Upper arm pain is a common complaint. This discomfort, which can range from a dull ache to a sharp sensation, is not always a simple matter of a recent injury. The upper arm, or brachium, is a complex region containing large muscles, major nerves, and tendons that connect to the highly mobile shoulder and elbow joints. Because of this intricate anatomy, the source of pain can be highly varied, sometimes even originating far from the arm itself. Understanding the distinct categories of causes is the first step toward finding relief.
Pain from Direct Muscle and Tendon Strain
The most immediate cause of upper arm pain often involves the primary muscle groups, the biceps and triceps, or their associated tendons. A muscle strain occurs when the fibers are suddenly overstretched or torn, frequently happening during heavy resistance training or forceful movement. This acute injury typically results in localized pain that worsens when the specific muscle is contracted or stretched. Severe tears can sometimes cause a visible lump, known as a “Popeye” sign, especially with a ruptured biceps tendon.
Chronic overuse injuries, such as tendinitis, are also common culprits, affecting the cords that anchor muscle to bone. Biceps tendinitis involves inflammation of the long head of the biceps tendon, which connects the muscle to the shoulder socket. The pain is generally felt in the front of the shoulder and can spread down the upper arm, often being tender to the touch. This discomfort is aggravated by repetitive overhead motions, such as those performed in swimming or tennis.
Another frequent cause is delayed onset muscle soreness (DOMS), which results from microscopic muscle damage after strenuous exercise. This type of pain is diffuse across the muscle belly, typically peaks 24 to 72 hours after the activity, and is characterized by a deep, aching feeling. This soreness is a normal physiological response to muscle repair and is self-limiting.
Pain Originating from Joint and Bursa Issues
Pain that originates in the shoulder joint but radiates into the upper arm often signals an inflammatory or structural problem. Bursitis involves the inflammation of a bursa, a small, fluid-filled sac that acts as a cushion between bones and tendons. Subacromial bursitis is frequent, occurring when the bursa beneath the acromion bone becomes irritated, often due to overuse or impingement. This typically causes pain in the outer shoulder and upper third of the arm, which is exacerbated by raising the arm, particularly in the middle range of motion.
Another source of arm pain stemming from the shoulder is adhesive capsulitis, commonly known as frozen shoulder. This condition involves the thickening and tightening of the connective tissue surrounding the joint. It develops in three stages—freezing, frozen, and thawing—and is characterized by a dull, aching pain that is often worse at night. The defining feature is a progressive loss of both active and passive range of motion, meaning the arm is stiff whether the person moves it or someone else attempts to move it. This combination of pain and profound stiffness distinguishes it from a simple muscle strain.
Pain Caused by Nerve Impingement
Upper arm pain can be a referred symptom of a compressed nerve root in the neck, known as cervical radiculopathy. The nerves that control sensation and movement in the arm exit the spine in the cervical region. Pressure from a herniated disc or degenerative changes can irritate them, causing pain that radiates down the arm, sometimes described as sharp, shooting, or burning.
The location of the pain and other symptoms depends on which nerve root is affected. For example, compression of the C5 or C6 nerve roots commonly causes pain and weakness that travels into the shoulder and the lateral (outer) part of the upper arm. This neurological pain is frequently accompanied by paresthesia, which is a tingling or “pins and needles” sensation, and numbness. A subtle sign that the issue is neurological is that lifting the arm above the head may provide temporary relief from the pain.
When Upper Arm Pain is Referred
In some instances, upper arm pain is a form of referred pain, meaning the underlying problem is not in the arm or shoulder itself, but in a distant organ. The most serious example is cardiac pain, such as that caused by angina or a heart attack. This occurs because the nerves supplying the heart share spinal cord pathways with the nerves from the arm, causing the brain to misinterpret the source of the distress. The pain is typically felt as a dull ache, heaviness, or pressure, often radiating down the left arm, although it can occur in the right arm or both.
This type of referred pain is rarely isolated and is usually accompanied by other systemic symptoms that demand immediate attention. These warning signs include chest discomfort described as pressure or squeezing, unexplained shortness of breath, nausea, sweating, or pain in the jaw or back. If sudden, severe, unexplained arm pain occurs alongside any of these symptoms, it is a medical emergency that requires prompt evaluation to rule out a life-threatening cardiac event.