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Mini Review Volume 17 Issue 3
Deep portion of the human temporalis muscle:clinical and functional insights
Edgardo Hector Fuentes Anabalon
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Correspondence: Edgardo Hector Fuentes Anabalon, Autonomous University of Chile, Tel Tel 3208763892
Received: July 21, 2025 | Published: October 21, 2025
Citation: Anabalon EHF. Deep portion of the human temporalis muscle: clinical and functional insights. J Otolaryngol ENT Res. 2025;17(2):78‒79. DOI: 10.15406/joentr.2025.17.00572
Abstract
The deep portion of the human temporalis muscle, often overlooked or inconsistently described in classical anatomical texts, has gained increasing attention due to its functional and clinical significance. From early anatomical observations by Eisler1 and Zenker2 to more recent studies by Geers et al.3 and Fuentes et al.,4 this structure has been linked to mandibular movements, lateralization, and potential involvement in neuropathic pain. Despite its importance, significant gaps remain in understanding its precise morphology, innervation, and clinical implications. This Mini Review aims to clarify conflicting perspectives, identify research gaps, and explore potential advancements in the diagnosis and treatment of disorders related to this muscle. To enhance the comprehensibility of current academic debates, the sources of controversies surrounding its role in neuropathic pain and parafunctional disorders are discussed, along with the reasons for divergent findings across different studies.
Keywords: temporalis muscle, mandibular lateralization, neurovascular compression, gamma loop, trigeminal neuralgia
Introduction
The deep portion of the temporalis muscle has historically been either omitted from anatomical literature or described with variability. Early texts, such as Testut’s5 recognized its presence, while others, like Rouviere’s,6 did not. Anatomical pioneers, including Eisler and Zenker, provided foundational descriptions that later evolved with electromyographic, histological, and imaging studies.3 Characterized by a distinct tendon insertion, this structure has been implicated in functional roles such as mandibular lateralization and clinical conditions like trigeminal neuralgia. However, its precise role within the masticatory system and broader craniofacial functions remains insufficiently understood.
Morphological aspects
Cadaveric studies reveal that the deep portion of the temporalis muscle is elongated, with a thicker origin near the sphenoidal line and a thinner inferior insertion.3 Its fibers run obliquely from medial to lateral, inserting on the medial side of the coronoid process. Zenker described a tendinous ridge enveloping the maxillary nerve, suggesting potential implications for neurovascular compression syndromes. Recent imaging studies have confirmed its anatomical distinction from the main temporalis tendon.7 However, further anatomical research is necessary to elucidate its precise relationship with adjacent neurovascular structures.
Functional aspects
Electromyographic analyses by Zenker and Fuentes indicate that this muscle activates during mandibular lateralization with occlusal contact but not during mouth opening. The gamma loop mechanism and spindle density- critical to neuromuscular control - have been hypothesized to play a role in its hyperactivity under stress conditions.8 This could explain its involvement in parafunctional activities such as bruxism. Given the limited number of comprehensive studies on its spindle density and innervation patterns, further research is required to clarify its precise neuromuscular function.
Clinical relevance
The deep temporalis muscle has been implicated in various clinical conditions, including the treatment of facial paralysis9 and a possible role on trigeminal neuralgia. Interventions such as tenotomy or botulinum toxin injection have shown promising results in managing neurological compression and parafunctional disorders. However, the lack of standardized treatment protocols and the variability of patient responses highlight the need for further clinical trials. Including more detailed case reports or epidemiological data could strengthen the clinical relevance of this topic and provide valuable insights for treatment strategies.
Discussion
The deep portion of the temporalis muscle represents a transitional structure within the masticatory system, exhibiting characteristics of both cranial and mandibular muscles. Its unique anatomy and functional properties suggest a significant role in mandibular biomechanics and craniofacial pain syndromes. However, controversies persist regarding its exact involvement in neuropathic pain and parafunctional disorders. The absence of comprehensive studies on its spindle density, innervation patterns, and gamma loop activation limits our understanding of its neuromuscular physiology. Future research should prioritize longitudinal imaging studies, biomechanical modeling, and controlled clinical trials to establish its role in diagnosis and therapy.
Conclusion
In conclusion, the deep temporalis muscle is a crucial yet underappreciated component of craniofacial anatomy. Addressing current knowledge gaps will improve diagnostic accuracy and therapeutic approaches for related disorders, fostering advancements in both basic and clinical sciences. Standardized methodologies and interdisciplinary collaboration will be essential to further elucidate its functional and clinical significance.
Conflict of interest
The author declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest
Author contributions
EF designed the review structure and conducted the literature review.
Funding
This work received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.
Acknowledgments
The author would like to thank Autonomous University of Chile.
References
- Eisler P. The muscles of the trunk. In: von Bardeleben K, ed. Handbook of Human Anatomy. Vol 2/2/1. Gustav Fischer; 1912:197–220.
- Zenker W. On some new findings on the human temporal muscle. Z Anat Developmental History.1955;118:355–368.
- Geers C, Nyssen-Behets C, Cosnard G, et al. The deep belly of the temporalis muscle: an anatomical, histological and MRI study. Surg Radiol Anat. 2005;27(3):184–191.
- Fuentes E, Frugone R, Paolinelli C, et al. Electromyographic activity of the sphenomandibularis and lateral pterygoid human muscles during mandibular lateral movements. Chirurgia (Bucur). 2012;25(2):97–99.
- Testut L. Treatise on Human Anatomy. 3rd ed. Octave Doin; 1905:707–709.
- Rouviere H. Descriptive and topographical human anatomy. Vol 1. Masson; 1954:133.
- Yu SK, Kim TH, Yang KY, et al. Morphology of the temporalis muscle focusing on the tendinous attachment onto the coronoid process. Anat Cell Biol. 2021;54(3):308–314.
- Wieckiewicz M, Paradowska-Stolarz A, Wieckiewicz W. Psychosocial aspects of bruxism: the most paramount factor influencing teeth grinding. Biomed Res Int. 2014;2014:469187.
- Labbe D, Huault M. Lengthening temporalis myoplasty and lip reanimation. Plast Reconstr Surg. 2000;105(4):1289–1297.
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