What are the shoulder blades and where they are located?
The shoulder blades are two flat, triangular bones on each side of the top of your back. They are connected to the upper arm bones (humerus), collar bones (clavicle) and the muscles of the upper back, neck and arm.
What causes shoulder blade pain?
Pain in the shoulder blades can be caused by bad posture, psychological stress, shoulder overuse, injuries, pinched spinal nerves, lung diseases and disorders of other chest and abdominal organs.
The following conditions typically, but not exclusively, cause pain only in the right or only in the left shoulder blade or only between them:
- RIGHT shoulder blade pain: gallstones, liver cancer, pelvic inflammatory disease, rupture of an abdominal organ: stomach, appendix, spleen, ovary or ovarian tube (in ectopic pregnancy)
- LEFT shoulder blade pain: irritable bowel syndrome (IBS), heart, pancreas and spleen conditions
- Pain BETWEEN the shoulder blades: gastroesophageal reflux disease (GERD), esophageal cancer, broken vertebra (in osteoporosis or bone cancer), Hodgkin lymphoma, aortic dissection
Picture 1. Shoulder blade pain location
Causes of Shoulder Blade Pain by Organ
1. Poor Posture (Forward or Rounded Shoulders)
Rounded shoulders can result from the tight chest and weak upper back muscles, for example, due to a long-term desk job, and can cause pain in the shoulder blades or between them . Pain can be triggered by bending the head forwards.
2. Emotional Stress
Chronic emotional stress, anxiety or depression can result in an increased tension in your upper back muscles with burning or stabbing pain between the shoulder blades; the pain can be triggered by touching the chest with the chin, deep breathing or stretching the back muscles [89,90].
Myofascial pain syndrome is a chronic condition with palpable knots in the muscle sheaths (fascia) that act as trigger points. Snapping on the muscle knots in the shoulder blade area triggers muscle twitches at the site of the snap and deep aches in the shoulder, the back side of the arm, hand and little and ring finger (Picture 2) .
Picture 2. Myofascial pain syndrome: Applying pressure on a trigger point can cause pain over the shoulder blade that radiates down the arm.
Serratus anterior muscles on both sides of your chest help raise your upper arms forward and upward, for example, during boxing sprinting and workout exercises (push-ups, bench presses). Symptoms of overuse include:
- Pain at the bottom of the shoulder blades, below the armpits and on the inner sides of the arms down to the pinky and ring finger (Picture 3)
- Aggravation of pain by deep breathing 
4. Muscle Strain (Pulled Muscle) or Tear
Muscle strain refers to overstretching and muscle tear to a rupture of a muscle, such as during carrying a heavy backpack, reaching for something on a high shelf, push-ups, pull-ups, weightlifting (deadlift, bench press, squat) or similar activities. Symptoms include tenderness, pain and swelling in the shoulder blade area .
5. Muscle Contusion (Bruise)
Muscle contusion is a collection of the blood in a muscle (hematoma), usually caused by a direct blow or fall . Symptoms include localized swelling, bruising (reddish-bluish discoloration), tenderness and pain.
6. Snapping Scapula Syndrome
Snapping scapula syndrome refers to snapping, grinding or popping sound during shrugging or lifting an arm sideways due to rubbing of the shoulder blade against the rib cage. Other symptoms can include palpable crepitus over the medial side of the scapula, and pain between the shoulder blades when lifting the arm above the shoulder level .
Causes and risk factors include repeated overhead arm movements, like in swimming or throwing, weak upper back muscles and scapular dyskinesia .
7. SICK Scapula Syndrome
SICK scapula syndrome (scapular malposition, inferior medial border prominence, coracoid pain and malposition, and dyskinesis of scapular movement) includes :
- Asymmetric shoulder blades and prominent inferior medial angle of the affected shoulder blade
- Pain in the shoulder blade area and upper outer part of the arm, aggravated by using the arm force against resistance
- Tenderness along the medial shoulder blade border
- Normal or slightly reduced range of shoulder motion
The syndrome can develop in overhead throwing athletes, such as baseball, tennis and water polo players, javelin throwers, shot putters and swimmers.
