Branch of Mylohyoid and Lingual Nerves on Submandibular and Submental Triangles

Abstract

Summary: The mylohyoid nerve (MN) displays several branches in the posterior, intermediate, and anterior region of the mylohyoid muscle (MM) as it courses on the internal surface of the mandibular body. Branches in the intermediate region were found in 66% of the cases (272 out of 413 sides). In the submandibular triangle, one or two large branches of the MN communicated with the lingual nerve at submandibular triangle and submental triangle in 1.45% of the cases (6 out of 413 sides). These distributions of nerve supply are an important in the operations of radical neck dissection on the submandibular triangle.The mandibular nerve divides into two branches, the lingual nerve (LN) and the inferior alveolar nerve (IAN), at the mandibular notch. The IAN descends to the mandibular nerve branches on the inner mylohyoid muscle (MM). Mandibular nerve has anastomotic branches connecting to the lingual nerve (LN) after leaving laterally from the foramen ovale (Clemente, 1985). Chorda tympani join the LN in the deep region behind the lateral pterygoid muscle. The IAN is also branched into the mylohyoid nerve (MN) at the mandibular foramen. There are a few communications between the MN and the LN in the submental triangle. Kameda (1952) has reported the MN communicated with the LN in 46.3% (74 out of 160 sides) of the cases.The communication rate of the LN and the MN in Kameda reports (1952) is high in compared to that of our data, however, this reports is no detailed in course, supply, and any region in two nerves. Radical neck dissection needs the detailed information of nerve supply in the submandibular triangle (Beahrs, 1977;Swift, 1970;Feldman and Applebaum, 1977). Trail and Lubritz (1974) also indicated complete removal of tumors on the submandibular gland required radical excision of tissue around them, including neck dissection. Therefore we observed nerve supply on submandibular triangle and submental triangle in detail. Materials and MethodsWe examined the mylohyoid nerve branches under a binocular microscopy, 413 sides of 272 mandibles from adult Japanese cadavers (161 males and 111 females; 141 both sides, 60 right side only and 71 left side only) for passage and supply. We also observed the communications between the mylohyoid nerve (MN) and the lingual nerve (LN) in the submandibular triangle and submental triangle. Using forceps, we removed the entire mucous membrane, the connective tissues of the mylohyoid muscle (MM), parts of the ramus of the submental arteries, and veins at submandibular triangle and submental triangle. In each case, the communications between the MN and the LN and their distribution were analyzed and photographed. ResultsWe observed the course and the communications between the mylohyoid nerve (MN) and the lingual 45 * Correspondence to: Iwao Sato,

Analysis of the mylohyoid nerve in elderly Japanese cadavers for dental implant surgery

“…The number of nerve branches entering the MM was evidently more than that of the anterior belly of the digastric muscle. Communications between the MN and LN were mainly found between the premolar and molar region of the mandible, which has been shown to occur at a frequency ranging from 45 to 66% (46.3% Kameda & Uber den, 1952; 66% Sato et al, 2004, this study, 63%). It is interesting to point out that the communication occurs between the LN and MN, both of which originate from the mandibular nerve.…”

“…The posterior trunk of the MN gives rise to the main sensory nerves, that is, the auriculotemporal, lingual, and inferior alveolar nerves and motor branches to the MM and the anterior belly of the digastric muscle (Brennan, Webb, Kemidi, Spratt, & Standring, 2008). Communication between the MN and LN was also found at some frequency (46.3% Kameda & Uber den, 1952; Sato, Sunohara, Ueno, & Yoshida, 2004, 66%). In dental implant or oral surgery, the inner surface of the mandible has become an important area for lingual flap dental treatment (Urban et al, 2018).…”

<p>Anomalies and Clinical Significance of Mylohyoid Nerve: A Review</p>

“…Sato et al reported, in 1.45% of cases, two large communications between the MHN with the LN in submandibular and submental regions. 25 However, Kameda reported 46.3% connection between these nerves. 26 An unusual communication between these nerves also was reported after the LN crossed the mandibular third molar 3 ( Figure 3).…”

Clinical anatomy of the nerve to the mylohyoid

“…In these five cases, all of the NMs ran posteromedial to the IAN [22]. Although most unusual connections between the NM and the lingual nerve (LN) have been reported as case reports [32324], Sato et al [25] investigated this anomaly and revealed that in 1.45% of cases (6/413), one or two large branches of the NM connected with the LN in the submandibular or submental triangles. This incidence was significantly different from that reported by Kameda (1952) [26] who identified communicating branch of the LN and NM in the submental triangle in 46.3% of the cases (74/160).…”