en Hand Surgery Hand Surgery Original Research Original Research <p> <strong> Abstract </strong></p><p> <strong> Background: </strong>The pathophysiology of carpal tunnel syndrome is associated with </p><p>  increased intracarpal canal pressure. Recently, palmaris longus has been introduced </p><p>  as an independent risk factor for the development of carpal tunnel syndrome. The </p><p>  purpose of this study was to assess the association of carpal tunnel syndrome with </p><p>  the presence of palmaris longus tendon and functional superficial flexor of the fifth </p><p>  finger. </p><p> <strong> Methods: </strong>Fifty-four patients with severe and bilateral carpal tunnel syndromes </p><p>  that had indications for carpal tunnel release, and underwent surgery, were enrolled </p><p>  prospectively in this study. Seventy patients as control group were selected on a basis </p><p>  of age, gender, occupation, diabetes mellitus, thyroid disease, and rheumatoid </p><p>  arthritis. The presence or absence of the palmaris longus tendon and functional superficial flexor tendon to the little finger were assessed in both groups clinically. </p><p> <strong> Results: </strong>The prevalence of palmaris longus agenesis was significantly lower in </p><p>  the carpal tunnel group but there was no association between carpal tunnel syndrome </p><p>  and presence of functional superficial flexor to the little finger. </p><p> <strong> Conclusion: </strong>The presence of the palmaris longus tendon is associated with the </p><p>  development of carpal tunnel syndrome. </p><p>  </p> carpal tunnel syndrome, palmaris longus, risk factor 8 11 http://mjiri.iums.ac.ir/browse.php?a_code=A-10-1-54&slc_lang=en&sid=1 Dawood Jafari 20031947532846001541 20031947532846001541 No Iran University of Medical Sciences, Tehran, Iran. Hamid Taheri 20031947532846001542 20031947532846001542 No Iran University of Medical Sciences, Tehran, Iran. Hooman Shariatzadeh 20031947532846001543 20031947532846001543 No Department of Hand Surgery, Shafa Yahyaiyan Rehabilitation Center, Farid Najd Mazhar najdmazhar@yahoo.ca 20031947532846001544 20031947532846001544 Yes Department of Hand Surgery, Shafa Yahyaiyan Rehabilitation Center, Marzieh Nojomi 20031947532846001545 20031947532846001545 No Iran University of Medical Sciences.