Vastus medialis: anatomical and functional considerations and implications based upon human and cadaveric studies.

OBJECTIVE: To provide an electrophysiological and functional description of the vastus medialis (VM) and contrast it to an anatomical description. METHODS: Motor points of all superficial portions of the quadriceps were identified on the dominant side of 8 human subjects and electrically stimulated to achieve a light contraction to trace and measure the orientation of the fibers. Electromyography of the VM was then recorded over 2 motor points during isometric and isokinetic maximum knee extensions. An independent laboratory dissected 39 cadaveric specimens focusing on fiber orientations and distal insertions of the VM. RESULTS: Results revealed 5 motor points for the quadriceps: 1 point for the vastus lateralis, 1 point for the rectus femoris (RF), and 3 points for the VM. The 3 VM motor points suggest 3 separate groups of fibers: proximal (pf), median (mf), distal (df). Fiber orientations ranged from 45 degrees for VMpfs to 55 degrees for VMdfs. Motor point stimulation and anatomical dissection clearly showed that the VMpfs and VMmfs were inserted on a tendon common to the RF, whereas VMdfs were attached directly to the medial aspect of the patella. Furthermore, the VMpfs were more active (P < .05) than VMdfs during maximum knee extensions. CONCLUSION: The anatomy, motor points, and electromyography clearly support an important distinction between the VMpfs and VMdfs. The role of the VMpfs would be one of assisting the RF in knee extension, whereas the VMdfs would track the patella medially without participating in knee extension. Because of these anatomical and functional differences, the VMpfs and VMdfs should be addressed very differently during quadriceps rehabilitation in patellofemoral dysfunctions.

[Compression of the bulbar urethra by transobturator suburethral tape: anatomical study]. / Compression de l'urèthre bulbaire par bandelette sous uréthrale trans-obturatrice: étude anatomique.

INTRODUCTION: The management of female stress urinary incontinence has been markedly improved by the suprapubic tension-free vaginal tape (TVT) and transobturator tape techniques. The objective of our study was to assess the feasibility of this type of technique in males based on cadavre dissection. MATERIAL AND METHOD: A 300 mm x 15 mm polypropylene tape was inserted via a transobturator approach on a cadavre stored in the refrigerator at 4 degrees C and on three cadavres stored in formalin. The technique was almost identical to that used in females. It requires a midline perineal incision in the raphe and two small lateral incisions. The deep transverse muscle of the perineum was opened with scissors. The needle was introduced via the lateral incisions and its progression was guided by a finger introduced into the perineal orifice. The cadavre was then sectioned sagittally to verify the course of the tape and its relations to adjacent structures. RESULTS: The operative technique did not raise any particular problems. Dissection revealed that the tape crossed the deep transverse muscle of the perineum and the levator ani muscle, before travelling towards the obturator foramen. The tape avoided the bladder, prostate, corpora cavernosa, and pudendal pedicle. CONCLUSION: The transobturator tape technique therefore appears to be feasible in males. It does not appear to comprise any particular risks for adjacent organs. This anatomical study appeared to be essential before considering an in vivo application.