Pain in the top left back prompts concern due to the complex anatomy of the area, which includes the thoracic spine, surrounding soft tissues, and proximity to vital internal organs. This specific location, between the shoulder blade and the spine, is a common site for mechanically induced discomfort. However, it can also register pain originating from elsewhere. Understanding the distinction between muscular, structural, and referred pain is the first step toward determining the cause.
Common Musculoskeletal Causes
Discomfort in the upper back usually stems from the surrounding muscles and ligaments due to mechanical stress. The rhomboid muscles, located between the shoulder blade and the spine, are frequent sources of pain. These muscles stabilize the shoulder blade and are easily strained by repetitive motions or acute injuries, leading to a deep, aching sensation that worsens with movement or deep breathing.
Poor posture, such as rounded shoulders during prolonged desk work, places chronic strain on the upper back muscles. This habitual slouching causes muscle fatigue and can lead to the development of myofascial trigger points. These palpable, tight knots are tender to the touch and can cause localized pain or refer discomfort to nearby areas.
Acute muscle spasms can also occur from sudden, unaccustomed physical activity, such as lifting a heavy object incorrectly, or from a strenuous bout of exercise. When a muscle is overused or injured, it responds by tightening up as a protective mechanism, causing sharp pain and limited range of motion. Unlike spinal pain, which may have neurological symptoms, this soft tissue pain is generally localized and changes in intensity with specific movements.
Spinal Structure and Nerve Involvement
Pain originating directly from the thoracic spine, the segment of the backbone that runs through the upper back, is less common than muscular pain. The thoracic spine is relatively stable due to its connection with the rib cage. Nevertheless, the small joints connecting the vertebrae, known as facet joints, can become irritated or stiff.
Thoracic facet joint irritation causes a localized ache or sharp pain, often felt slightly to one side of the spine, aggravated by twisting, bending, or deep breathing. Inflammation in these joints can lead to a “locked” feeling or a sharp, catching pain with sudden movements. Degenerative changes, such as mild arthritis, can also affect these joints over time, causing morning stiffness and reduced flexibility.
When a nerve root in the thoracic spine becomes compressed, thoracic radiculopathy can develop. This rare condition results from a herniated or bulging disc pressing on the nerve as it exits the spinal column. Symptoms are neurological, presenting as sharp, burning, or stabbing pain that follows the nerve path around the rib cage. This nerve pain may lead to numbness or a “pins and needles” sensation, sometimes radiating to the chest or abdomen.
Serious Causes and Referred Organ Pain
Pain in the top left back that does not change with movement or rest, or is accompanied by systemic symptoms, may be a sign of referred pain originating from an internal organ. Referred pain occurs because the nerves supplying internal organs share pathways with nerves supplying the back. The brain misinterprets the visceral pain signal as coming from the back location.
Given the left-side location, pain can be referred from the heart, which is a serious consideration. A heart attack, especially in women, can present with pain felt in the upper back, jaw, or arm, sometimes without classic chest pressure. Similarly, an aortic dissection (a tear in the wall of the aorta) can cause sudden, severe, tearing pain that radiates to the back and is a life-threatening emergency.
Pulmonary conditions can also refer pain to the top left back, especially if they involve the lining of the lung or the diaphragm. Pleurisy, an inflammation of the lung membrane, causes sharp chest pain that intensifies with deep breaths, coughing, or sneezing, and this discomfort can be felt in the upper back. In rare instances, a pulmonary embolism (a blockage in a lung artery) can cause sudden back pain accompanied by shortness of breath and chest discomfort.
When to Seek Immediate Medical Attention
Certain warning signs, known as “red flags,” indicate that back pain requires immediate medical evaluation. Seek emergency medical attention if the pain is sudden, crushing, or the most severe you have ever experienced. This includes pain that is unrelenting and not relieved by rest or positional changes.
Immediate care is necessary if the back pain is accompanied by symptoms suggesting nerve compression or systemic illness. These include new numbness, tingling, or weakness in the arms or legs, or any loss of control over the bladder or bowels. A fever, chills, or unexplained weight loss are also serious indicators. Furthermore, sharp pain searing through to the chest, or pain accompanied by shortness of breath, dizziness, or chest pressure, warrants an immediate trip to the emergency room.