Strict actions of the human wrist extensors: A study with an electrical neuromuscular stimulation method

Abstract

Motion and force produced by electrical neuromuscular stimulation (ENS) to each of the extensor carpi radialis longus (ECRL) and brevis (ECRB), and extensor carpi ulnaris (ECU) with the prone (P), semiprone (SP), and supine forearm (S) were studied in ten normal human subjects. Abduction (AB), extension (E), adduction (AD), and flexion (F) directions were represented by, respectively, 0°, 90°, 180°, and 270°. ENS to ECRL, ECRB, and ECU produced motion in direction of, respectively, 60° (mean), 87°, and 205° with P, 66°, 83°, and 166° with SP, and 47°, 66°, and 116° with S to maximal range. Direction/strength (Nm) of force by ENS to ECRL, ECRB, and ECU were, respectively, 54°/1.75, 74°/1.78, and 184°/1.49 with P, 34°/1.65, 63°/1.66, and 152°/1.43 with SP, and 32°/1.66, 70°/1.49, and 147°/1.25 with S. ENS to ECRL exhibited force of 15-20% of maximal E (15-20%Max-E) and 19-29%Max-AB, that to ECRB 24-32%Max-E, and that to ECU 17-30%Max-AD. The force study results suggest that ECRL is an abductor and extensor and ECRB is an extensor rather than an abductor. ECU should be an adductor rather than an extensor with SP and S and an adductor with P. The data must contribute to reconstruct motor functions of paralyzed hands.

Strict actions of the human wrist flexors: A study with an electrical neuromuscular stimulation method

“…Activities of FCR and FCU were studied in 10 healthy human subjects (6 males, 4 females, age range 21-45 years, right-handed) using the ENS method (Naito et al, 1994(Naito et al, , 2002Fujii et al, 2007;Sagae et al, 2010). All of the subjects gave their informed consent to the experimental procedure, which was approved by the Ethics Committee of Yamagata University School of Medicine, Yamagata, Japan.…”

“…The following three extensors and two flexors are chief actuators of the wrist: musculus (m.) extensor carpi radialis longus (ECRL), m. extensor carpi radialis brevis (ECRB), m. extensor ulnaris (ECU), m. flexsor carpi radialis (FCR), and m. flexor carpi ulnaris (FCU). We have been studying activities of muscles in living humans with an electrical neuromuscular stimulation (ENS) method (Naito et al, 1994(Naito et al, , 2002Fujii et al, 2007;Sagae et al, 2010). By using the ENS method, we studied strict actions of the wrist extensors (ECRL, ECRB, and ECU) in healthy human subjects (Sagae et al, 2010).…”

“…We have been studying activities of muscles in living humans with an electrical neuromuscular stimulation (ENS) method (Naito et al, 1994(Naito et al, , 2002Fujii et al, 2007;Sagae et al, 2010). By using the ENS method, we studied strict actions of the wrist extensors (ECRL, ECRB, and ECU) in healthy human subjects (Sagae et al, 2010). In our study, the direction and range of wrist-bending motion and the direction and strength of wrist-bending force produced by ENS to each of the extensors with the 90°pronated (prone), 0°pronated (semiprone), and 90°supinated (supine) forearm positions were measured.…”

Functional Significance of Facilitation Between the Pronator Teres and Extensor Carpi Radialis in Humans: Studies with Electromyography and Electrical Neuromuscular Stimulation

“…Lissajou's curves (trajectories in the coronary plane) was drawn with the data (x, y) using a 2-D Lissajou presentation program (RO299-4588G, Gigatex, Osaki, Japan). Video pictures and data of the 3DPS system were fed into a simultaneous recording system of digital video pictures and electric signals (The Teraview, Gigatex, Osaki, Japan) with EMGs (Sagae et al, 2010;Sato et al, 2007). During the movements, BB showed activities increasing and decreasing and PT, ECRL, and ECRB parallel activities decreasing and increasing at the supination and pronation phases, respectively, in all the five subjects (Fig.…”

“…The forearm was put on an experimental table in the prone, semiprone, and supine positions. For electrical stimulation, monopolar electrodes made of teflon-coated stainless steel wire (above-mentioned product) were implanted percutaneously into each motor point of ECRL and PT with 27 gauge injectionneedles Naito et al, 1994Naito et al, , 2002Sagae et al, 2010). A guide needle of a 25 gauge spinal-needle (length: 89 mm, Top Co., Tokyo, Japan) was percutaneously inserted into the subcutaneous tissue along to the lateral intermuscular septum of the arm and used as reference.…”