golf club. It can be super tender to press on the muscle along the sternum (breastbone). Issues here can sometimes be mistaken for heart-related discomfort due to the location of the pain, leaving the whole chest feeling constricted and tight.
Heart Burn
When the large Pectoralis Major muscle, specifically its outer (Lateral Margin) and lower (Sternal Section) parts, is acting up, the referred pain is notoriously deceptive. You’ll typically feel a deep, burning ache that runs across your chest wall, often mimicking the discomfort of heartburn or even a heart issue. The pain frequently settles along the breastbone (sternum) and can shoot down the inner side of your arm. This muscle’s job is to pull your arm across your body, so you’ll notice the ache gets significantly worse during activities that involve forceful pushing or stretching the chest open. It can be super tender to press along the muscle’s attachment points. Because the pain location is so close to the chest, issues here can be very alarming, making the whole upper torso feel constricted and tight.
Breast Tenderness
When the large Pectoralis Major muscle, specifically its outer (Lateral Margin) and lower (Sternal Section) parts, is strained, the referred pain can be very specific and often mistaken for other issues. You’ll typically feel a deep, burning ache across the chest, and this discomfort can settle as tenderness or soreness in the breast tissue itself. The pain frequently runs along the breastbone (sternum) and can shoot down the inner side of your arm. This muscle’s job is to pull your arm across your body, so you’ll notice the ache gets significantly worse during activities that involve forceful pushing or stretching the chest open. It can be super tender to press on the muscle along the side of the breast. Because the pain location is so close, issues here are a common cause of mysterious, non-glandular breast discomfort.
I Feel
Chest Pain
When the small Pectoralis Minor muscle, which is tucked deep beneath your main chest muscle, is irritated, its effect on your chest wall can be quite concerning. You’ll typically feel a persistent, deep ache right in the front of your shoulder and upper chest, sometimes settling as a tight, worrisome pain that runs along your breastbone. This muscle’s function is to pull your shoulder blade forward and down. Hunching your shoulders forward—common when sitting at a desk—shortens this muscle, making it tight and prone to spasm. You’ll notice the discomfort gets worse when you try to stand up straight or pull your shoulders back. Because of its location, tension here can easily be mistaken for heart-related pain, making the entire chest feel constricted and limited.
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Pain or Discomfort Underneath the Collar Bone
When the Sternalis muscle, a small, occasionally present muscle running vertically alongside your breastbone (sternum), is strained, the pain is usually sharp and highly localized. You’ll typically feel a deep, intense ache concentrated right underneath the collarbone and along the breastbone itself. This discomfort can feel like a persistent, burning pressure right in the center of your chest. Since this muscle lies near the attachments of the chest and ribcage, you’ll notice the pain gets significantly worse during actions that involve stretching the chest open, like reaching your arm wide or taking a very deep breath. It can be super tender to press directly along the sternum. Due to its location, tension here can cause anxiety as the pain is easily mistaken for heart-related or rib issues, leaving your chest feeling stiff and highly sensitive to movement.
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Chest and Arm Pain
When the deep muscles on the side of your neck—the Scalene muscles (Anterior, Medius, and Posterior)—are strained, the pain you feel often extends to your chest. You’ll typically feel a deep, persistent ache along the side of your chest and up near the collarbone, which can sometimes feel like a sharp, worrisome tightness right in the chest wall. These muscles help with head movement and are essential for lifting your first two ribs during breathing. Shallow, stressful breathing or holding a forward head posture can easily cause them to tense up. Because the Scalenes are positioned right next to the major nerves and blood vessels traveling to the arm, tension here can also cause confusing numbness or pain in the arm, often making chest stiffness worse when you breathe deeply.
I Feel
Pain or Discomfort Underneath the Collar Bone
When the Subclavius muscle, that tiny, stabilizing muscle tucked right underneath your collarbone, is causing discomfort, the sensation is highly localized but surprisingly impactful. You’ll typically feel a deep, intense ache concentrated right underneath the collarbone, often feeling like a persistent pressure right there on the upper chest. This muscle helps anchor your collarbone, keeping it stable, so it gets overworked by repetitive overhead reaching, carrying heavy shoulder bags, or maintaining poor posture that causes your shoulder to roll forward. It can be super tender if you press firmly underneath the middle of the collarbone. Because of its location near major nerves and blood vessels, tension here can cause a feeling of heaviness or vague numbness down the arm, leaving your shoulder feeling weak and unreliable during movement.
I Feel
The Stabbing Pain in Your Side and Chest
When the Serratus Anterior muscle, located deep on the side of your ribcage under the armpit, is compromised, the pain you feel often centers on your chest and side. You’ll typically feel a persistent ache or a sharp, “stitch-like” pain in your side and chest wall, sometimes radiating under the shoulder blade. This muscle is vital for stabilizing your shoulder blade against your ribs and helping you push things, so it gets overworked from actions like excessive pushing, throwing, or holding your arm out in front of you. When the muscle is tight, it can cause tenderness in the armpit area and make your breathing feel restricted—especially when taking a deep breath. Due to its location, this tension is often a hidden source of chest wall discomfort, leaving your breathing and pushing movements feeling painful and limited.