Int J Anat Res 2017, 5(2.3):3927-29. ISSN 2321-4287 3927

Case Report

UNUSUAL COMMUNICATION BETWEEN THE MYLOHYOID NERVEAND LINGUAL NERVE IN A NORTH INDIAN MALE CADAVER: ITSCLINICAL SIGNIFICANCEPadamjeet Panchal *, Jacques Britto, Atulya Prasad.

ABSTRACT

Address for Correspondence: Dr. Padamjeet Panchal, Department of Anatomy, All India Instituteof Medical Sciences, Patna, Phulwarisharif, Patna, Bihar, India – 801507.E-Mail: drpadamjeetp@aiimspatna.org

Variations and communications are frequently encountered in the branches of posterior division of the mandibularnerve. These unusual anatomical variations are rare and least conclusively described in the literature. Duringroutine dissection, we found the presence of unusual communicating branch between mylohyoid nerve andlingual nerve in a middle aged male cadaver. Its clinical significance and surgical implications are also discussedin this report along with the possible role of the alternate path of sensory innervation of the tongue.KEY WORDS: Mylohyoid nerve, Lingual nerve, Communicating branch, Auriculotemporal nerve, Inferior alveolarnerve, Mandibular nerve.

INTRODUCTION

International Journal of Anatomy and Research,Int J Anat Res 2017, Vol 5(2.3):3927-29. ISSN 2321-4287

DOI: https://dx.doi.org/10.16965/ijar.2017.221

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DOI: 10.16965/ijar.2017.221

Department of Anatomy, All India Institute of Medical Sciences, Patna, Phulwarisharif, Patna, Bihar,India.

Received: 15 Apr 2017Peer Review: 17 Apr 2017Revised: None

Accepted: 23 May 2017Published (O): 30 Jun 2017Published (P): 30 Jun 2017

(LN), inferior alveolar nerve (IAN) and auricu-lotemporal nerve (ATN). The mylohyoid nerve(MHN) is a branch of the IAN, which arisesbefore its entry in the mandibular foramen. Thenerve then passes downward and anteriorlywithin the mylohyoid groove on the medialsurface of the mandible. The nerve coursesanteriorly and parallel to the mylohyoid muscleand giving branches that provide motor inner-vation to the mylohyoid and anterior belly of thedigastric muscles.The mylohyoid muscle plays an important rolein chewing, swallowing, respiration andphonation [1]. It has been analyzed that the MHNmay carry a sensory innervation of the chin andthe lower incisor teeth through an alternate path-way. Abnormal communications most commonly

Trigeminal nerve is the largest of all cranialnerves and it is considered as mixed nerve. It isattached to the ventral surface of pons by tworootlets large sensory and small motor root. Theconvex antero- lateral margin of the trigeminalganglion gives attachment to three divisions -ophthalmic, maxillary and mandibular in themiddle cranial fossa. The sensory mandibulardivision of the trigeminal nerve is joined by themotor root to form the mandibular nerve (MN),while its maxillary and ophthalmic divisionsconstitute predominantly sensory fibres. The MNimmediately after its exit from the skull throughthe foramen ovale, divides into the anterior andposterior branches. Branches of the posteriordivision of the MN – namely the Lingual nerve

Int J Anat Res 2017, 5(2.3):3927-29. ISSN 2321-4287 3928

Padamjeet Panchal, Jacques Britto, Atulya Prasad. UNUSUAL COMMUNICATION BETWEEN THE MYLOHYOID NERVE AND LINGUAL NERVEIN A NORTH INDIAN MALE CADAVER: ITS CLINICAL SIGNIFICANCE

encountered among the posterior divisionbranches of the mandibular nerve.

During the routine M.B.B.S practical, dissectionof head and neck region of a middle-aged malecadaver in the Department of Anatomy, AIIMS,Patna, a rare unusual communication betweenthe MHN and LN was noted. Dissection of Infra-temporal region was done carefully and all thebranches of MN was traced. The MHN branchof the IAN was traced up to the mylohyoidmuscle. The LN was dissected until its entranceinto the submandibular region.

MATERIALS AND METHODS

In the present case, a thin communicatingbranch arising from the MHN at the below thelevel of mandibular foramen close to the inter-mediate tendon of digastric muscle, that joinedLN (Figure 1 and 2). Thereafter, the MHN piercedthe mylohyoid muscle and followed its normalcourse and branching pattern. No other anatomi-cal variations were found in the origin of IAN orthe LN. In addition, no communicating branchesbetween these two nerves were found. The LN,after receiving this communicating branch fromthe MHN, was observed taking its normal courseand branching pattern.

