title: Humeral insertion of the supraspinatus and infraspinatus. New anatomical findings regarding the footprint of the rotator cuff. Surgical technique.
abstract: BACKGROUND
  It is generally believed that the supraspinatus is the most commonly involved tendon in rotator cuff tears. Clinically, however, atrophy of the infraspinatus muscle is frequently observed in patients with even small to medium-size rotator cuff tears. This fact cannot be fully explained by our current understanding of the anatomical insertions of the supraspinatus and infraspinatus. The purpose of this study was to reinvestigate the humeral insertions of these tendons.
  
  
  METHODS
  The study included 113 shoulders from sixty-four cadavers. The humeral insertion areas of the supraspinatus and infraspinatus were investigated in ninety-seven specimens. In sixteen specimens, all muscular portions of the supraspinatus and infraspinatus were removed, leaving the tendinous portions intact, in order to define the specific characteristics of the tendinous portion of the muscles. Another twenty-six shoulders were used to obtain precise measurements of the footprints of the supraspinatus and infraspinatus.
  
  
  RESULTS
  The supraspinatus had a long tendinous portion in the anterior half of the muscle, which always inserted into the anteriormost area of the highest impression on the greater tuberosity and which inserted into the superiormost area of the lesser tuberosity in 21% of the specimens. The footprint of the supraspinatus was triangular in shape, with an average maximum medial-to-lateral length of 6.9 mm and an average maximum anteroposterior width of 12.6 mm. The infraspinatus had a long tendinous portion in the superior half of the muscle, which curved anteriorly and extended to the anterolateral area of the highest impression of the greater tuberosity. The footprint of the infraspinatus was trapezoidal in shape, with an average maximum medial-to-lateral length of 10.2 mm and an average maximum anteroposterior width of 32.7 mm.
  
  
  CONCLUSIONS
  The footprint of the supraspinatus on the greater tuberosity is much smaller than previously believed, and this area of the greater tuberosity is actually occupied by a substantial amount of the infraspinatus.
authors.affiliation: Unit of Clinical Anatomy, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan. mochizuki.orj@tmd.ac.jp
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Mochizuki
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Sugaya
authors.forename: Mari
authors.initials: M
authors.lastname: Uomizu
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Maeda
authors.forename: Keisuke
authors.initials: K
authors.lastname: Matsuki
authors.forename: Ichiro
authors.initials: I
authors.lastname: Sekiya
authors.forename: Takeshi
authors.initials: T
authors.lastname: Muneta
authors.forename: Keiichi
authors.initials: K
authors.lastname: Akita
mesh_terms: D002102:Cadaver; D006801:Humans; D006811:Humerus / Q000033:anatomy & histology*; D019637:Orthopedic Procedures / Q000379:methods*; D017006:Rotator Cuff / Q000033:anatomy & histology* / Q000601:surgery; D000070636:Rotator Cuff Injuries; D012785:Shoulder Joint / Q000033:anatomy & histology*; D013708:Tendon Injuries / Q000473:pathology / Q000601:surgery