Anatomical substract of the trapezius muscle myofascial trigger points

Abstract

Myofascial pain syndrome (MPS) is a common cause of chronic musculoskeletal pain and is characterized by myofascial trigger points(MTP), limited range of motion in joints, referred pain and local twitch response during mechanical stimulation of MTP. MTP are clinically identified by palpation of a taut band of muscle or fascia. Physiopathology of MPS remains unclear and it has been suggested that MTP occur when a nociceptor and a muscular motor endplate coincide. Seven different MTP are clinically described for the trapezius muscle, but anatomical correlation is still lacking. Trapezius muscles from two adult male cadavers were carefully dissected from their origins in order to observe the exact point where branches of the spinal accessory nerve entered the muscle belly. Four points were identified: (1) Mid portion of the superior margin, into the vertical fibers that reach the clavicle, (2) Caudal and lateral to the first point, located into the transverse fibers of the muscle; (3) Medial fibers near to the inferior margin of the muscle; (4) Central part of the muscle belly, between C7‐D3 levels. These locations correspond to the clinically described MTP. Anatomical correlation of the MTP may be useful for a better understanding of the physiopathology of these disorders and provide basis for their treatment.