Shoulder Injuries, Part 3: Rotator Cuff, Examination and Diagnosis
The rotator cuff plays a central role in shoulder movement, strength, and dynamic control. In Part 3, we examine the four rotator cuff muscles, their anatomy and function, and how rotator cuff-related problems can contribute to shoulder pain and loss of function.
We will then move from anatomy into clinical assessment. Shoulder pain can arise from many different structures and mechanisms, and individual examination findings rarely provide the entire answer. An effective assessment combines the patient's history with observation, range of motion, strength and neurological testing, selected orthopedic tests, and consideration of the activities and loads that reproduce symptoms.
Diagnostic imaging can provide valuable information when clinically indicated, but imaging findings must be interpreted alongside the patient's symptoms and examination. The goal is not simply to identify an abnormal structure, but to develop a clinically meaningful diagnosis that can guide appropriate treatment and rehabilitation.
Article Index:
Introduction
Rotator cuff injuries frequently occur among athletes and non-athletes, making early diagnosis crucial for determining causative factors, initiating appropriate treatment, and preventing additional injury.
The rotator cuff comprises four primary muscles and their corresponding tendons, which include:
Supraspinatus
Infraspinatus
Teres minor
Subscapularis
The rotator cuff muscles are frequently called the SITS muscles (an acronym derived from the initial letter of each muscle). This group facilitates various upper limb movements such as flexion, abduction, internal, and external rotation.
Anatomy & Biomechanics
The rotator cuff consists of four muscles and their tendons that surround the glenohumeral joint:
Supraspinatus
Infraspinatus
Teres Minor
Subscapularis
Together, these muscles are sometimes referred to as the SITS muscles, using the first letter of each muscle. Their role extends beyond simply producing movement. The rotator cuff contributes to abduction and internal and external rotation of the arm while also providing dynamic control of the humeral head as the shoulder moves.
Supraspinatus Muscle
Origin: Supraspinous fossa of the scapula
Insertion: Superior facet of the greater tubercle of the humerus
Primary Function: Contributes to shoulder abduction and glenohumeral stability
Innervation: Suprascapular nerve (C5-C6)
Infraspinatus Muscle
Origin: Infraspinous fossa of the scapula
Insertion: Middle facet of the greater tubercle of the humerus
Primary Function: External rotation of the humerus and glenohumeral stability
Innervation: Suprascapular nerve (C5-C6)
Teres minor Muscle
Origin: Lateral border of the scapula
Insertion: Inferior facet of the greater tubercle of the humerus
Primary Function: External rotation of the humerus and glenohumeral stability
Innervation: Axillary nerve (C5-C6)
Subscapularis muscle
Origin: Subscapular fossa of the scapula
Insertion: Lesser tubercle of the humerus
Primary Function: Internal rotation and adduction of the humerus and glenohumeral stability
Innervation: Upper and lower subscapular nerves, predominantly C5-C6, with variable C7 contribution described in anatomical sources.
Dynamic Stability of the Shoulder
One of the most important functions of the rotator cuff is to provide dynamic stability of the glenohumeral joint. Because the humeral head articulates with the relatively shallow glenoid, muscular control is essential as the arm moves through large ranges of motion.
Rather than functioning independently, the rotator cuff muscles work together with the deltoid and other shoulder muscles to create coordinated force couples. The subscapularis anteriorly is balanced by the infraspinatus and teres minor posteriorly, while the cuff as a whole helps compress and control the humeral head within the glenoid during arm movement.
During shoulder elevation, the deltoid generates a substantial superiorly directed force. Coordinated rotator cuff activity contributes compression and opposing force components that help maintain a stable centre of rotation rather than simply allowing the humeral head to translate superiorly. This interaction illustrates why normal shoulder function depends on the coordinated activity of the entire rotator cuff, rather than any single muscle acting in isolation.
Fascial Connections
The muscles of the shoulder do not function as completely isolated structures. They are surrounded and interconnected by layers of connective tissue that blend with muscle epimysium, tendons, periosteum, intermuscular septa, and the deeper fascia of adjacent regions. Anatomical studies of the upper extremity demonstrate continuity between these fascial structures and muscular attachments.
