Anatomical Bases of the Temporal Muscle Trigger Points

Abstract

Method: Temporal muscles of 14 adult cadavers were studied. The muscle bellies were divided into six areas, three superior (1.2 and 3) and three inferior areas (4, 5, and 6) lower, according to a Cartesian plane to analyze and describe the entry points of the branches of the deep temporal nerves into the muscle. The branching distribution was analyzed using Poisson log-linear tests with Bonferroni post hoc tests for comparison between groups (sextants) (p < 0.05).

Results: Deep temporal nerve entry points were found in the temporal muscle in all areas. Most of the branches were observed in areas 2 and 5, which coincide with the muscle fibers responsible for mandible elevation and related to the previously described MTPs. Fewer branches were found in areas 1 and 6, where contraction produces mandible retraction.

Conclusion: There is an anatomical correlation between the branching pattern of the deep temporal nerve and temporal muscle trigger points. Adequate knowledge of the innervation of the temporal muscle may help elucidate the pathophysiology of myofascial syndromes and provide a rational basis for interventional or conservative approaches and help surgeons avoid iatrogenic lesions to the deep temporal nerve lesion.

Figure 1

Lateral view of dissected left temporal muscle.

Figure 2

Lateral view of the left temporal muscle. Transverse (AB) and longitudinal (CD) measurements.

Figure 3

Lateral view of the left temporal muscle. Abscissa X, ordered Y, and separation in sextants (1, 2, 3, 4, 5, and 6).

Figure 4

Lateral view showing the deep temporal nerve in the reflected left temporal muscle after removal of the zygomatic arch, yellow color marks the nerve until the entry points into the muscle and the blue wire separating the nerve.

Figure 5

Lateral view of the left temporal muscle. Stars showing the intake of the branches of the deep temporal nerves into the muscle. Points in sextants.

Figure 6

Entry points of the deep temporal nerves in the muscle belly. Grade points average on all sextants and standard deviation.

Figure 7

Correlation between the size of the transverse AB measurement and the number of nerve entry points into muscle.

Figure 8

Trigger points 1, 2, 3, and 4, described by Travell and Simons [9], sites of reflex pain of each point in the colored bands. Sextants 1,2,3,4,5,6, with colored dots showing the intake of the branches of the deep temporal nerves into the muscle of the cadavers used in this study.