Which muscle internally rotates the shoulder

In the end, good posture and better biomechanics can lead to greater strength and less injury risk. Additionally, better posture often helps people feel better and more confident. Appointments Book with Dr. About About Dr. Patient Supplement Portal. Concussion Reset Course. Blog Brains, pains, and performance. Internal Rotation in the Gym This is a pet-peeve of mine. So here it goes. First, let's look at what we're even training when we do these exercises… What is my rotator cuff?

Supraspinatus ; helps pull your arm away from your body abduction Infraspinatus ; helps rotate your shoulder laterally externally and transversely abducts Teres Minor ; helps rotate your shoulder laterally externally and transversely abducts Subscapularis ; helps rotate your shoulder medially internally Again, all of these also help to stabilize the glenohumeral shoulder joint.

To train infraspinatus and teres minor You would work on external rotation exercises e. To train subscapularis You would work on internal rotation exercises e. To train supraspinatus You would work on initiation of shoulder abduction e.

Number 2 below is where I have my beef. The exceptions. If you are a professional arm wrestler, go for it! Takeaways for everyone. That's a win-win. Movement , Medicine Mark Heisig September 4, rotator cuff , gym , performance , movement.

Facebook 0 Twitter LinkedIn 0 0 Likes. Most cadaver studies have demonstrated a hypovascular area within the critical zone of the supraspinatustendon.

It has been suggested that this area of hypovascularity has a significant role in the attritional degeneration of the aging tendon. More recent studies of the microvascular supply to the supraspinatus tendon in symptomatic patients with impingement syndrome suggest that in the area of greatest impingement, i. In vivo analysis using orthagonal polarisation spectral imaging has demonstrated that there is good vascularity of supraspinatus, even in the critical zone in intact rotator cuffs [ Biberthaler et al.

A - capillaries within normal supraspinatus tendon. B - absent capillaries in the edges of a supraspinatus cuff tear. We will explore some of the biomechanical reasons for the development of cuff tears, rather than the differences between extrinsic and intrinsic causes.

Using finite element modelling of the rotator cuff the stress concentrations were studies in varying degrees of subacromial impingement. The stress concentrations were highest in the critical zone of the cuff with tears potentiating on the articular side, bursal side and intratendinous.

Articular side tears were slightly more common [ Mehta et al. Neer originally believed that rotator cuff tears arose fom a mechanical process secondary to progressive wear.

The morphology of the anterior acromion has been found to correlate with cuff tears. This has also been borne out by recent clinical studies where acromial morphology was found to be a predictor for cuff tears [ Gill et al.

JSES, ]. Bigliani classification of acromial morphology. Type 3 was more commonly associated with rotator cuff tears [ Bigliani, Clin Sports Med, ]. The triad of anterior capsular laxity, posterior contraction and internal impingement was originally described in overhead athletes [ Walch et al.

The internal impingement occurs when the cuff is pinched between the humeral head and the postero-superiorlabrum during extreme abduction and external rotation. This scuffs and abrades the articular surface of the cuff progressively leading to cuff tears. The rotator cuff appears to degenerate with age. More work needs to be done on the age-related changes of the rotator cuff, but the aging cuff is probably more prone to the extrinsic and intrinsic mechanisms.

The aetiological and pathomechanical factors in the development of rotator cuff tears appear to have multifactorial roots. An understanding of the anatomy, mechanics and the biology of the rotator cuff is essential to our treatment plans.

This is an interactive guide to help you find relevant patient information for your shoulder problem. This site complies with the HONcode standard for trustworthy health information: verify here. The material on this website is designed to support, not replace, the relationship that exists between ourselves and our patients. Full Disclaimer. I intend to cover: Cuff Mechanics Tendon Anatomy - layers, microanatomy, blood supply Pathomechanics of cuff tears Rotator cuff Muscles The shoulder complex comprises 30 muscles.

The rotator cuff muscles are: Supraspinatus Infraspinatus Teres Minor Subscapularis The tendons of these muscle coalesce to form the rotator cuff.

Supraspinatus Supraspinatus is not only an initiator of abduction, but acts throughout the range of abduction of the shoulder. Subscapularis Subscapularis is the main internal rotator of the shoulder. Deltoid The deltoid muscle is the only shoulder elevator if the supraspinatus is torn and dysfunctional. Anterior view of deltoid Posterior view of deltoid Free Body Diagram for calculating Deltoid Force In this diagram, with the arm fully extended the deltoid has to counteract the weight of the arm and a 25kg weight in the person's hand.

