A positive Neer sign when elevating the shoulder above 120 degrees is characteristic in the impingement syndrome.

This process is commonly caused by a thickened tendon or an inflammation of the overlying bursa leading to an enlargement, thus compressing the subacromial space.Īnother possible cause for an impingement is a bony subacromial spur resulting in a narrowing of the nerve with pain. There the supraspinatus muscle tendon gets impinged at the acromion. Here are two examples:Īn example of a degenerative disease of the rotator cuff is the subacromial impingement syndrome. When looking at pathologies of the rotator cuff – as in all joints - one needs to differentiate between degenerative and traumatic lesions. The rotator cuff always pops up in exam questions! Make sure you're prepared for questions on its attachments, innervations and functions with our upper extremity muscle anatomy revision chart. In addition, the muscles tighten the joint capsule preventing a pinch during shoulder movements. The main function of the rotator cuff is to stabilize and center the humeral head in the joint socket, the glenoid cavity. The rotator cuff muscles are a favourite exam topic! Imprint them into your brain easily using the following mnemonic. It originates in the infraspinatous fossa of the scapula and inserts on the greater tubercle as well. The fourth muscle of the rotator cuff is the infraspinatus muscle. The s upraspinatus musclehas its origin in the supraspinatous fossa and inserts on the greater tubercle of the humerus – similar to the teres minor muscle. The teres minor muscleoriginates from the lateral border of the scapula and inserts on the greater tubercle of the humerus. The following article describes the anatomy, including the origins and insertions, together with the function and pathologies of the rotator cuff. Supraspinatus, Infraspinatus, Teres minor, Subscapularis) Innervation: upper and lower subscapular nerves (C5, C7)įunction: internal rotation of arm stabilization of humeral head in glenoid cavity. Insertion: lesser tubercle of the humerus Origin: medial two-third of the subscapular fossa Innervation: suprascapular nerve (C5, C6)įunction: external rotation of arm at glenohumeral joint stabilization of the humeral head in glenoid cavity.įunction: external rotation and adduction of arm at glenohumeral joint stabilization of the humeral head in glenoid cavity. Innervation: suprascapular nerve (C4, C6)įunction: initiation of abduction of arm to 15° at glenohumeral joint stabilization of humeral head in glenoid cavity. Injuries of the rotator cuff interfere with the function of the glenohumeral joint and correspond with inability to perform the movements associated with this joint. Its function is related to the glenohumeral joint, where the muscles of the cuff function both as the executors of the movements of the joint and the stabilization of the joint as well. Nearly 85 percent of the heat produced in the body is the result of muscle contraction.In the human body, the rotator cuff is a functional anatomical unit located in the upper extremity. Heat production, to maintain body temperature, is an important by-product of muscle metabolism. This is particularly evident in the knee and shoulder joints, where muscle tendons are a major factor in stabilizing the joint. The tendons of many muscles extend over joints and in this way contribute to joint stability. The skeletal muscles are continually making fine adjustments that hold the body in stationary positions. Posture, such as sitting and standing, is maintained as a result of muscle contraction. In addition to movement, muscle contraction also fulfills some other important functions in the body, such as posture, joint stability, and heat production. Skeletal muscles also produce more subtle movements that result in various facial expressions, eye movements, and respiration. The integrated action of joints, bones, and skeletal muscles produces obvious movements such as walking and running. Exceptions to this are the action of cilia, the flagellum on sperm cells, and amoeboid movement of some white blood cells. Nearly all movement in the body is the result of muscle contraction. Muscles, attached to bones or internal organs and blood vessels, are responsible for movement.

Their predominant function is contractibility. The muscular system is composed of specialized cells called muscle fibers. Acknowledgements Introduction to the Muscular System

Muscle actions