Pain in the shoulder and upper back area is often traced back to the Teres Major muscle. This muscle plays a significant part in arm movement, and its discomfort frequently results from overuse or an acute strain. Understanding the location and function of the Teres Major is the first step toward finding relief, as the symptoms can sometimes mimic those of more widely known shoulder issues. This guide will explore the anatomy of this muscle, the primary reasons it becomes painful, and the immediate steps you can take to manage the discomfort.
Understanding the Teres Major Muscle
The Teres Major is a thick, flattened muscle situated on the posterior side of the torso. It originates from the inferior angle of the scapula (the lower tip of the shoulder blade) and inserts on the front of the humerus (the upper arm bone). This positioning allows it to act on the shoulder joint to produce three main actions: extension, adduction, and internal rotation of the arm. Extension moves the arm backward, adduction pulls the arm toward the midline, and internal rotation turns the arm inward. The muscle works closely with the larger latissimus dorsi due to their similar actions. The Teres Major is not one of the four muscles that make up the rotator cuff.
Primary Causes of Teres Major Pain
Pain in the Teres Major muscle is most frequently caused by acute strain or chronic overuse that overwhelms the muscle fibers. An acute strain occurs when the muscle is suddenly forced to exert excessive power or stretch, such as during a forceful throw in baseball or a sudden, heavy lift. This exertion can lead to micro-tears within the muscle, resulting in sharp pain and immediate discomfort in the back of the shoulder or armpit area. Chronic overuse injuries are common in individuals who participate in activities requiring repetitive arm movements, like swimming, tennis, or certain weightlifting exercises, particularly pull-ups or rows. These repeated actions cause microtrauma over time, leading to inflammation and a deep, aching pain that may worsen with activity.
The muscle is also susceptible to developing myofascial pain syndrome, characterized by localized trigger points that can refer pain to other areas of the shoulder. Poor posture significantly contributes to Teres Major pain by placing the muscle in a mechanically disadvantageous position for prolonged periods. When the shoulders are rounded forward, the Teres Major is held in a shortened, stressed state, which increases tension and leads to stiffness and discomfort. This chronic tension can create muscular imbalances that make the muscle more vulnerable to strain. Direct trauma, such as a fall onto the side of the shoulder blade, can also cause impact or stretch injuries to the muscle.
Immediate At-Home Relief Strategies
For immediate self-care of Teres Major pain, the R.I.C.E. principles are the starting point for managing acute symptoms. Rest is necessary, meaning avoiding activities that reproduce the pain, such as overhead reaching or heavy lifting. Applying ice to the painful area for 15 to 20 minutes several times a day during the first 48 hours helps reduce local swelling and inflammation. Once the initial acute pain phase subsides, gentle stretching can help prevent muscle tightness and restore mobility.
Stretching Techniques
A simple cross-body stretch targets the Teres Major by bringing the affected arm across the chest and gently supporting the elbow with the opposite hand. The doorway stretch can be modified to target the posterior shoulder by facing the doorway and placing the arm on the frame at shoulder height.
Over-the-counter nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen or naproxen, help manage pain and reduce inflammation. After the first few days of icing, moist heat can be applied to the area to increase blood flow and relax the muscle tissue. Self-massage techniques, using a lacrosse ball or similar tool against a wall to target tender spots near the lower shoulder blade, can also help release trigger points.
When to Seek Professional Treatment
While many Teres Major strains respond well to at-home care, specific signs indicate the need for a professional medical evaluation. If the pain persists or worsens after seven to ten days of consistent rest and self-care, a consultation is warranted to ensure a proper diagnosis. Pain that is severe, limits your daily activities, or prevents you from getting a restful night’s sleep should also prompt an office visit.
Any sign of neurological involvement, such as numbness, tingling, or radiating pain extending down the arm, requires prompt attention from a healthcare provider. A sudden inability to move the arm, significant weakness, or if the pain resulted from a traumatic event like a fall necessitates immediate medical assessment. Professionals can use imaging techniques like MRI or ultrasound to distinguish between a minor strain and a more serious tear. Once a diagnosis is confirmed, professional treatment often involves physical therapy. Therapy focuses on targeted strengthening exercises for the surrounding shoulder and back muscles to improve joint stability, correct muscle imbalances, and gradually restore the full range of motion without pain. Early intervention and adherence to a physical therapy plan are important for preventing chronic issues and achieving a full recovery.