The submental arrowhead variation of the mylohyoid and anterior belly of the digastric muscles

Abstract

Purpose-Submental anatomical variation is of clinical importance with regard to head and neck surgeries. One such anatomical variation is that of additional musculature joining the intermediate tendon of the digastric muscle to the midline of the mylohyoid musculature-a variation which this report refers to, accordingly, as an arrowhead variation. Though the arrowhead variation has been described in several case reports, it has not been subject to cross-sectional study. The purpose of this study is to determine the prevalence of the arrowhead variation. Methods-Prevalence of the arrowhead variation was assessed in 19 cadavers via gross dissection. Results-Two of the 19 cadavers (10.5%) were found to have arrowhead variations. The arrowhead variation was found in one male (1:11; 9.1%) and one female (1:8; 12.5%), respectively. Conclusions-This report demonstrates that the submental arrowhead variation of the anterior digastric and mylohyoid musculature has been reported in isolated case reports since the nineteenth century. This report is the first cross-sectional study of the arrowhead variant, identifying it in approximately one in ten individuals and in both sexes. Therefore, the presence of an arrowhead variation should be regularly considered with regard to diagnosis of submental masses. Likewise, the arrowhead variation should be considered in the preoperative planning of the myriad operations performed in the submental region.

A cadaveric analysis of anatomical variations of the anterior belly of the digastric muscle

“…2G). The arrangement of these three AB accessory muscles is similar to the variation reported by Zdilla et al (2018) [27]. The second complex type variation, shown in Figure 2H, consisted of insertion and origin type variations.…”

“…Clinically, structural variations of the ABDM have implications in surgeries involving the muscles of the submental region such as correction of facial paralysis and an array of cosmetic surgeries for improving the frontal neck contour [5,9,10,23,26]. The ABDM variations, especially those with atavistic type variation and robust AB accessory muscles, could cause misidentification of the suprahyoid muscle groups which affects diagnosis involving the submandibular region [1,26,27]. Therefore, attracting attention to the frequent occurrence and morphological complexity of ABDM variations in the general population has significant clinical importance.…”

Submental Anatomical Variations: The Uniqueness of a Common Variation

“…m. Mento-hyoid (Macalister) 4 and m. Interdigastricus. 6 The literature presents records of the variations in the digastric muscle dating from 17377 and since then several authors have published anatomical studies Fernandes LC, Prado PSA Submental Anatomical Variations: The Uniqueness of a Common Variation in the submental and submandibular anatomical regions 8,9,10,11,12,13,14,15,16,17,18,19 as well as many others who have been publishing their findings as case reports (see the list of authors in Table 1).…”

“…Therefore a solid understanding of the anatomy and recognition of these variations in the analysis of imaging exams such as Computed tomography (CT) and Magnetic resonance imaging (MRI) and in surgical procedures is required to avoid misdiagnosis, imprecision in surgical procedures as well as in emergency interventions. 10,18,22,23,24…”

Anatomical insights of the mylohyoid for clinical procedures in dentistry

“…The MH is a partial barrier between the submandibular and sublingual spaces; therefore, it can be related to the spread of odontogenic infection, such as Ludwig's angina. It can also lead to infection in the upper neck region in presence of a mylohyoid defect (Bender‐Heine & Zdilla, 2018; Zdilla, Mangus, Swearingen, Miller, & Lambert, 2018). The MH with herniation of the sublingual gland and fat tissue can cause difficulty in establishing the differential diagnosis (Yang et al, 2016).…”