Fascia is also more than passive wrapping. Deep fascia contains sensory innervation, including proprioceptive and nociceptive nerve endings, and connective tissues can participate in the transmission and distribution of mechanical forces. The extent and clinical importance of force transmission between more distant regions, however, remains an active area of research.
Regional Connections
Around the shoulder, fascial and connective-tissue relationships extend between the rotator cuff, scapular muscles, deltoid, pectoral region, and upper arm. Anatomical studies also demonstrate myofascial continuity along portions of the upper extremity, including connections involving the infraspinatus and teres minor posteriorly and the pectoral and brachial fascia anteriorly.
These anatomical relationships provide one way of understanding how forces generated by muscles can be distributed through surrounding connective tissues during movement. They also reinforce an important clinical principle: the shoulder should not always be assessed as an isolated structure.
However, anatomical connection does not automatically establish clinical causation. Neck pain, arm pain, altered shoulder movement, or other symptoms should not be attributed to a fascial restriction simply because anatomical continuity exists between those regions. Neurological, musculoskeletal, vascular, referred, and other potential sources of symptoms must also be considered.
For clinicians using a fascial approach, these connections can therefore contribute to the examination and treatment framework, but they should be interpreted alongside the patient's history, neurological findings, mobility, strength, symptom behavior, and functional demands.
Rotator Cuff Injuries
Rotator cuff disorders are common and can develop through a combination of age-related tendon changes, repetitive or high-load activity, acute trauma, and individual health factors. An injury may occur suddenly, such as during a fall, shoulder dislocation, or forceful movement, while other rotator cuff problems develop gradually without a single identifiable event.
Common rotator cuff conditions include:
Rotator cuff tendinopathy
Partial-thickness rotator cuff tears
Full-thickness rotator cuff tears
Acute traumatic rotator cuff injuries
Rotator cuff-related shoulder pain (RCRSP)
Age is an important factor in rotator cuff structural changes and tears. Metabolic and cardiovascular factors may also influence tendon health. Diabetes and hyperlipidemia, for example, have been associated with increased rates of rotator cuff disease, while smoking has been associated with rotator cuff pathology and poorer tendon healing in portions of the literature. These are risk associations rather than proof that any one factor caused an individual's shoulder problem.
Symptoms of a Rotator Cuff Injury
The presentation varies according to the condition, severity, mechanism of injury, and individual. Common findings may include:
Pain with reaching or overhead activities
Pain when lifting or lowering the arm
Night pain, particularly when lying on the affected shoulder
Pain or weakness with resisted shoulder movement
Reduced strength or endurance
Difficulty performing work, sport, or daily activities
Reduced active range of motion
Clicking, catching, or stiffness in some patients
A sudden traumatic tear may produce immediate pain and weakness, while degenerative tears and tendinopathy may develop more gradually. Importantly, pain location alone cannot reliably identify which rotator cuff tendon is involved, and structural abnormalities can also be present without symptoms.
The Painful Arc
The Painful Arc Test assesses whether pain occurs during active shoulder elevation, commonly through the middle portion of abduction. A positive painful arc can increase suspicion of rotator cuff-related or subacromial shoulder pain, but it does not identify a specific injured structure and should not be used alone to diagnose “impingement.” Clinical studies show that individual shoulder tests generally have limited diagnostic accuracy when used in isolation.
The painful arc becomes more useful when interpreted alongside the history, range of motion, strength testing, other selected examination findings, and, when clinically indicated, diagnostic imaging.
Characterizing Shoulder Pain
A careful history remains one of the most important parts of the shoulder examination. When evaluating pain, consider:
Location: Where is the pain felt?
Radiation: Does it travel into the arm, neck, chest, or upper back?
Quality: Is it aching, sharp, burning, throbbing, or another sensation?
Severity and functional impact: What activities are limited?
Onset and mechanism: Did symptoms begin suddenly or gradually? Was there an injury?
Aggravating factors: Which movements, positions, loads, or activities reproduce symptoms?
Relieving factors: What reduces the symptoms?
Timing: Is the pain intermittent or constant? Is it worse at night?