Moments pulling humerus down: 25 x 9. Moments puling humerus up: Deltoid d x sin10o x 0. Coronal Force Couple Deltoid and supraspinatus both contribute to abduction equally. Coraco-acromial Arch The coraco-acromial arch is the combination of the coracoid, coracoacromial ligament and acromion. Coraco-acromial arch green formed by the coracoid, coracoacromial ligament and acromion Long Head of Biceps The long head of biceps passes over the humeral head curving in two planes forming the shape of a question mark.

Rotator cuff patho-anatomy Cuff Ultrastructure The fusing of the rotatorcuff tendons suggests that they act more as a combined and integrative structure than as single entities.

The microstructure of the rotator cuff tendons near the insertions of the supraspinatus and infraspinatus has been further described as a five-layer structure: Layer one is composed of the superficial fibers of the coracohumeralligament. Layer two , which is the main portion of the cuff tendons, is seen as closely packed parallel tendon fibers grouped in large bundles extending directly from the muscle bellies to the insertion on the humerus. Layer three is also a thick tendinous structure but with smaller fascials than in layer two and a less uniform orientation.

Layer four is composed of loose connective tissues with thick bands of collagen fibers running perpendicular to the primary fiber orientation of the cuff tendons. This is Part I of a two-part article on clinical evaluation of the painful shoulder. Family physicians need to understand diagnostic and treatment strategies for common causes of shoulder pain.

We review key elements of the history and physical examination and describe maneuvers that can be used to reach an appropriate diagnosis. Examination of the shoulder should include inspection, palpation, evaluation of range of motion and provocative testing. In addition, a thorough sensorimotor examination of the upper extremity should be performed, and the neck and elbow should be evaluated.

Shoulder pain is a common complaint in family practice patients. The unique anatomy and range of motion of the glenohumeral joint can present a diagnostic challenge, but a proper clinical evaluation usually discloses the cause of the pain. The shoulder is composed of the humerus, glenoid, scapula, acromion, clavicle and surrounding soft tissue structures.

The shoulder region includes the glenohumeral joint, the acromioclavicular joint, the sternoclavicular joint and the scapulothoracic articulation Figure 1a. The glenohumeral joint capsule consists of a fibrous capsule, ligaments and the glenoid labrum. Because of its lack of bony stability, the glenohumeral joint is the most commonly dislocated major joint in the body. Glenohumeral stability is due to a combination of ligamentous and capsular constraints, surrounding musculature and the glenoid labrum.

Static joint stability is provided by the joint surfaces and the capsulolabral complex, and dynamic stability by the rotator cuff muscles and the scapular rotators trapezius, serratus anterior, rhomboids and levator scapulae. The rotator cuff is composed of four muscles: the supraspinatus, infraspinatus, teres minor and subscapularis Figure 1b. The subscapularis facilitates internal rotation, and the infraspinatus and teres minor muscles assist in external rotation.

The rotator cuff muscles depress the humeral head against the glenoid. With a poorly functioning torn rotator cuff, the humeral head can migrate upward within the joint because of an opposed action of the deltoid muscle. Scapular stability collectively involves the trapezius, serratus anterior and rhomboid muscles. The levator scapular and upper trapezius muscles support posture; the trapezius and the serratus anterior muscles help rotate the scapula upward, and the trapezius and the rhomboids aid scapular retraction.

A complete history begins with the patient's age, dominant hand and sport or work activity. It is important to assess whether the injury prevents or hampers normal work activities, hobbies and sports.

The patient should be asked about shoulder pain, instability, stiffness, locking, catching and swelling. Stiffness or loss of motion may be the major symptom in patients with adhesive capsulitis frozen shoulder , dislocation or glenohumeral joint arthritis.

Pain with throwing such as pitching a baseball suggests anterior glenohumeral instability. Patients who complain of generalized joint laxity often have multidirectional glenohumeral instability. Distinguishing between an acute and a chronic problem is diagnostically helpful Table 1. For example, a history of acute trauma to the shoulder with the arm abducted and externally rotated strongly suggests shoulder subluxation or dislocation and possible glenoid labral injury. In contrast, chronic pain and loss of passive range of motion suggest frozen shoulder or tears of the rotator cuff.

Shoulder pain in throwing athletes; anterior glenohumeral joint pain and impingement. Once the location, quality, radiation, and aggravating and relieving factors of the shoulder pain have been established, the possibility of referred pain should be excluded. Neck pain and pain that radiates below the elbow are often subtle signs of a cervical spine disorder that is mistaken for a shoulder problem.

