title: Determination of normative neck muscle morphometry using upright MRI with comparison to supine data.
abstract: BACKGROUND
  Neck muscles are important in the static and dynamic stability of the head-neck complex. Deep neck muscles act to maintain upright posture and superficial muscles are responsible for gross movements. Previous studies have quantified neck muscle geometry using traditional supine magnetic resonance imaging (MRI). However, supine orientation removes the vertical load on the cervical spine from the head-neck complex and changes the relative orientation of the spine and neck muscles. Therefore, the purpose of this study was to demonstrate the feasibility of upright MRI to obtain neck muscle morphometric data on a spinal level-by-level basis for subjects in upright seated positions.
  
  
  METHODS
  Upright MRI scans were obtained of the neck region for six younger male volunteers in neutral and flexed positions. Planar images were oriented parallel to the intervertebral disc space at each level. Cross-sectional area (CSA) and orientation of neck muscles were quantified at four spinal levels.
  
  
  RESULTS
  Area and position of all four muscles were significantly dependent upon spinal level. Average CSA of the sternocleidomastoid, longus colli, levator scapulae, and trapezius muscles in neutral position were 512, 113, 281, and 174 mm2. Head-neck position significantly affected area and position of the sternocleidomastoid and position of posterior neck muscles.
  
  
  CONCLUSIONS
  Comparison of neck muscle areas from the present study to a previous study incorporating supine MRI demonstrated differing trends between anterior and posterior neck muscles that may be attributable to upright orientation of volunteers and planar image orientation in the present study. Differences between supine and upright MRI identified in the present study may warrant incorporation of this technique in future spinal imaging studies.
authors.affiliation: Medical College of Wisconsin, 5000 West National Ave., Research 151, Milwaukee, WI 53295, USA. bstemper@mcw.edu
authors.forename: Brian D
authors.initials: BD
authors.lastname: Stemper
authors.forename: Jamie L
authors.initials: JL
authors.lastname: Baisden
authors.forename: Narayan
authors.initials: N
authors.lastname: Yoganandan
authors.forename: Frank A
authors.initials: FA
authors.lastname: Pintar
authors.forename: Glenn R
authors.initials: GR
authors.lastname: Paskoff
authors.forename: Barry S
authors.initials: BS
authors.lastname: Shender
mesh_terms: D000328:Adult; D000886:Anthropometry / Q000379:methods*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009334:Neck Muscles / Q000033:anatomy & histology*; D016684:Prone Position; D012016:Reference Values; D016683:Supine Position