Associated symptoms: Is there weakness, numbness, tingling, instability, swelling, or loss of motion?
Physical Examination
A thorough shoulder assessment begins with the patient's history and a clinical examination directed by the presenting symptoms and mechanism of injury. The examination may include observation, active and passive range of motion, strength testing, selected orthopedic procedures, neurological assessment, and vascular examination when clinically indicated.
The clinician should also determine whether the presentation is consistent with a musculoskeletal shoulder disorder or whether symptoms could represent neurological, vascular, visceral, systemic, or other potentially serious pathology requiring further investigation or referral.
Diagnostic imaging is not automatically required for every patient with shoulder pain. Imaging should be selected according to the history, examination findings, suspected pathology, severity and duration of symptoms, and whether the result is likely to change clinical management. In acute traumatic shoulder pain, radiographs are generally the initial imaging study. When a rotator cuff tear is suspected and radiographs are negative or inconclusive, ultrasound or MRI may provide additional information.
For chronic shoulder pain, imaging decisions should similarly be guided by the suspected condition rather than by age or an arbitrary period of unsuccessful treatment. When rotator cuff pathology is suspected following normal or inconclusive radiographs, ultrasound and MRI are among the appropriate options.
Orthopedic Evaluation
Orthopedic examination procedures can help identify patterns consistent with rotator cuff-related shoulder pain, instability, acromioclavicular disorders, restricted mobility, and other potential sources of shoulder symptoms.
However, individual orthopedic tests rarely provide a definitive diagnosis on their own. Their findings are more useful when interpreted alongside the patient's history, symptom behavior, range of motion, strength, neurological findings, and other examination results.
Click the image to watch the Shoulder Orthopedic Evaluation video, which demonstrates several examination procedures commonly used when assessing shoulder pain.
Upper Limb Neuro Exam
A neurological examination should be considered when symptoms or clinical findings suggest possible involvement of the cervical spine, nerve roots, brachial plexus, or peripheral nerves.
Assessment may include muscle strength, reflexes, sensation, and selected peripheral nerve or neural provocation procedures. Neurological findings should be interpreted in conjunction with the patient's history and the remainder of the musculoskeletal examination.
Click the image to watch the Upper Limb Neurological Examination video.impairment of the nervous system.
Peripheral Vascular Examination - Key Points
Vascular assessment may be appropriate when the history or examination raises concern about altered circulation to the upper extremity. Findings such as unusual swelling, changes in skin colour or temperature, diminished pulses, or symptoms suggesting vascular compromise require appropriate investigation and, when indicated, medical referral.
A peripheral vascular examination can include observation of the extremity, palpation of pulses, comparison between sides, and other procedures selected according to the clinical presentation.
Click the image to watch the Peripheral Vascular Examination video.
Imaging
Diagnostic imaging can provide valuable information when the patient's history and physical examination suggest that further investigation is needed. The choice of imaging should be guided by the suspected condition and by whether the findings are likely to influence diagnosis, treatment, or referral.
Different imaging modalities provide different types of information:
X-rays: Often the initial imaging study when fracture, dislocation, arthritis, calcification, or other bony abnormalities are suspected.
Ultrasound: Provides real-time assessment of the rotator cuff tendons, long head of the biceps tendon, bursa, and other superficial soft tissues. It can be particularly useful when evaluating suspected rotator cuff tears or tendinopathy.
MRI: Provides detailed visualization of the rotator cuff, muscles, labrum, cartilage, capsule, bone marrow, and other soft tissues. MRI can help characterize rotator cuff tears and identify associated shoulder pathology.
CT: Provides excellent visualization of bone and may be particularly useful for complex fractures, bone loss, and other conditions requiring detailed assessment of osseous anatomy.
MR or CT Arthrography: May be appropriate in selected cases, particularly when more detailed assessment of structures such as the labrum is required.
For acute shoulder pain with examination findings suggesting a rotator cuff tear and negative or inconclusive radiographs, both ultrasound and MRI without contrast are considered appropriate next imaging options. Similarly, for chronic shoulder pain with suspected rotator cuff pathology after normal or inconclusive radiographs, ultrasound and MRI are among the appropriate imaging choices.