1. Whiplash – Neck Strain and Sprain
Whiplash is a strain or tear of the neck muscles, tendons or ligaments or even a damage of the spinal discs and nerves caused by a sudden neck movement backward and forward, most commonly in rear-end car accidents and motorbike falls. Symptoms can include :
- Pain radiating from the neck toward the shoulder blades; the pain can be triggered by turning the head sideways
- Neck stiffness
- Dizziness and headache
Typically, more than 10 symmetrical tender points can be found: on the bottom of the back of the head, above the shoulder blades, on the upper parts of the buttocks, over the upper part of the breastbone, on the hips, elbows and knees (Picture 4) .
Fibromyalgia affects mainly women; it can develop after an accident, disease or stressful event or without an apparent reason.
Picture 4. Tender points in fibromyalgia
Shoulder blade fracture can occur during a fall on an extended arm or due to a direct hit to the shoulder blade. Symptoms can include:
- Sudden, extreme, sharp pain, and an audible click in the shoulder blade
- The pain that can radiate into the neck or upper arm and can be aggravated by moving an arm, firmly pressing on a shoulder blade or sleeping on the back 
- A visible deformity and swelling
Vertebral fractures are most common in older people with osteoporosis or spinal cancer and can be triggered by minor accidents or even by a hard cough . Diagnosis can be confirmed by an X-ray.
2. Scapular Cancer
Bone cancer or the spread of a lung or other cancer into the shoulder blade can cause shoulder blade tenderness and pain, especially when sleeping on the back, fatigue, loss of appetite and weight.
1. Pinched Spinal Nerves
Pinched nerves arising from the neck spinal cord can cause burning and shooting pain and tingling:
- C4, C5 and C6 nerve roots: above the shoulder blade [2,92]
- C7 and C8 nerve roots: between the shoulder blades 
- C8 nerve roots: in the right or left shoulder blade area 
The pain can be triggered by bending the neck backward, turning the head sideways, or lying down. The pain can spread to the back of the neck and head or down the arm all the way to the fingers . It can be relieved by placing a hand on the top of the head . Common causes include bulging or herniated discs due to an injury, degenerative disc disease, spinal wear and tear (spinal osteoarthritis or spondylosis) 
Cervical spinal stenosis (compression of the spinal cord by a herniated disc) can cause pain in the upper back between the shoulder blades .
2. T4 Syndrome or Upper Thoracic Syndrome
- Pain and stiffness between the shoulder blades and in the neck
- Chest tightness and abnormal sensations (a sense of swelling, extreme perception of cold and heat, numbness and tingling) in hand, all 5 fingers and forearm (Picture 5); the symptoms are not aggravated by the trunk or arm movements [79,87].
Causes include repetitive forward, backward and sideways bending or twisting of the trunk (in dentists, surgeons, electricians, assembly-line workers) or carrying heavy backpacks . Pain can be relieved by laying flat (without a pillow) on the back .
Picture 5. T4 or “upper thoracic syndrome” pain distribution
3. Shingles (Herpes zoster)
A reactivation of a previous infection with the Herpes-zoster virus can cause burning pain followed by red, itchy blisters in the form of a stripe that runs horizontally from the spinal line toward the front of the chest, usually only on one side . The pain and rash can persist for several weeks or months.
4. Long Thoracic Nerve Injury (Winging Scapula)
The long thoracic nerve travels from the armpit vertically down the side of the chest on each side and supplies the serratus anterior muscle. It can be damaged by a direct blow to the side of the ribs, sustained bearing of heavy loads over the shoulder, deep massage or during removal of a breast and the lymph nodes in the armpit (radical mastectomy). Symptoms can include:
- Trouble lifting the arm on the affected side forward and above the shoulder level
- Winging scapula (a shoulder blade that sticks out)
- Mild burning pain on the side of the chest and in the scapular area.
Recovery time may be up to 2 years [72,82,83].
V. CHEST ORGANS
1. Gastric Reflux
Gastro-esophageal reflux disease (GERD) and bile reflux symptoms can include:
- Heartburn — a burning sensation behind the breastbone
- Pain between the shoulder blades that tends to be worse after eating, especially when lying down after a meal
- Sour or metallic taste in mouth 
Pleurisy is an inflammation of the lung membrane (pleura) caused by a viral infection, such as flu, bacterial infection, such as pneumonia, cancer, drugs, etc. . Symptoms may last from few days to 2 weeks or more and can include stabbing pain on one or both sides of the chest or upper back that is worse during breathing in, coughing and sneezing .
