title: New insights into the function of the vastus medialis with clinical implications.
abstract: OBJECTIVE
  To investigate the gross anatomy of the distal portion of the quadriceps, and to compare the relative contributions of the vastus medialis oblique (VMO) and vastus lateralis (VL) during dynamic weight-bearing conditions.
  
  
  METHODS
  Dissection was carried out on 10 cadavers by a longitudinal incision from the anterior superior iliac spine to the patella and completed with upper and lower transverse cuts to reinvestigate the gross anatomy and innervation patterns of the quadriceps femoris. A biomechanical test of knee kinematics was conducted on 10 healthy male volunteers. Maximal isometric force, squat jump, and drop movement jump exercises were performed on a force plate and filmed using a Saga-3 3D system, and surface EMG activity was recorded for the VMO and the VL.
  
  
  RESULTS
  The oblique fibers of the vastus medialis (VM) are not only attached to the medial border of the patella, but they also have a small region of direct continuity with the patellar tendon. Furthermore, VMO fibers in the middle and proximal thirds of the thigh attached to vastus intermedius, whereas distally, the fibers were independent. Both parts of the VM (proximal and distal) had independent motor points. During jumping exercises, the VMO and VL were activated in a coordinated manner in a squat jump using both legs. However, in a single-leg squat jump (which challenged the stability of the knee joint more acutely), VMO activation was higher during landing.
  
  
  CONCLUSIONS
  VMO activity was pronounced during the weight-bearing conditions, with increased medial and lateral knee movements. This suggests that the VM should not be considered simply as a knee extensor or as a muscle whose main role is to maintain normal patellar tracking.
authors.affiliation: Cardiff School of Biosciences, University of Cardiff, Museum Avenue, Cardiff, United Kingdom. toumih@cardiff.ac.uk
authors.forename: Hechmi
authors.initials: H
authors.lastname: Toumi
authors.forename: Georges
authors.initials: G
authors.lastname: Poumarat
authors.forename: Mike
authors.initials: M
authors.lastname: Benjamin
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Best
authors.forename: Thomas
authors.initials: T
authors.lastname: Best
authors.forename: Slim
authors.initials: S
authors.lastname: F'Guyer
authors.forename: John
authors.initials: J
authors.lastname: Fairclough
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D004576:Electromyography; D005080:Exercise Test; D006801:Humans; D007717:Knee; D008297:Male; D052097:Quadriceps Muscle / Q000033:anatomy & histology*; D006113:United Kingdom; D016474:Weight-Bearing / Q000502:physiology*