Pain traveling from the shoulder down the arm and sometimes into the fingers suggests an underlying issue involving the body’s major nerve pathways. This radiating pain is often neurological, following the distribution of the brachial plexus, a network of nerves originating in the neck that controls sensation and movement in the shoulder, arm, and hand. The source of the pain may be the spinal column, a tight passage near the collarbone, or the shoulder joint structure itself.
Nerve Root Compression in the Neck
The most frequent cause of true radiating pain from the shoulder to the hand is cervical radiculopathy, which is the irritation or compression of a nerve root where it exits the spine in the neck. The cervical vertebrae have openings called foramina through which the nerve roots travel. Narrowing of this space leads to compression, commonly caused by degenerative changes like bone spurs (osteophytes) or a bulging or herniated disc pushing against the nerve.
The pain is often described as sharp, burning, or electrical, following a specific path (dermatome) down the arm and into the fingers. For example, C7 nerve root compression often results in numbness or tingling in the middle finger and potential weakness in the triceps muscle. Certain neck movements, such as extending the neck or turning the head, frequently increase the intensity of the pain.
A pinched nerve root can also cause motor symptoms, including muscle weakness in the shoulder, arm, or hand, and loss of grip strength. If the pain is relieved by placing the hand over the head—a maneuver that decreases tension on the nerve root—it strongly indicates the problem originates in the cervical spine.
Thoracic Outlet Syndrome
Thoracic Outlet Syndrome (TOS) is a distinct cause of arm and hand pain involving the compression of neurovascular structures as they pass through the thoracic outlet. This narrow space is bordered by the collarbone, the first rib, and the scalene muscles. TOS includes compression of the brachial plexus nerves or the subclavian artery and vein. Neurogenic TOS is the most common form, accounting for about 95% of cases, and involves compression of the brachial plexus.
Neurogenic TOS results in symptoms similar to cervical radiculopathy, including pain, numbness, and tingling throughout the arm and hand, often accompanied by arm fatigue and a weakened grip. Symptoms are exacerbated by activities requiring the arm to be held in an elevated or overhead position, such as throwing a ball or styling hair. The compression site is typically lower than the neck, which helps distinguish it from cervical radiculopathy.
The less common forms, venous and arterial TOS, are categorized as vascular TOS and involve blood vessel compression. Venous TOS can cause arm swelling and discoloration due to vein compression. Arterial TOS, the rarest type, involves artery compression and may present with coldness, color changes in the fingers, or a weak pulse.
Referred Pain from Shoulder Joint Issues
Pain extending down the arm can originate from the shoulder joint itself, a phenomenon known as referred pain. This occurs because the same nerve pathways supply both the shoulder joint structures and the skin and muscles further down the arm. The brain interprets the pain signals as coming from the arm, even though the irritation is localized to the shoulder.
Conditions like rotator cuff tendinitis, bursitis, or adhesive capsulitis (frozen shoulder) are common causes of this referred discomfort. The pain is typically a dull ache extending down the upper arm, sometimes reaching the elbow. It rarely causes the sharp numbness and tingling that reaches the fingers, unlike true nerve compression. This pain is defined by being directly provoked by movement of the shoulder joint.
Unlike nerve root pain, which is often aggravated by neck movement, referred pain from the shoulder worsens when the shoulder is actively used or moved in specific directions. For instance, reaching overhead or behind the back will increase the pain. A diagnostic test often involves injecting a local anesthetic into the shoulder joint; if the arm pain temporarily disappears, the joint is confirmed as the origin of the problem.
When Pain Requires Immediate Medical Attention
While most causes of shoulder-to-hand pain are not medical emergencies, certain accompanying symptoms are red flags requiring immediate medical evaluation. The sudden onset of severe weakness, paralysis, or the inability to move the arm, especially following a traumatic injury, suggests a potentially severe nerve or structural issue, such as a fracture.
Pain accompanied by signs of acute vascular compromise requires emergency care. These signs include the sudden loss of pulse in the arm, a dramatic change in the hand’s color, or rapid, unexplained swelling, which can indicate an acute vascular occlusion. A medical emergency is also suggested if the pain is accompanied by chest pressure, shortness of breath, or profuse sweating, which may signal a cardiac event.
Any new or sudden loss of bowel or bladder control, alongside arm or neck symptoms, is a sign of potential spinal cord compression and demands immediate attention. These neurological symptoms indicate a serious, rapidly progressing condition requiring urgent intervention.