Movements
The glenoid fossa is shallow and contains the glenoid labrum which deepens it and aids in stability. With 120 degrees of unassisted flexion, the glenohumeral joint is the most mobile joint in the body.
Scapulohumeral rhythm helps to achieve further range of movement. The Scapulohumeral rhythm is the movement of the scapula across the thoracic cage in relation to the humerus. This movement can be compromised by anything that changes the position of the scapula. This could be an imbalance in the muscles that hold the scapula in place which are the upper and lower trapezium. This imbalance could cause a forward head carriage which in turn can affect the range of movements of the shoulder.
The rotator cuff muscles of the shoulder produce a high tensile force, and help to pull the head of the humerus into the glenoid fossa.
| Movement | Muscles | Origin | Insertion |
|---|---|---|---|
| Flexion (150°–170°) |
Anterior fibers of deltoid | Clavicle | Middle of lateral surface of shaft of humerus |
| Clavicular part of pectoralis major | Clavicle | Lateral lip of bicipital groove of humerus | |
| Long head of biceps brachii | Supraglenoid tubercle of scapula | Tuberosity of radius, Deep fascia of forearm | |
| Short head of biceps brachii | Coracoid process of scapula | ||
| Coracobrachialis | Coracoid process | Medial aspect of shaft of humerus | |
| Extension (40°) |
Posterior fibers of deltoid | Spine of scapula | Middle of lateral surface of shaft of humerus |
| Latissimus dorsi | Iliac crest, lumbar fascia, spines of lower six thoracic vertebrae, lower 3–4 ribs, inferior angle of scapula | Floor of bicipital groove of humerus | |
| Teres major | Lateral border of scapula | Medial lip of bicipital groove of humerus | |
| Abduction (160°–180°) |
Middle fibers of deltoid | Acromion process of scapula | Middle of lateral surface of shaft of humerus |
| Supraspinatus | Supraspinous fossa of scapula | Greater tuberosity of humerus | |
| Adduction (30°–40°) |
Sternal part of pectoralis major | Sternum, upper six costal cartilages | Lateral lip of bicipital groove of humerus |
| Latissimus dorsi | Iliac crest, lumbar fascia, spines of lower six thoracic vertebrae, lower 3-4 ribs, inferior angle of scapula | Floor of bicipital groove of humerus | |
| Teres major | Lower third of lateral border of scapula | Medial lip of bicipital groove of humerus | |
| Teres minor | Upper two thirds of lateral border of scapula | Greater tuberosity of humerus | |
| Lateral rotation (in abduction: 95°; in adduction: 70°) |
Infraspinatus | Infraspinous fossa of scapula | Greater tuberosity of humerus |
| Teres minor | Upper two thirds of lateral border of scapula | Greater tuberosity of humerus | |
| Posterior fibers of deltoid | Spine of scapula | Middle of lateral surface of shaft of humerus | |
| Medial rotation (in abduction: 40°–50°; in adduction: 70°) |
Subscapularis | Subscapular fossa | Lesser tuberosity of humerus |
| Latissimus dorsi | Iliac crest, lumbar fascia, spines of lower 3-4 ribs, inferior angle of scapula | Floor of bicipital groove of humerus | |
| Teres major | Lower third of lateral border of scapula | Medial lip of bicipital groove of humerus | |
| Anterior fibers of deltoid | Clavicle | Middle of lateral surface of shaft of humerus |
Read more about this topic: Glenohumeral Joint
Famous quotes containing the word movements:
“The novel is not “a crazy quilt of bits”; it is a logical sequence of psychological events: the movements of stars may seem crazy to the simpleton, but wise men know the comets come back.”
—Vladimir Nabokov (1899–1977)
“In a universe that is all gradations of matter, from gross to fine to finer, so that we end up with everything we are composed of in a lattice, a grid, a mesh, a mist, where particles or movements so small we cannot observe them are held in a strict and accurate web, that is nevertheless nonexistent to the eyes we use for ordinary living—in this system of fine and finer, where then is the substance of a thought?”
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“Awareness of the stars and their light pervades the Koran, which reflects the brightness of the heavenly bodies in many verses. The blossoming of mathematics and astronomy was a natural consequence of this awareness. Understanding the cosmos and the movements of the stars means understanding the marvels created by Allah. There would be no persecuted Galileo in Islam, because Islam, unlike Christianity, did not force people to believe in a “fixed” heaven.”
—Fatima Mernissi, Moroccan sociologist. Islam and Democracy, ch. 9, Addison-Wesley Publishing Co. (Trans. 1992)