Imaging Findings Must Be Interpreted Clinically
An important limitation of shoulder imaging is that structural abnormalities do not always correspond with pain. Rotator cuff abnormalities, including partial- and full-thickness tears, can be identified in people who have no shoulder symptoms, and their prevalence generally increases with age. A recent 2025 systematic review likewise found substantial rates of rotator cuff imaging abnormalities in asymptomatic shoulders, although the estimates varied considerably between studies and the certainty of evidence was low to very low.
For this reason, imaging findings should always be interpreted alongside the patient's history, symptoms, physical examination, functional limitations, and clinical goals. An abnormal image does not necessarily identify the source of the patient's pain.
Differential Diagnosis
Shoulder pain can arise from structures within the shoulder itself or be referred from the cervical spine, nervous system, cardiovascular system, and other regions. A differential diagnosis should therefore consider the patient's history, mechanism of injury, pain distribution, range of motion, strength, neurological findings, associated symptoms, and relevant medical history.
Conditions that may need to be considered include:
Acromioclavicular Joint Injury or Disorder: AC joint sprains, separations, and degenerative changes can produce localized superior shoulder pain, tenderness, and pain with movements that load the joint.
Adhesive Capsulitis: Commonly known as frozen shoulder, adhesive capsulitis typically produces progressive pain and substantial restriction of both active and passive glenohumeral motion, particularly external rotation.
Long Head of the Biceps Tendinopathy: Disorders involving the long head of the biceps tendon can contribute to anterior shoulder pain and symptoms associated with lifting, reaching, or other loading activities.
Subacromial-Subdeltoid Bursal Disorders: Irritation or inflammation of the bursa may accompany rotator cuff-related shoulder pain and can contribute to pain during shoulder movement.
Calcific Rotator Cuff Tendinopathy: Calcium deposits within a rotator cuff tendon, most commonly the supraspinatus, may be asymptomatic or produce episodes of significant shoulder pain and restricted movement.
Cervical Spine and Nerve Root Disorders: Cervical radiculopathy, degenerative cervical conditions, and other cervical disorders can produce pain perceived around the shoulder and may also cause radiating arm pain, numbness, tingling, altered reflexes, or weakness.
Glenohumeral Instability and Capsuloligamentous Injury: Traumatic or atraumatic instability can produce pain, apprehension, recurrent subluxation or dislocation, and difficulty with particular shoulder positions or activities.
Glenoid Labral Injury: Labral disorders, including SLAP and Bankart lesions, may be associated with pain, instability, clicking, catching, or reduced performance, particularly following trauma or repetitive overhead activity. These symptoms are not specific to labral pathology and should be interpreted within the complete clinical presentation.
Cardiac and Other Visceral Referral: Shoulder or arm discomfort can occasionally originate outside the musculoskeletal system. Myocardial ischemia is an important example, particularly when shoulder or arm symptoms occur with chest discomfort, shortness of breath, sweating, nausea, unusual fatigue, or other concerning systemic symptoms. Such presentations require appropriate medical assessment.
Peripheral Nerve Disorders: Entrapment, traction, or injury involving peripheral nerves or the brachial plexus can produce shoulder or arm pain accompanied by sensory changes, weakness, or altered motor function.
Glenohumeral or Acromioclavicular Osteoarthritis: Degenerative joint changes may contribute to pain, stiffness, crepitus, and reduced motion. Imaging findings should be correlated with the clinical presentation because degenerative changes can also occur without significant symptoms.
Shoulder Dislocation or Subluxation: Traumatic instability may result in partial or complete displacement of the humeral head. Acute dislocation generally produces marked pain, deformity, and loss of shoulder function and requires appropriate medical management.
Rotator Cuff-Related Shoulder Pain: This broad clinical category includes presentations historically described as rotator cuff tendinopathy, subacromial pain syndrome, and “impingement.” Current evidence does not support assuming that these symptoms simply result from mechanical compression of the rotator cuff beneath the acromion. Assessment should instead consider tendon health, strength, load tolerance, movement, symptoms, and the broader clinical presentation.
