title: The twisted structure of the human Achilles tendon.
abstract: The Achilles tendon (AT) consists of fascicles that originate from the medial head of the gastrocnemius (MG), lateral head of the gastrocnemius (LG), and soleus muscle (Sol). These fascicles are reported to have a twisted structure. However, there is no consensus as to the degree of torsion. The purpose of this study was to investigate the twisted structure of the AT at the level of fascicles that originate from the MG, LG, and Sol, and elucidate the morphological characteristics. Gross anatomical study of 60 Japanese cadavers (111 legs) was used. The AT fascicles originated from the MG, LG, and Sol were fused while twisting among themselves. There were three classification types depending on the degree of torsion. Further fine separation of each fascicle revealed MG ran fairly parallel in all types, whereas LG and Sol, particularly of the extreme type, were inserted onto the calcaneal tuberosity with strong torsion. In addition, the sites of Sol torsion were 3-5 cm proximal to the calcaneal insertion of the AT. These findings provide promising basic data to elucidate the functional role of the twisted structure and mechanisms for the occurrence of AT injury and other conditions.
authors.affiliation: Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, Niigata, Japan.|Department of Anatomy, School of Life Dentistry at Niigata, Nippon Dental University, Niigata, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Edama
authors.affiliation: Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, Niigata, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Kubo
authors.affiliation: Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, Niigata, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Onishi
authors.affiliation: Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, Niigata, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Takabayashi
authors.affiliation: Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, Niigata, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Inai
authors.affiliation: Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, Niigata, Japan.
authors.forename: E
authors.initials: E
authors.lastname: Yokoyama
authors.affiliation: Department of Rehabilitation, Sanjo General Hospital, Niigata, Japan.
authors.forename: W
authors.initials: W
authors.lastname: Hiroshi
authors.affiliation: Department of Rehabilitation, Niigata Medical Center, Niigata, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Satoshi
authors.affiliation: Department of Anatomy, School of Life Dentistry at Niigata, Nippon Dental University, Niigata, Japan.
authors.forename: I
authors.initials: I
authors.lastname: Kageyama
mesh_terms: D000125:Achilles Tendon / Q000033:anatomy & histology*; D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D002102:Cadaver; D004210:Dissection; D005260:Female; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000033:anatomy & histology; D012737:Sex Factors; D054159:Torsion, Mechanical
keywords: Achilles tendinopathy; Japanese cadavers; gastrocnemius; soleus