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.

Anatomical versus functional motor points of selected upper body muscles

“…In fact, only the BB showed a strong interindividual heterogeneity with regard to the innervation points of the MCN in the BDs. In comparing the current findings with previous findings from other research groups, strong agreements for location and quantity of NEPs could be seen for BB, Pmin, and TZ . However, due to varying reference lengths and different anatomical landmarks, direct comparisons between studies should be viewed with caution …”

“…Similarly, the positioning of lidocaine injections (e.g., in chronic neck pain) based on anatomical myofascial trigger points (MTrPS) may be optimized by identifying high‐density IZs . Typically used MTrPS appear to be largely in line with NEPs rather than MPs. The differences between NEPs and MPs was shown in a study by Barbero and colleagues, who reported that, in the trapezius muscle, MTrPS and IZ did not overlap.…”

“…In comparing the current findings with previous findings from other research groups, strong agreements for location and quantity of NEPs could be seen for BB, 22 Pmin, 23 and TZ. 6,24 However, due to varying reference lengths and different anatomical landmarks, direct comparisons between studies should be viewed with caution. 3,5,25,26 Comparing these anatomical findings with our previous study in which MPs were defined by NMES, we were able to illustrate substantial differences in the locations of NEPs obtained by anatomic dissection, as compared with MPs determined by NMES.…”

An Anatomical Basis for the Myofascial Trigger Points of the Abductor Hallucis Muscle

“…e relationship between the entry points of nerves into the muscle belly and the myofascial trigger points has already been reported by Akamatsu et al [25,26]. Nerves are responsible for muscle contraction through the release of acetylcholine from the motor endplate.…”

“…Another important finding described in a recent study demonstrated that there may be a relationship between the entry points of the nerves to the muscle belly and the myofascial trigger points [25,26]. A detailed description of the anatomy remains one of the best ways to better understand the pathophysiology and clinical applicability of myofascial trigger points.…”