Pain in the upper arm, specifically the region of the humerus between the shoulder and the elbow, is a common complaint. This area is a complex junction of large muscles, tendons, nerves, and vascular structures, meaning discomfort can arise from various sources. Since this segment is involved in nearly all pushing, pulling, lifting, and rotation movements, the cause of pain is frequently tied to mechanical stress or daily activity. Understanding the specific nature and location of the pain helps determine if it stems from soft tissue, nerve pathways, or bone structure.
Pain Originating from Muscle and Tendon Strain
The most frequent origin of upper arm pain is the soft tissue, involving the large muscles and their connecting tendons. Tendons are thick, cord-like structures that link muscle to bone. Pain in the front of the humerus is often linked to the biceps muscle and its tendon, while pain in the back relates to the triceps.
Biceps tendinopathy is an irritation and inflammation of the long head of the biceps tendon near the shoulder. This condition develops gradually from repetitive overhead motions or wear-and-tear, causing pain that can radiate down the front of the upper arm. The discomfort is typically felt deep in the shoulder area and may worsen when lifting or pulling objects.
The triceps muscle, which runs along the back of the arm, can also be affected by tendinopathy or acute muscle strain. Triceps tendinopathy causes pain near the elbow attachment but can track upward along the humerus. This injury often occurs with forceful extension of the arm, such as during weightlifting exercises.
An acute muscle strain, or a “pulled muscle,” involves a sudden overstretch or tear of the muscle fibers, distinct from chronic tendinopathy. These strains result from a single, forceful event, causing immediate localized pain, swelling, and sometimes bruising deep within the muscle belly. The severity of the pain and loss of function depend on the grade of the muscle fiber tear.
Causes Related to Nerve Compression and Irritation
Pain between the elbow and shoulder can sometimes be a manifestation of nerve irritation, where the discomfort originates outside the arm itself but is felt along the nerve’s pathway. This is known as referred pain, and it often presents with neurological symptoms like numbness or tingling. The most common source of referred arm pain is the neck, involving cervical radiculopathy.
Cervical radiculopathy occurs when a nerve root in the cervical spine becomes compressed or irritated by a herniated disc or bone spur. Since the nerves that supply the entire arm exit the spinal cord in the neck, this compression can send pain, weakness, or a pins-and-needles sensation down the arm. The specific location and quality of the pain often follow a predictable pattern corresponding to the affected nerve root.
The radial nerve, which travels down the back of the arm, is vulnerable to entrapment as it spirals around the middle of the humerus bone. This nerve supplies sensation to part of the hand and controls the muscles that allow the wrist and fingers to extend. Compression in this area can lead to radial nerve entrapment.
Entrapment of the radial nerve typically causes pain along the back and side of the upper arm, sometimes accompanied by weakness in extending the wrist, a symptom referred to as “wrist drop.” The nerve can be compressed following a fracture of the humeral shaft. This type of nerve-related pain is often described as burning or electric in quality and is distinct from the dull ache of a muscle strain.
Structural and Non-Mechanical Contributors
Less common but more serious causes of upper arm pain involve the humerus bone itself or systemic issues. Pain that is deep, constant, and unrelated to movement should raise suspicion of a structural or non-mechanical problem.
A fracture of the humerus shaft, the long central portion of the bone, is a significant cause of acute pain in this area. These breaks usually result from substantial trauma, such as a fall or a motor vehicle accident, causing immediate, severe pain and an inability to move the arm. A stress fracture is a less dramatic cause, developing gradually from repetitive, low-impact stress that exceeds the bone’s capacity to repair itself.
Systemic diseases can also manifest as upper arm pain. For instance, osteomyelitis, a bone infection, can cause intense, localized pain accompanied by fever and chills. In rare instances, pain radiating down the left arm can be a symptom of a heart attack or angina (reduced blood flow to the heart muscle). This pain is typically accompanied by chest discomfort, shortness of breath, or sweating.
Recognizing Serious Symptoms and Seeking Medical Help
Most upper arm pain is due to minor soft tissue injuries that respond well to rest and anti-inflammatory medication. However, certain symptoms require immediate medical evaluation to prevent complications from serious injuries or underlying conditions.
Pain accompanied by a visible deformity, such as an unnatural bend, suggests a possible fracture and necessitates emergency care. Any inability to move the arm or a sudden, complete loss of strength, particularly if associated with numbness or tingling, should be assessed quickly to rule out severe nerve damage or a complete tendon tear.
If the pain is linked to systemic symptoms like fever, unexplained chills, or significant weight loss, a physician should be consulted promptly to investigate for infection or other medical issues. Pain that radiates into the chest, jaw, or down the left arm, especially when accompanied by profuse sweating or shortness of breath, requires emergency medical attention due to the possibility of a cardiac event. For persistent pain that does not improve after several days of rest and ice, a consultation with a healthcare provider can help accurately diagnose the cause and initiate appropriate treatment.