of the common flexor tendon . The development of this condition is accelerated if the client grips the smart phone harder than necessary , thereby increasing the contraction strength and therefore stress upon the musculature and its common tendon .
2 . Tennis Elbow
Tennis elbow , also known as lateral epicondylitis or lateral epicondylosis , is a condition in which inflammation and / or degeneration of the common extensor tendon occurs , usually accompanied by hypertonicity of the bellies of the associated muscles . This condition is caused by overuse of the muscles of the common extensor tendon that attaches to the lateral epicondyle of the humerus . These muscles are the extensor carpi radialis brevis , extensor digitorum , extensor digiti minimi , and the extensor carpi ulnaris . As a group , these muscles do extension of the wrist joint and the fingers . It would seem that these muscles do not need to contract when gripping and holding a smart phone because this activity requires contraction by flexion musculature , not extensor musculature . However , extensor musculature is needed to contract isometrically to stabilize the wrist joint and prevent it from flexing when the flexors digitorum superficialis and profundus muscles contract to flex the fingers . Most often , it is the extensor carpi radialis brevis that engages in this scenario ( Figure 2 ). Therefore , holding a smart phone does physically stress musculature of the common extensor tendon and can contribute to tennis elbow . Occasional use is not a problem ; like golfer ’ s elbow , tennis elbow is an overuse condition . Gripping the phone more forcefully than necessary will also increase the stress to the extensor musculature and therefore the likelihood that this condition will develop .
Figure 2 . Prolonged holding of a smart phone can lead to overuse , fatigue , and dysfunction of the common extensor tendon . This condition is known as tennis elbow .
Finger flexors
Figure 3 . Crimping a smart phone between the shoulder and ear physically stresses muscles of scapular elevation .
3 . Uptight Shoulders
Developing “ uptight ” elevated shoulders with a smart phone occurs when the phone is crimped ( compressed ) between the ear and shoulder , because this posture requires contraction of scapular elevation musculature to bring the shoulder up to hold the phone against the ear ( Figure 3 ). Muscles of scapular elevation that are used / overused and likely to become fatigued , tight , and injured are the upper trapezius and levator scapulae . Crimping a phone also requires contraction of sameside lateral flexion musculature of the neck to help press the ear downward against the phone and shoulder . This further requires contraction of , and therefore physically stresses , the upper trapezius and levator scapulae , as well as other muscles of lateral flexion . This problem is not new with smart phones . It was and still is common for people to crimp landline phones too . However , because smart phones are much smaller , the amount of muscular effort necessary to crimp a smart phone is greater than to crimp a landline phone .
4 . Anterior Shoulder Strain
It is common for people using a smart phone to hold the phone in the air out in front of their body . The difficulty with this posture is that it requires isometric contraction of the musculature of humeral flexion at the glenohumeral joint to hold the arm out in the air . Foremost among these muscles is the anterior deltoid ( Figure 4 ). Holding the arm out in flexion also requires stabilization of the scapula , which requires contraction of and therefore stress to the upper trapezius . And if the person also adds in elevation of the shoulder girdle to hold the phone up higher , it places even greater stress on the upper trapezius , as well as the levator scapulae . Therefore , excessive engagement of this posture can lead to anterior deltoid strain as well as strain of the upper trapezius and levator scapulae .
Figure 4 . Holding the phone out in front of the body can overly stress , fatigue , and injure musculature of the anterior shoulder
5 . Rotator Cuff Strain / Tendinitis
Holding a phone out in front of the body with humeral flexion can also stress and injure the rotator cuff musculature . Whenever the arm is lifted upward in the air , whether it is up into flexion , extension , abduction , or adduction , it is necessary for the rotator cuff musculature to contract to stabilize and hold the ( proximal ) head of the humerus down into the glenoid fossa as the distal end of the humerus raises ( Figure 5 ). Overuse of this posture can , over time , contribute to fatigue , tightening , and strain of the rotator cuff musculature , as well as tendinitis of the rotator cuff muscles .
Figure 5 . Holding the arm out in front of the body can also physically stress , fatigue , and injure musculature of the rotator cuff group .
ECRB
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