Localization of Motor Points in the Anterior Thigh Muscles Motor Points of Quadriceps

Abstract

Background: No previous information of the motor point location reported as an x, y coordination of the anterior thigh muscles in Thai people has been reported.

Objective: To evaluate the location and the distribution of the motor point (MP) of vastus lateralis (VL), rectus femoris (RF), and vastus medialis (VM) using an x, y coordination.

Methods: A cross-sectional study was applied. Thirty healthy 18-35 years old were volunteered. The thigh length (Y) was measured from the anterior superior iliac spine (ASIS) to the patella. The coordinate x is the perpendicular distance from the Y-axis. The negative x-value means that the MP is on the lateral side of the Y-line. The coordinate y is the distance along the Y-axis. The x, y values are calculated as a percentage of Y. The MP location was determined with a small point electrode using a 1-Hz monophasic pulsed current, pulse duration of 0.1 ms.

Results: MP position reported as x, y value of VL is -10.92, 68.72%Y, RF is 2.03, 53.26%Y and VM is 14.68, 82.19%Y. The VL showed the highest distribution of MP locations, determined by the standard deviation, of 6.55%Y, or a difference of 2.4-3.3 cm from the mean value, depending on the thigh length. This discrepancy may be compensated if large stimulation electrodes are used. 

Conclusion: Although the correct MP location must be obtained from an individual patient. The present data may be clinically useful because it reduces the time and extent of the area for locating the MP locations.