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Evaluation and Treatment of the Shoulder Complex: Summary
Lateral Muscular Anatomy of the Shoulder Complex
Proximal Attachment
Distal Attachment
Muscle
Function
Dysfunction
Superior translation of humerus on scapula, which leads to subacromial impingement
Deltoid (anterior, posterior and middle fibers)
Spine of scapula (posterior fibers), acromion process (middle fibers), and lateral third of clavicle (anterior fibers)
Deltoid tuberosity
Shoulder flexion/ IR (anterior fibers); shoulder abduction (all fibers); shoulder extension/external rotations (posterior fibers)
Posterior Muscular Anatomy of Shoulder Complex
Proximal Attachment
Distal Attachment Intertubercular groove of humerus
Muscle
Function
Dysfunction
Latissimus dorsi
Spinous process T7– T12, thoracolumbar fascia, inferior angle of scapula, and iliac crest
Shoulder extension, adduction, and IR
Limited shoulder flexion
Pectoralis minor (deep muscle)
Ribs 3–5
Coracoid process of scapula
Anterior tilt of scapula; protraction of scapula
Anterior tilt of scapula and
restricted range of motion in all planes at shoulder Anterior tilt of the scapula; humeral IR as a result of shortening of the short head; limited shoulder extension and ER
Biceps brachii (superficial muscle)
Short head–coracoid process; long head– supraglenoid tubercle
Radial tuberosity
Shoulder flexion and IR; elbow
flexion and supination
Coracobrachialis Coracoid process
Midshaft of humeral
Shoulder flexion; shoulder IR
Anterior tilt of scapula; protraction of scapula
The posterior fascia is composed of three layers, as opposed to other areas of fascia, which are typically composed of two layers. The posterior fascia associated with the shoulder complex encapsulates the scapula, erector spinae, and latissimus dorsi, which are also all components that help create the posterior functional line (image B). The portion of the posterior fascia known as the thoracolumbar fascia can thicken over time with chronic pain.
Subsequently, this thickening results in additional pressure on encapsulated nerves. These nerve types include nociceptors, which are responsible for pain; proprioceptors, which are responsible for postural changes; and mechanoreceptors, which can cause altered recruitment patterns with encapsulation. In all, it is important to note and assess for instability of the lumber spine, as this can result in abnormal movements of the shoulder complex.
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