Pneumothorax–a rupture of the lung membrane that results in the collapse of the lung, usually on one side–can cause sudden knife-like pain on one side of the chest, followed by vague pains around the chest and shoulder blades, worsened by breathing, coughing and moving the arms .
4. Coronary Heart Disease and Heart Attack
The risk of coronary heart disease increases in men after 45 and in women after 55 . Typical symptoms include:
- Sudden, heavy, burning pain behind the breastbone (angina) and shortness of breath aggravated by exercise, stress, cold or heavy meal and relieved by rest or the analgesic nitroglycerin, and lasting for less than 5 minutes
- The pain can radiate to the neck, jaw, into the left, both or between the shoulder blades or down the inner side of the left arm to the fingers .
Pain from a heart attack is similar to angina but much stronger and longer (>15 minutes); in men can radiate to the neck, chin, left shoulder and down the left arm and in women into the neck, chin, both shoulder blades or arms .
VI. REFERRED PAIN FROM THE ABDOMINAL ORGANS
Disorders of abdominal organs that irritate the diaphragm (the flat muscle between the chest and abdominal cavity) can cause pain in the left or right shoulder. This occurs because the phrenic nerve, which conducts sensory stimuli from the diaphragm, and the nerves that conduct sensory stimuli from the shoulders, convey the information to the brain via the same pathways, so the brain can wrongly interpret the pain origin . Sometimes, only shoulder pain without abdominal pain is present . Referred shoulder pain is not aggravated by shoulder movements .
1. Trapped Gas
In individuals with irritable bowel syndrome or constipation, trapped gas in the part of the colon near the spleen can cause pain on the left side of the upper abdomen, chest and left shoulder (splenic flexure syndrome); the pain is constant, can be severe and can last for several hours .
After laparoscopy (an endoscopic investigation of the abdominal cavity) or hysteroscopy (an endoscopic investigation of the uterus), some of the gas that has been insufflated into the abdominal cavity during the procedures can get trapped under the diaphragm and cause sharp pain in one or both shoulder blades. The pain can last for few days; laying flat can relieve pain [52,53]. After the colonoscopy, a pain in the left shoulder blade is common .
2. Gallbladder Disease
Gallstones with or without acute inflammation of the gallbladder (cholecystitis) can cause “biliary colic” with [47,48,49]:
- Sudden, severe pain below the rib cage on the right side persisting from few minutes to several hours, which often appears after eating and can radiate to the right flank or beneath or below the right shoulder blade or to the shoulder tip
- Other symptoms, such as nausea, vomiting or fever
Gallstones in the common bile duct can present with additional symptoms, such as jaundice, pale and smelly stools and dark urine . Gallbladder dyskinesia and sphincter of Oddi dysfunction can cause similar pain, which can persist after a gallbladder removal .
3. Irritation of the Diaphragm
In peritonitis (inflammation of the abdominal membrane), pus can collect beneath the diaphragm (subphrenic abscess) and cause severe abdominal pain and tenderness, pain at the tip of the shoulder blade and fever .
Ruptured ectopic pregnancy with abdominal bleeding can cause a sudden, sharp pain in the lower left or right abdomen and at the tip of the shoulder blade .
A ruptured ovarian cyst can cause lower right or left abdominal pain and pain at the tip of the shoulder blade .
In endometriosis, abdominal pain and the pain at the tip of the shoulder blade can be worse during ovulation and period [3,17].
VII. SHOULDER PAIN
This section describes the conditions that cause pain in the front of the shoulder and upper arm rather than in the shoulder blades.
1. Rotator Cuff Tendonitis and Tear
The rotator cuff is a collective term for the muscles that move the shoulder. Inflammation of the rotator cuff tendons or impingement syndrome is common in sports with overhead arm movements, such as tennis, golf, throwing (“thrower’s shoulder”), swimming (“swimmer’s shoulder”) and in jobs, like the painting. A sharp pain in the front of the shoulder and outer side of the upper arm radiating to the hand, and spasm of the shoulder muscles usually develops over the months [35,91]. Pain is aggravated by lifting an arm over the levels of the shoulder . Rotator cuff tear results in similar symptoms; chronic tear can cause a popping sound during moving a shoulder [35,93].
