title: Surgical anatomy of the lower trapezius tendon transfer.
abstract: BACKGROUND
  The precise surgical anatomy of the lower trapezius tendon transfer has not been well described. A precise anatomic description of the different trapezius segments and the associated neurovascular structures is crucial for operative planning and execution. We aimed (1) to establish a reliable demarcation between the middle and lower trapezius, (2) to establish the precise relationship of the main neurovascular pedicle to the muscle belly, and (3) to evaluate the utility of the relationships established in (1) and (2) by using the results of this study to perform cadaveric lower trapezius tendon harvest.
  
  
  METHODS
  In phase 1, a single surgeon performed all measurements using 10 cadavers. In phase 2, 10 cadaveric shoulders were used to harvest the tendon by using the relationships established in phase 1.
  
  
  RESULTS
  We found anatomically distinct insertion sites for the lower and middle trapezius. The lower trapezius inserted at the scapular spine dorsum and the middle trapezius inserted broadly along the superior surface of the scapular spine. The distance from tip of tendon insertion to the nearest nerve at the most superior portion of the lower trapezius was 58 mm (standard deviation ± 18). By use of these relationships, there were no cases of neurovascular injury during our cadaveric tendon harvests.
  
  
  CONCLUSIONS
  The lower trapezius can be reliably and consistently identified without violating fibers of the middle trapezius. Muscle splitting can be performed safely without encountering the spinal accessory nerve (approximately 2 cm medial to the medial scapular border).
authors.affiliation: Orthopaedic Surgery Department, University of Southern California Keck School of Medicine, Los Angeles, CA, USA. Electronic address: Omid@usc.edu.
authors.forename: Reza
authors.initials: R
authors.lastname: Omid
authors.affiliation: Orthopaedic Surgery Department, University of Southern California Keck School of Medicine, Los Angeles, CA, USA.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Cavallero
authors.affiliation: Orthopaedic Surgery Department, University of Southern California Keck School of Medicine, Los Angeles, CA, USA.
authors.forename: Danielle
authors.initials: D
authors.lastname: Granholm
authors.affiliation: Orthopaedic Surgery Department, University of Southern California Keck School of Medicine, Los Angeles, CA, USA.
authors.forename: Diego C
authors.initials: DC
authors.lastname: Villacis
authors.affiliation: Orthopaedic Surgery Department, University of Southern California Keck School of Medicine, Los Angeles, CA, USA.
authors.forename: Anthony M
authors.initials: AM
authors.lastname: Yi
mesh_terms: D000328:Adult; D002102:Cadaver; D004210:Dissection; D006801:Humans; D064171:Superficial Back Muscles / Q000033:anatomy & histology* / Q000098:blood supply / Q000294:innervation / Q000601:surgery*; D013709:Tendon Transfer; D013710:Tendons / Q000033:anatomy & histology / Q000601:surgery
keywords: Surgical anatomy; cadaveric study; lower trapezius; spinal accessory nerve; surgical landmarks; tendon transfer