Extensor pollicis brevis
Abductor pollicis longus
Figure 8 . Texting thumb often involves overuse and injury to the tendons of the abductor pollicis longus and extensor pollicis brevis .
10 . Texting Thumb
Texting thumb is the name given to irritation / inflammation / injury to the tendons of the thumb due to repetitive overuse when texting or otherwise using a smart phone . The strain to the thumb comes less from the pressing of the thumb against the phone that it does from the traveling of the thumb that is necessary to move from one area of the screen to another ; although pressing harder would add to the physical stress . The muscles of the thumb can be divided into intrinsic and extrinsic groups . Intrinsic thumb muscles are wholly located within the hand ; in other words they originate within the hand and insert onto the thumb . Extrinsic thumb muscles have their proximal attachment ( origin ) in the arm or forearm and then attach onto the thumb . The intrinsic thumb muscles are the abductor pollicis brevis , flexor pollicis brevis , opponens pollicis ( all of the thenar group ), and the adductor pollicis . The extrinsic muscles are the flexor pollicis longus , abductor pollicis longus , extensor pollicis brevis , and extensor pollicis longus .
Although the tendons of any of the muscles of the thumb can be involved , the tendons , or more precisely the synovial sheathes of the tendons , of the abductor pollicis longus and extensor pollicis brevis are most commonly involved because the use of these muscles causes their tendons to rub against the styloid process of the radius ( Figure 8 ). Tenosynovitis of these tendons is also known as de Quervain ’ s disease ( or de Quervain ’ s stenosing tenosynovitis ).
Suggested Smart Phone Postures
Following are a few tips for posture when using a smart phone . Certainly , any static posture that is assumed for prolonged periods of time , even an ideal posture , can result in stiffness and excessive stress to the body . For this reason , it is wise to take a break from your smart phone every few minutes so that you can move and change your posture .
Tips for smart phone posture :
1 . Try to work with the phone at , or as close to eye level as possible ; but it is important for your arm ( s ) to be supported ( Figure 9A ).
2 . If present , perhaps you can lean your elbows on an armrest to support your arms . This might not quite bring the phone to eye level , but it will allow both hands to be free when writing / typing ( Figure 9B ).
3 . Alternately , one elbow can be supported on an armrest with the other arm supported by your trunk . This will allow the phone to be held slightly higher and closer to eye level , but may cause you to lean your trunk toward the side of the armrest ( Figure 9C ).
4 . If no armrest is present , then try to support your arms against your trunk ( Figure 9D ). This might slightly round the shoulders , but it does support the arms and it brings the phone up higher .
5 . If one forearm can be held across your abdomen , then the other elbow can rest on it and this will bring the smart phone even higher and up to eye level . This is the best posture for your upper body . But because only one hand is free , this posture might not be best when typing but is recommended when reading ( see Figure 9A ).
6 . Alternately , your elbows can be supported on your knees ( Figures 9D and E ). 7 . Hold the phone gently . 8 . When typing , tap the phone lightly .
A
C
E
Figure 9 . Suggested postures for smart phone use
Dr Joe Muscolino has been a manual and movement therapy educator for more than 35 years . He is the author of extensive online streaming video content on anatomy , physiology , and kinesiology , as well as assessment and treatment skillsets for manual therapists and movement professionals . He has created Learn Muscles Continuing Education ( LMCE ), with over 2,800 video lessons , with new video lessons added every week . He has also created Master Classes in Muscle Anatomy ( MAMC ), Bone and Joint Anatomy ( BAJAMC ), Kinesiology ( KMC ), and Visceral Anatomy ( VAMC ). And he has created an Anatomy Master Class Curriculum for massage and other manual and movement therapy educational institutions . He is the author of multiple textbooks , including The Muscular System Manual : The Skeletal Muscles of the Human Body ( Elsevier , 2017 ); The Muscle and Bone Palpation Manual with Trigger Points , Referral Patterns , and Stretching ( Elsevier , 2016 ); and Kinesiology : The Skeletal System and Muscle Function ( Elsevier , 2017 ). And he teaches continuing education workshops around the world , including a certification in Clinical Orthopedic Manual Therapy ( COMT ). Visit www . learnmuscles . com for more information , or you can reach him directly at joseph . e . muscolino @ gmail . com .
B
D
F
80 | vol29 | no2 | JATMS