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

Abstract

Myofascial pain syndrome is characterized by pain and a limited range of joint motion caused by muscle contracture related to motor-end-plate dysfunction and the presence of myofascial trigger points (MTrPs). It is the most frequent cause of musculoskeletal pain, with a worldwide prevalence varying between 13.7% and 47%. Of the patients with myofascial pain syndrome, approximately 17% have pain in the medial hindfoot area. The abductor hallucis muscle is located in the medial, posterior region of the foot and is related to painful plantar syndromes. The objective of this study was to describe the distribution of the medial plantar nerve and their anatomical relationship with MTrPs found in the literature. Thirty abductor hallucis muscles were dissected from 15 human cadavers (8 males and 7 females). The muscles were measured, and the distribution data of the medial plantar nerve branches in each quadrant were recorded. For statistical analysis, we used generalized estimation equations with a Poisson distribution and a log logarithm function followed by Bonferroni multiple comparisons of the means. The data are expressed as the mean ± standard deviation. The level of significance was adjusted to 5% (p<0.05). A high concentration of nerve branches was observed in the first quadrant (Q1) of the abductor hallucis muscle, which is the same area in which the MTrPs are described. The topography of the entry points of the branches of the medial plantar nerve to the abductor hallucis muscle correlates with the topography of the muscular trigger points. The anatomical structure of the MTrPs may be useful for a better understanding of the pathophysiology of myofascial disorders and provide a basis for surgical and clinical treatments.

<p>Anatomical Study of the Innervation of the Masseter Muscle and Its Correlation with Myofascial Trigger Points</p>

“…The anatomical knowledge of MTPs provides an accurate benchmark for intervention in MPS. Our results, either the ones previously reported regarding the trapezius muscle, 36 gluteus maximus, 37 and abductor halluces, 38 or in the present study, concerning the masseter muscle, demonstrate a strong correlation between distribution of nerve supply and clinical characterized MTPs. The penetration areas of the masseteric nerve may correlate to MTPs and serve as a reference to diagnostic and therapeutic procedures.…”

“…This hypothesis was supported by previous investigations on the innervations of the trapezius, gluteus maximu,s and abductor hallucis muscles. [36][37][38] Even there was any indication that MTPs were always in the same location we considered the frequently observed indication of MTPs by Travell and Simons 7 and Simons et al, 8 because there is not any other data about this location in Masseter muscle. Travell and Simons 7 and Simons et al 8 described trigger areas and MTPs in the superficial layer of the masseter muscle: two insertion points near the superior tendon junction, two points in the middle, and two in the lower portion near the insertion.…”

“…We divided the masseter muscle into six areas and considered the whole muscle, and suggest a relationship between innervation and MTPs. The authors have previously studied the nerve supply to the trapezius, gluteus maximus, and abductor hallucis muscles [36][37][38] through similar anatomical approaches and found a close relationship with the MTP regions described clinically by Travell and Simons 7 and Simons et al 8 Notwithstanding the fact that the suggested MTPs locations seem to be pretty accurate, without assigning any absolute significance to those markers, anatomical correlation is still lacking. Kim et al 34 published a very interesting anatomical study of the masseteric nerve branching to the masseter muscle using 12 masseter to establish safe places to botulinum toxin injection and also divided the muscle in six areas.…”

“…In our dissections, we studied the nerve supply of the masseter muscle in six topographic areas according to previous reports [36][37][38] and entry points of the masseteric nerve were found in all sextants of the muscle, although more prevalent in its upper half.…”

Bases anatômicas dos pontos-gatilho do músculo masseter

“…Nosso relato baseou-se na premissa de que os pontos de entrada do nervo no músculo masseter podem ter estreita relação anatômica com pontos-gatilho miofasciais relacionados a distúrbios dolorosos da região facial. Essa hipótese foi estudada nas inervações do músculo trapézio, glúteo máximo e abdutor do hálux (Akamatsu et al, 2015;Wada et al, 2020).…”