title: Quantitative Anatomy of the Trapezius Muscle in the Human Fetus.
abstract: BACKGROUND
  The trapezius muscle consists of three parts that are capable of functioning independently. Its superior part together with the levator scapulae and rhomboids elevate the shoulder, the middle part retracts the scapula, while the inferior part lowers the shoulder.
  
  
  OBJECTIVE
  The present study aimed to supplement numerical data and to provide growth dynamics of the trapezius in the human fetus.
  
  
  METHODS
  Using methods of anatomical dissection, digital image analysis (NIS Elements AR 3.0), and statistics (Student's t-test, regression analysis), we measured the length, the width and the surface area of the trapezius in 30 fetuses of both sexes (13 k,17  ) aged 13-19 weeks.
  
  
  RESULTS
  Neither sex nor laterality differences were found. All the studied parameters of the trapezius increased proportionately with age. The linear functions were computed as follows: y = -103.288 + 10.514 × age (r = 0.957) for total length of the trapezius muscle, y = -67.439 + 6.689 × age (r = 0.856) for length of its descending part, y = -8.493 + 1.033 × age (r = 0.53) for length of its transverse part, y = -27.545 + 2.802 × age (r = 0.791) for length of its ascending part, y = -19.970 + 2.505 × age (r = 0.875) for width of the trapezius muscle, and y = -2670.458 + 212.029 × age (r = 0.915) for its surface area.
  
  
  CONCLUSIONS
  Neither sex nor laterality differences exist in the numerical data of the trapezius muscle in the human fetus. The descending part of trapezius is the longest, while its transverse part is the shortest. The growth dynamics of the fetal trapezius muscle follows proportionately.
authors.affiliation: Department of Normal Anatomy, The Ludwik Rydygier Collegium Medicum in Bydgoszcz, The Nicolaus Copernicus University in Toruń, Poland.
authors.forename: Mateusz
authors.initials: M
authors.lastname: Badura
authors.affiliation: Department of Normal Anatomy, The Ludwik Rydygier Collegium Medicum in Bydgoszcz, The Nicolaus Copernicus University in Toruń, Poland.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Grzonkowska
authors.affiliation: Department of Normal Anatomy, The Ludwik Rydygier Collegium Medicum in Bydgoszcz, The Nicolaus Copernicus University in Toruń, Poland.
authors.forename: Mariusz
authors.initials: M
authors.lastname: Baumgart
authors.affiliation: Department of Normal Anatomy, The Ludwik Rydygier Collegium Medicum in Bydgoszcz, The Nicolaus Copernicus University in Toruń, Poland.
authors.forename: Michał
authors.initials: M
authors.lastname: Szpinda
mesh_terms: D005260:Female; D005333:Fetus / Q000033:anatomy & histology*; D006801:Humans; D008297:Male; D064171:Superficial Back Muscles / Q000196:embryology* / Q000254:growth & development*
keywords: human fetuses; length; surface area; trapezius muscle; width