A sac the thickness of paper, causing pain everyone blames on the neck.

SUBACROMIAL BURSA

A fluid sac the thickness of paper sits between your rotator cuff and the bone above it. When it is the problem, the pain is felt in the upper arm and blamed on the neck.

Where the pain actually goes

Subacromial pain is felt over the outer shoulder and the upper third of the arm, often stopping around the deltoid insertion. It rarely goes past the elbow and almost never reaches the hand. That distribution is the first thing that separates it from a C5 or C6 root problem, which travels the whole way down.

The second thing is what provokes it. Reaching overhead, reaching behind the back, and lying on that side at night are the subacromial trio. Turning the head is not.

The painful arc, and what it means

Pain through roughly the middle of the elevation range that eases at the top is the classic sign, and it happens because the cuff and bursa are compressed under the acromion in that arc. It is one of the more useful physical findings in shoulder medicine, though like every isolated test it is more convincing as part of a cluster than on its own.

Weakness on resisted abduction that is limited by pain rather than by loss of power is bursa or tendon. Weakness that is present without pain is a different question and raises a cuff tear or a nerve problem.

Why this page exists on a neck website

Because the overlap runs both ways and it is well documented. A systematic review of overlapping, masquerading and causative cervical spine and shoulder pathology exists precisely because clinicians keep treating one when the driver is the other. A person can have a degenerate neck on imaging and a subacromial problem generating every symptom they actually feel — and then have their neck treated for a year.

Our position is that the shoulder gets examined at the neck appointment, every time. It takes two minutes and it changes the plan often enough to justify itself many times over.

What treatment looks like

Loaded rotator cuff rehabilitation is the backbone and it has a substantial evidence base. It is not gentle stretching — it is progressive strengthening, and the people who do it properly get the durable results.

A subacromial corticosteroid injection has a role: it is useful for confirming the source and for opening a window in which rehabilitation becomes possible. It is not a treatment in its own right and repeated injection into a tendon environment is not a plan. Where a bursa is genuinely inflamed and a person cannot begin rehabilitation because of it, one well-placed injection is a reasonable and evidence-supported step.

When it is not the bursa

• Night pain with true weakness and a positive lag sign — think cuff tear, and imaging is warranted.
• Pain past the elbow, or into the hand — think neck.
• A stiff shoulder with restricted passive external rotation — that is adhesive capsulitis, not impingement, and it is treated differently.
• Pain localized to the top of the shoulder at the joint line — that is the AC joint.

The night pain question

Lying on the affected side compresses the bursa directly, and lying on the other side lets the arm fall forward into the same position. Both hurt, which is why shoulder pain wrecks sleep more reliably than neck pain does.

A pillow under the affected arm when lying on the good side, and a pillow behind the back to stop rolling onto the bad one, does more than most people expect. It is not a treatment for the underlying problem, but sleep affects pain enough to be worth arranging deliberately.

What the terminology confusion costs

Impingement, subacromial pain syndrome, bursitis and rotator cuff tendinopathy overlap heavily and are used interchangeably by different clinicians. Guidelines have moved toward the broader descriptive term because the older mechanical model did not survive close examination.

The practical result is that two people can be told two different diagnoses for the same shoulder. What matters more than the label is whether the treatment is progressive loading, because that is what the evidence supports regardless of which name is used.

The injection question, answered properly

Guidelines from multidisciplinary groups have been fairly consistent: corticosteroid injection gives short-term relief, exercise gives durable relief, and the combination is more useful than either used as a substitute for the other. Trials comparing corticosteroid injection, physical therapy and combined treatment in chronic shoulder pain exist and support that reading.

Our practical rule is that an injection needs a job. If the job is to let somebody sleep and start loading, that is a good job. If the job is to be the treatment, it is the wrong tool and repeating it will make that clear over about a year.

What the shoulder examination adds to a neck appointment

Passive versus active range, which separates a stiff joint from a painful one. Resisted testing in the specific planes, which localizes to the cuff. The painful arc. Palpation of the AC joint. And the cervical provocation tests done immediately alongside, so the two are compared in the same few minutes rather than in appointments six weeks apart.

Doing them together is the whole point. A person who has seen a shoulder service and a neck service separately has had both examinations, and still nobody has compared them.

What people ask about shoulder-versus-neck pain

My MRI showed bursitis. Is that my answer?

Not necessarily. Bursal signal change is common on imaging and needs to match your examination and your pain distribution before it earns the diagnosis. AC joint pain.

Can my neck cause shoulder pain?

Yes, and this is exactly the confusion. C5 refers to the outer shoulder convincingly. The provocation pattern and how far the pain travels are what separate them. Neck or shoulder?. C5 refers to the outer shoulder and stops at the elbow, which is the tell.

Is an injection going to weaken my tendon?

Repeated injections into a tendon environment are a genuine concern, which is why we use them to open a rehabilitation window rather than as an ongoing treatment. Rotator cuff, or the neck?.

How long does rehabilitation take?

Three months of consistent loaded work before judging it. Most people who report failure stopped at four weeks. How long neck pain should take to settle.

Related reading

• Rotator cuff, or the neck?
• AC joint pain
• Cervical radiculopathy
• Shoulder pain that starts in the neck
• Thoracic outlet syndrome
• Why your MRI does not explain it