Pain localized to the upper left back, particularly beneath the shoulder blade (the subscapular region), is a common complaint. This area is a convergence point for pain signals originating from muscular structures, the spinal column, and internal organs. The nature of the pain—such as a dull ache, sharp burning, or deep pressure—often hints at the underlying cause. While most cases stem from mechanical issues, pain referred from non-musculoskeletal sources requires urgent assessment. Understanding these varied origins is key to appropriate treatment.
Muscular and Postural Sources
Most discomfort in the upper back relates directly to muscle strain and posture during daily activities. Prolonged sitting with poor posture, such as a rounded back or hunched shoulders, places sustained strain on the muscles stabilizing the shoulder blades. This chronic overuse leads to muscle fatigue, tension, and the formation of localized, irritable trigger points.
The rhomboid muscles, which connect the shoulder blades to the spine, are frequently implicated. When constantly stretched by forward-slumped posture, they develop trigger points that feel like a persistent, deep “knot” under the shoulder blade. The middle trapezius muscle, which helps retract the shoulders, can also become strained due to overuse or stress-related tension.
This musculoskeletal pain is often described as a dull, aching sensation that worsens with movement or after long hours at a desk. The pain may be temporarily relieved by massage or stretching. Continuous muscle pulling contributes to inflammation and spasm, causing palpable tightness near the spine or the medial border of the scapula.
Spinal and Nerve Compression
If pain under the shoulder blade is sharp, burning, or accompanied by tingling, the source may involve the spine and nerve pathways. The nerves supplying sensation to the upper back originate high in the cervical spine (neck). Specifically, nerve roots from the C5, C6, and C7 levels travel down into the shoulder and upper back area.
Cervical radiculopathy occurs when one of these nerve roots is compressed or irritated, often due to a herniated disc or degenerative changes like bone spurs. Although originating in the neck, the pain is frequently perceived as referred pain near the shoulder blade. This happens because the brain misinterprets the signal along the shared nerve pathway.
Structural issues within the thoracic spine, where the shoulder blades are located, can also cause subscapular pain. Facet joint dysfunction or a thoracic disc issue can irritate local nerves. These causes often result in pain localized to the spine itself and may worsen with twisting or backward bending movements.
Referred Pain from Visceral Organs
While mechanical causes are the most common, pain in the upper left back can sometimes manifest from a serious, non-musculoskeletal problem originating in the chest or abdomen. This is known as visceral referred pain, where shared nervous system pathways cause internal organ discomfort to be felt in a distant location. Since the heart and lungs share nerve segments with the upper back, pain from these organs can be felt in the left subscapular area.
Cardiac Causes
Angina or an acute heart attack can present as pressure, aching, or a squeezing sensation in the left shoulder blade or across the upper back. This is a particularly important consideration on the left side, and the pain typically does not change with movement or position, distinguishing it from a muscle strain.
Pulmonary and Gastrointestinal Causes
Pulmonary issues can also refer pain to this area. Conditions like pleurisy, which is inflammation of the lining around the lungs, may cause sharp, localized pain that worsens with deep breaths, coughing, or sneezing. Furthermore, certain gastrointestinal problems, such as esophageal spasms or ulcers in the upper part of the stomach, can project pain into the mid-back region. The convergence of sensory nerves from these internal structures on the same spinal cord segments as the upper back muscles creates this mislocalized pain signal.
When to Seek Medical Attention
Understanding when upper back pain requires immediate medical evaluation is critical due to the potential for serious underlying causes. Any pain under the left shoulder blade accompanied by “red flag” symptoms warrants an emergency room visit. These alarming signs include:
- Sudden chest pressure
- Shortness of breath
- Dizziness
- Cold sweats
- Pain that radiates into the jaw or left arm
Medical attention should also be sought if the pain does not change with movement, rest, or position, suggesting a non-musculoskeletal origin. A consultation is advisable for persistent pain lasting longer than a few weeks, even without acute symptoms. Other concerning signs requiring follow-up include unexplained weight loss, fever, or new weakness, numbness, or tingling extending into the arm or hand.