PRECISE LOCALIZATION OF THE MOTOR-NERVE BRANCHES TO THE HAMSTRING MUSCLES - AN AID TO THE CONDUCT OF NEUROLYTIC PROCEDURES

Objective: To identify the precise locations of the motor branches and motor points to the hamstring musculature and define these locations in relation to bony landmarks. Design: Descriptive study of adult cada ver limb dissection. The number, location, and course of the motor bra nches and motor points to each hamstring muscle from the sciatic nerve were defined relative to bony landmarks. Setting: Department of anato my at a university school of medicine. Participants: Anatomic dissecti on of 30 adult cadaver limbs (17 individuals) was completed. Adult cad avers were selected randomly without regard to gender, age, and race. Exclusion criteria included femoral fracture, surgery, inability to ob tain neutral position, and posterior thigh trauma. Main Outcome Measur e: A descriptive anatomic study based on linear measures in centimeter s from bony landmarks. Results: Two zones located along a line from th e ischial tuberosity to the lateral femoral condyle were observed to e xist. Zone one, containing the first motor branch to the biceps long h ead and semitendinosus, is found at approximately 20% (6.9 cm +/- 1.8 and 7.1 cm +/- 2.2 from the ischial tuberosity, respectively) of femur length along the stated line. Zone two, containing the primary branch to the semimembranosus and the secondary branches to the biceps and s emitendinosus, is found at approximately 33% (13.1 cm +/- 3.6, 12.6 cm +/- 3.9, and 14.3 cm +/- 3.9 from the ischial tuberosity, respectivel y) of femur length. Conclusions: The drawing of one surface line, when combined with our anthropometric observations, should increase the ea se and accuracy with which motor branch blocks to the hamstrings are p erformed. (C) 1996 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation