Pain in the back of your shoulder most commonly comes from the rotator cuff, specifically the muscles and tendons that sit along the rear of your shoulder blade. But several other structures in that area can be the source, including the shoulder blade itself, a pinched nerve in your neck, or compressed nerves around the shoulder joint. The cause usually depends on whether the pain came on suddenly or built up gradually, and whether certain movements make it worse.
Rotator Cuff Problems
The rotator cuff is a group of four muscles and their tendons that wrap around the ball of your shoulder joint, holding it snugly in its socket. Two of these muscles sit on the back of your shoulder blade: the infraspinatus, which rotates your arm outward, and the smaller teres minor just below it, which assists with that same rotation. When either of these muscles or their tendons become irritated, worn down, or torn, the pain concentrates in the back of the shoulder.
Rotator cuff pain typically develops gradually over weeks or months rather than appearing overnight. You’ll notice it most when raising or lowering your arm, reaching behind your back, or lying on the affected side at night. The pain often spreads to the outside of the shoulder and upper arm. Over time, you may lose strength or range of motion in that arm. This kind of wear-and-tear damage is extremely common, especially after age 40, though younger people who do repetitive overhead activities like throwing, swimming, or painting can develop it too.
Tears can also happen suddenly from a fall on an outstretched hand or a direct collision. A sudden tear usually produces immediate sharp pain and noticeable weakness when you try to rotate your arm outward or lift it away from your body.
Bursitis and Impingement
Between the rotator cuff and the outer layer of larger shoulder muscles sits a small fluid-filled sac called a bursa. Its job is to reduce friction between these moving layers. When the rotator cuff tendons become irritated or swollen, they can squeeze this bursa, inflaming it. The result is a deep, aching pain that can settle in the back of the shoulder and flares with overhead movements. Bursitis rarely develops on its own. It usually rides alongside tendon irritation or impingement, where the tendons get pinched between the bones of the shoulder during certain arm positions.
Pinched Nerve in the Neck
Sometimes the problem isn’t in your shoulder at all. The nerves that supply your shoulders, arms, and upper back exit from your cervical spine in the neck. When one of these nerve roots gets compressed, typically by a bulging disc or a bone spur, the pain can radiate into the back of your shoulder even though the shoulder itself is perfectly healthy.
This type of pain feels distinctly different from a muscle or tendon problem. People describe it as sharp or burning rather than a dull ache. It often comes with numbness, tingling, or a “pins and needles” sensation running down the arm. Moving your neck, especially extending or straining it, tends to increase the pain. One telling clue: some people find that placing their hands on top of their head temporarily relieves the pain, because that position takes pressure off the compressed nerve root. If your posterior shoulder pain travels with any of these neurological symptoms, the neck is worth investigating.
Nerve Compression Around the Shoulder
Less commonly, a nerve can be compressed right at the shoulder itself. The suprascapular nerve runs across the back of the shoulder blade and controls two of the rotator cuff muscles. When it gets trapped, usually at a small notch in the bone, it causes deep posterior shoulder pain that feels dull, burning, or aching. Nearly 98% of people with this condition report shoulder pain as their primary symptom. The pain is one-sided and can radiate into the neck or down the arm, sometimes accompanied by weakness.
In advanced cases, you may notice visible wasting of the muscles on the back of the shoulder blade, though this only shows up in about 15 to 34% of cases. Pain often increases with cross-body movements or internal rotation of the arm. This condition is more common in overhead athletes like volleyball players and swimmers, and diagnosing it usually requires nerve conduction testing along with imaging.
A related but rarer condition involves compression of the axillary nerve in a space behind the shoulder joint. This produces similar posterior shoulder pain with numbness and weakness that can radiate down the arm. It’s easy to mistake for a rotator cuff problem, which is one reason persistent posterior shoulder pain that doesn’t improve with rest deserves a thorough evaluation.
Shoulder Blade Dysfunction
Your shoulder blade isn’t fixed in place. It glides and tilts across your upper back with every arm movement, and its positioning is critical for the shoulder joint to work properly. When the muscles that control the shoulder blade aren’t coordinating well, it can move abnormally during arm movements. This puts extra stress on the rotator cuff, the joint capsule, and the surrounding tissues, producing pain that you feel across the back of the shoulder.
This kind of dysfunction is often rooted in motor control problems rather than pure weakness. Because the shoulder blade sits on the back of your rib cage where you can’t see it, your brain has limited visual feedback for positioning it correctly. Poor posture, prolonged desk work, muscle imbalances from training, or compensation after a previous injury can all throw off shoulder blade movement patterns. The fix usually involves targeted exercises that retrain how the muscles around the shoulder blade fire and coordinate, not just strengthening them.
Posterior Shoulder Instability
The shoulder is the most frequently dislocated major joint in the body, and while most instability problems affect the front of the shoulder, posterior instability happens too. This occurs when the ligaments and capsule at the back of the joint become stretched or torn, allowing the ball of the joint to shift backward in the socket. It can result from a single traumatic event or, more commonly, from repetitive microtrauma in athletes who load the shoulder in forward-flexed positions, like offensive linemen in football or bench press enthusiasts.
Posterior instability often produces vague, hard-to-pinpoint pain in the back of the shoulder rather than a clear sensation of the joint slipping. You might feel a catch, a click, or a dead-arm sensation during certain movements. Clinical tests for this condition involve specific provocative maneuvers that push the humeral head backward in the socket, but these are best performed by a clinician who can interpret the results alongside imaging.
How to Narrow Down the Cause
A few patterns can help you figure out what’s going on before you see someone about it. Pain that builds gradually, worsens with overhead reaching, and disrupts your sleep when you roll onto that side points toward the rotator cuff. Pain that’s sharp or burning and travels with tingling or numbness into your arm, especially if neck movements change the pain, suggests a nerve issue in the cervical spine. Deep, constant aching right behind the shoulder blade that doesn’t clearly link to specific arm movements could indicate nerve compression at the shoulder itself.
Pay attention to what makes the pain better or worse. Rotator cuff problems hurt more with specific movements and improve with rest. Nerve-related pain can be constant and may not respond predictably to position changes, except for the hand-on-head relief pattern seen with cervical radiculopathy. Pain that’s worst during overhead sports or repetitive throwing and comes with noticeable weakness when rotating the arm outward is worth getting evaluated sooner, since it could indicate a tear or nerve injury that benefits from early treatment rather than waiting it out.