Thoracic Outlet and Other Neurovascular Disorders: Symptoms involving the shoulder and upper extremity may occasionally arise from compression or irritation of neurological or vascular structures in the thoracic outlet region. Depending on the structures involved, symptoms may include pain, paresthesia, weakness, swelling, colour changes, temperature changes, or vascular findings. These presentations require careful differential assessment rather than relying on a single provocative test.
Looking Beyond the Shoulder
The presence of shoulder pain does not necessarily mean that the primary source of symptoms is located within the shoulder. Cervical radiculopathy, peripheral nerve disorders, vascular conditions, referred visceral pain, inflammatory disease, infection, fracture, and other less common but potentially serious conditions should be considered when the history or examination raises concern.
The purpose of differential diagnosis is therefore not simply to identify which shoulder structure is painful. It is to determine whether the presentation is consistent with a musculoskeletal shoulder disorder, identify other conditions that may explain the symptoms, and recognize when additional investigation or referral is appropriate.
CONCLUSION - PART 3
The rotator cuff plays an important role in shoulder movement, strength, and dynamic stability, but evaluating rotator cuff-related shoulder pain involves more than identifying an injured tendon. Symptoms can arise from multiple structures and mechanisms, and examination findings need to be interpreted within the context of the patient's history, function, activity demands, and overall clinical presentation.
A thorough assessment combines history, range of motion, strength testing, selected orthopedic procedures, neurological examination, and other investigations when indicated. Diagnostic imaging can provide valuable information, but structural findings do not always correspond with symptoms and should therefore be interpreted alongside the clinical examination.
Ultimately, the goal is not simply to identify an abnormal structure. It is to develop a clinically meaningful diagnosis, exclude important differential diagnoses, and determine which findings are most relevant to the patient's pain and loss of function.
In Part 4: Treatment, Exercise and Rehabilitation, we bring the series together by examining how manual therapy, exercise, progressive loading, and functional rehabilitation can be integrated into an individualized approach to shoulder recovery.
References - Part 3
American College of Radiology. ACR Appropriateness Criteria® Acute Shoulder Pain: 2024 Update. Journal of the American College of Radiology. 2025;22(5S):S36-S47.
American College of Radiology. ACR Appropriateness Criteria® Chronic Shoulder Pain: 2022 Update. Journal of the American College of Radiology. 2023;20(5S):S49-S69.
Gill TK, Shanahan EM, Allison D, Alcorn D, Hill CL. Prevalence of abnormalities on shoulder MRI in symptomatic and asymptomatic older adults. International Journal of Rheumatic Diseases. 2014;17(8):863-871.
Lewis J. Rotator cuff related shoulder pain: Assessment, management and uncertainties. Manual Therapy. 2016;23:57-68.
Park HB, Yokota A, Gill HS, El Rassi G, McFarland EG. Diagnostic accuracy of clinical tests for the different degrees of subacromial impingement syndrome. Journal of Bone and Joint Surgery American Volume. 2005;87(7):1446-1455.
Salamh PA, Hanney WJ, Boles T, et al. Is it time to normalize scapular dyskinesis? The incidence of scapular dyskinesis in those with and without symptoms: A systematic review of the literature. International Journal of Sports Physical Therapy. 2023;18(3):558-576.
Sciascia A, Kibler WB. Current views of scapular dyskinesis and its possible clinical relevance. International Journal of Sports Physical Therapy. 2022;17(2):117-130.
Wilke J, Krause F. Myofascial chains of the upper limb: A systematic review of anatomical studies. Clinical Anatomy. 2019;32(7):934-940.
Wilk KE, Macrina LC, Reinold MM. Non-operative rehabilitation for traumatic and atraumatic glenohumeral instability. North American Journal of Sports Physical Therapy. 2006;1(1):16-31.
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DR. BRIAN ABELSON, DC. - The Author
Dr. Brian Abelson is a chiropractor, author, and educator with more than 30 years of clinical experience in musculoskeletal care, rehabilitation, and sports performance. His educational work focuses on musculoskeletal conditions, human movement, sports biomechanics, and evidence-informed approaches to treatment and rehabilitation.
He is the developer of Motion Specific Release (MSR) and Clinical Director of Kinetic Health in Calgary, Alberta, Canada.
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