Shoulder overuse can also result in tenosynovitis (inflammation of the tendon sheets) or bursitis (inflammation of the fluid-filled sac called subacromial bursa) with swollen red skin over the tip of the shoulder that is sore and warm to the touch [1,30].
2. Calcific Tendonitis
Calcific tendinitis, a chronic inflammation of rotator cuff tendons of unknown cause, can cause mild or severe and sharp pain in the shoulder and upper arm that comes and goes, stiffness, catching or snapping in the shoulder [7,35].
3. Adhesive Capsulitis (Frozen Shoulder)
Adhesive capsulitis is an inflammation and thickening of the shoulder capsule, which wraps the shoulder joint. Causes include shoulder immobilization, diabetes, hypothyroidism and hyperthyroidism. It can gradually develop in adults over 40 and cause a deep ache in one shoulder and upper arm and severe stiffness with a limited range of motion of the shoulder . The condition usually spontaneously resolves within 1-2 years.
4. Arthritis of the Shoulder Joint
Common types of the shoulder arthritis (inflammation of the shoulder joint) are rheumatoid arthritis, osteoarthritis, post-traumatic arthritis and arthritis in systemic lupus erythematosus and got . Symptoms can include severe pain in the shoulder and entire arm and, sometimes, swelling, warmth and redness of the shoulder and a popping sound when moving the shoulder; pain can become worse by weather change [35,97].
5. Shoulder Sprain, Subluxation and Dislocation
Shoulder sprain means overstretching or rupture of the shoulder joint capsule, which can be caused by falling on an outstretched arm, a direct blow to the shoulder or overuse of the shoulder . Symptoms include pain in the shoulder and upper arm, tenderness, shoulder joint instability and swelling or bruising around the shoulder . Shoulder dislocation and subluxation (partial dislocation) can cause similar symptoms.
6. Brachial Neuritis
Brachial neuritis, also called Parsonage-Turner syndrome (PTS), is a rare neurological condition of uncertain cause, which may include infection, vaccination (flu, tetanus, hepatitis B), surgery or trauma [60,75]. Symptoms include sudden burning pain in the shoulder and upper arm. The pain lasts from a day to several weeks and is usually followed by an abnormal protrusion of the shoulder blade (scapular winging) and weakness, paralysis, tingling or numbness in an arm or hand. Recovery may last from few months to years.
7. Other Causes of Shoulder Pain
Other causes of shoulder pain include thoracic outlet syndrome, polymyalgia rheumatica, polymyositis and dermatomyositis, lung cancer and avascular necrosis of the humeral head.
How to treat shoulder blade pain?
In an early, painful phase of a shoulder or shoulder blade injury, shoulder rest prevents further damage.
To reduce pain, swelling or bruising, put ice in a plastic bag, wrap it in a cloth and hold over the painful area for up to 20 minutes, several times a day.
Heat pads can help relieve pain in myofascial pain syndrome due to increased tension of the upper back muscles.
Dry needling can help in myofascial pain syndrome, but the effect is temporary.
Vapocoolant spray can reduce the pain in muscle strain or bruise and before myofascial pain release.
A Sling or a Shoulder Brace
A sling prevents the motion of the shoulder blade and shoulder and encourages their healing after a fracture, dislocation, rotator cuff injury or surgery. A doctor can prescribe a shoulder brace in shoulder joint instability and impingement syndrome .
Scapular Stretching (Retraction) Exercises
Shoulder blade exercises are intended to relieve pain due to the tension of the upper back muscles or to prevent stiffness of the shoulder joint after injury. Do not exercise immediately after an injury or when you have severe pain.
- Non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, can be used to relieve mild to moderate pain.
- Muscle relaxants can help in muscle spasms near the spine caused by a herniated disc.
- Steroids can be used to treat inflammation in disorders, such as rheumatoid arthritis, polymyalgia rheumatica , polymyositis  and brachial neuritis .
Surgical treatment may be needed for pinched nerves, broken shoulder blade, calcific tendonitis, adhesive capsulitis and snapping scapula syndrome.
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