The patient should be asked about paresthesias and muscle weakness. Pneumonia, cardiac ischemia and peptic ulcer disease can present with shoulder pain. A history of malignancy raises the possibility of metastatic disease. The patient should be asked about previous corticosteroid injections, particularly in the setting of osteopenia or rotator cuff tendon atrophy.

A complete physical examination includes inspection and palpation, assessment of range of motion and strength, and provocative shoulder testing for possible impingement syndrome and glenohumeral instability. The neck and the elbow should also be examined to exclude the possibility that the shoulder pain is referred from a pathologic condition in either of these regions.

The physical examination includes observing the way the patient moves and carries the shoulder. The patient should be properly disrobed to permit complete inspection of both shoulders. Swelling, asymmetry, muscle atrophy, scars, ecchymosis and any venous distention should be noted. Deformity, such as squaring of the shoulder that occurs with anterior dislocation, can immediately suggest a diagnosis.

Atrophy of the supraspinatus or infraspinatus should prompt a further work-up for such conditions as rotator cuff tear, suprascapular nerve entrapment or neuropathy. Palpation should include examination of the acromioclavicular and sternoclavicular joints, the cervical spine and the biceps tendon. The anterior glenohumeral joint, coracoid process, acromion and scapula should also be palpated for any tenderness and deformity.

Because the complex series of articulations of the shoulder allows a wide range of motion, the affected extremity should be compared with the unaffected side to determine the patient's normal range. Active and passive ranges should be assessed. For example, a patient with loss of active motion alone is more likely to have weakness of the affected muscles than joint disease.

Shoulder abduction involves the glenohumeral joint and the scapulothoracic articulation. Glenohumeral motion can be isolated by holding the patient's scapula with one hand while the patient abducts the arm. The first 20 to 30 degrees of abduction should not require scapulothoracic motion. With the arm internally rotated palm down , abduction continues to degrees. Beyond degrees, full abduction is possible only when the humerus is externally rotated palm up. The Apley scratch test is another useful maneuver to assess shoulder range of motion Figure 2.

In this test, abduction and external rotation are measured by having the patient reach behind the head and touch the superior aspect of the opposite scapula. Conversely, internal rotation and adduction of the shoulder are tested by having the patient reach behind the back and touch the inferior aspect of the opposite scapula. External rotation should be measured with the patient's arms at the side and elbows flexed to 90 degrees.

Apley scratch test. The patient attempts to touch the opposite scapula to test range of motion of the shoulder. Left Testing abduction and external rotation.

Right Testing adduction and internal rotation. In evaluating the rotator cuff, the patient's affected extremity should always be compared with the unaffected side to detect subtle differences in strength and motion. A key finding, particularly with rotator cuff problems, is pain accompanied by weakness.

True weakness should be distinguished from weakness that is due to pain. A patient with subacromial bursitis with a tear of the rotator cuff often has objective rotator cuff weakness caused by pain when the arm is positioned in the arc of impingement. Conversely, the patient will have normal strength if the arm is not tested in abduction.

The supraspinatus can be tested by having the patient abduct the shoulders to 90 degrees in forward flexion with the thumbs pointing downward. The patient then attempts to elevate the arms against examiner resistance Figure 3. The patient attempts to elevate the arms against resistance while the elbows are extended, the arms are abducted and the thumbs are pointing downward. Next, with the patient's arms at the sides, the patient flexes both elbows to 90 degrees while the examiner provides resistance against external rotation Figure 4.

This maneuver is used to evaluate the function of the infraspinatus and teres minor muscles, which are mainly responsible for external rotation. The patient attempts to externally rotate the arms against resistance while the arms are at the sides and the elbows are flexed to 90 degrees. Subscapularis function is assessed with the lift-off test. The patient rests the dorsum of the hand on the back in the lumbar area.

Inability to move the hand off the back by further internal rotation of the arm suggests injury to the subscapularis muscle. A modified version of the lift-off test is useful in a patient who cannot place the hand behind the back.

In this version, the patient places the hand of the affected arm on the abdomen and resists the examiner's attempts to externally rotate the arm.

Provocative tests provide a more focused evaluation for specific problems and are typically performed after the history and general examination have been completed Table 2. Neer's impingement sign is elicited when the patient's rotator cuff tendons are pinched under the coracoacromial arch. The test 4 is performed by placing the arm in forced flexion with the arm fully pronated Figure 5.