title: Trigger points: an anatomical substratum.
abstract: This study aimed to bring the trapezius muscle knowledge of the locations where the accessory nerve branches enter the muscle belly to reach the motor endplates and find myofascial trigger points (MTrPs). Although anatomoclinical correlations represent a major feature of MTrP, no previous reports describing the distribution of the accessory nerve branches and their anatomical relationship with MTrP are found in the literature. Both trapezius muscles from twelve adult cadavers were carefully dissected by the authors (anatomy professors and medical graduate students) to observe the exact point where the branches of the spinal accessory nerve entered the muscle belly. Dissection was performed through stratigraphic layers to preserve the motor innervation of the trapezius muscle, which is located deep in the muscle. Seven points are described, four of which are motor points: in all cases, these locations corresponded to clinically described MTrPs. The four points were common in these twelve cadavers. This type of clinical correlation between spinal accessory nerve branching and MTrP is useful to achieve a better understanding of the anatomical correlation of MTrP and the physiopathology of these disorders and may provide a scientific basis for their treatment, rendering useful additional information to therapists to achieve better diagnoses and improve therapeutic approaches.
authors: Department of Surgery, Laboratory of Medical Research, Division of Human Structural Topography, Faculty of Medicine of the University of São Paulo (FMUSP), 04717-003 São Paulo, SP, Brazil.
authors: Flávia Emi
authors: FE
authors: Akamatsu
authors: Postgraduate Program of the Surgical Clinic of FMUSP, 01246-903 São Paulo, SP, Brazil.
authors: Bernardo Rodrigues
authors: BR
authors: Ayres
authors: Postgraduate Program of the Surgical Clinic of FMUSP, 01246-903 São Paulo, SP, Brazil.
authors: Samir Omar
authors: SO
authors: Saleh
authors: Department of Surgery Medicine, Laboratory of Medical Research, FMUSP, 01246-903 São Paulo, SP, Brazil.
authors: Flávio
authors: F
authors: Hojaij
authors: Department of Surgery, Laboratory of Medical Research, Division of Human Structural Topography, Faculty of Medicine of the University of São Paulo (FMUSP), 04717-003 São Paulo, SP, Brazil.
authors: Mauro
authors: M
authors: Andrade
authors: Department of Pathology, Discipline of Telemedicine, FMUSP, 01246-903 São Paulo, SP, Brazil.
authors: Wu Tu
authors: WT
authors: Hsing
authors: Department of Surgery, Laboratory of Medical Research, Division of Human Structural Topography, Faculty of Medicine of the University of São Paulo (FMUSP), 04717-003 São Paulo, SP, Brazil.
authors: Alfredo Luiz
authors: AL
authors: Jacomo
mesh_terms: D000328:Adult; D002102:Cadaver; D005260:Female; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000033:anatomy & histology* / Q000294:innervation; D061028:Trigger Points / Q000033:anatomy & histology*