OBSERVATIONS

Many studies have revealed that there is lot ofvariation and communication between branchesof the posterior division of MN [2].The presence of communicating branchesbetween the IAN and LN are very commonlymentioned in most of the anatomical textbooks[3]. Nevertheless, a communicating branchbetween the MHN and LN is seldom describedby authors in the literature.In present case report, a rare unusual commu-nication between MHN and LN on left side wasseen. Thotakura et al [4] studied 36 specimens,in two specimens they found abnormal commu-nication between MHN & LN. Simarjit kaur et al[5] has also reported communication betweenthe MHN and LN.This communication occur after the LN passesin close relation to the third molar tooth. Sincethis close relationship of the LN and the thirdmolar tooth makes it susceptible to injuryduring the third molar extraction [6]. The unusualcommunication can be an alternate pathway forthe lingual general sensory fibres as well as thesensation from the teeth or chin skin that maypass through the MHN and IAN to joins theposterior division of mandibular nerve. This viewis also supported by Kilic C et al [7]. Thepresence of a nerve communication like the onedescribed in this case would help in the LNfunction recovery [8]. A communicating branchfrom the MHN to the LN is developmental inorigin and assumed to convey proprioceptivefibres from the mylohyoid muscle through theLN [9].These anatomical variations are explained onthe basis of development. MN develops fromfirst arch by neural crest cells [10]. It has beensuggested that during the embryonic develop-ment few of the proteins liberated from somitessuch as T -cadherin, may be responsible for neu-ral development. Abnormal expression of theseproteins may lead to delayed regression ofarches and anomalous communication betweennerves [11,12].

The presence of such communicating nervesamong the posterior division branches of theyare development in origin and thought to serveas an alternative route for maintaining the

CONCLUSION

Int J Anat Res 2017, 5(2.3):3927-29. ISSN 2321-4287 3929

Padamjeet Panchal, Jacques Britto, Atulya Prasad. UNUSUAL COMMUNICATION BETWEEN THE MYLOHYOID NERVE AND LINGUAL NERVEIN A NORTH INDIAN MALE CADAVER: ITS CLINICAL SIGNIFICANCE

functional integrity of the structures innervatedby it. Knowledge of these alternative pathwaysis important in helping clinicians to obtaincomplete dental anesthesia as well as surgeonsto avoid unnecessary complications duringsurgeries and in dental practice. Further researchis necessary to obtain more detailed knowledgeregarding variations of position and course ofthe mylohyoid nerve.ABBREVIATIONS

MN - Mandibular NerveLN - Lingual NerveIAN - Inferior Alveolar NerveATN - Auriculotemporal NerveMHN - Mylohyoid Nerve

[7]. Kilic C, Kamburoðlu K, Özen T. A mylohyoid nervetraveling within the mandibular canal: a Case Re-port. Trakya univ tip fak derg 2010;27(3):297-299.

[8]. Sassoli Fazan VP, Rodrigues Filho OA, Matamata F.Communication between the mylohyoid and lingualnerves: cl inical implications, Int J Morphol,2007;25(3):561–564.

[9]. Furusawa K, Yamaoka M, Fujimoto K, Kumai T. Roleof proprioceptors in the mylohyoid muscle. BrainRes Bull 1994;35:233-6.

[10]. Bronner-Freser M. Environmental influences on neu-ral crest cell migration. J Neurobiol. 1993;24(2):233-247. Doi:10.1002/neu.480240209.

[11]. Debby-Brafman A, Burstyn-Cohen T, Klar a, KalcheimC. F-spondin, expressed in somite regions avoidedby neural crest cells, mediates inhibition of dis-tinct somite domains to neural crest migration.Neuron. 1999;22(3):475-488. Doi: 10.1016/so896-6273(00)80703-5.

[12]. Ranscht B, Bronner-Fraser M. T-cadherin expres-sion alternates with migrating neural crest cells inthe trunk of the avian embryo. Development.1991;111:15-22.

Conflicts of Interests: None

REFERENCES

[1]. Ren M, Mu L. Intrinsic properties of the adult humanmylohyoid muscle: Neural organization, fiber-typedistribution, and myosin heavy chain expression.Dysphagia 2005;20:182-94.

[2]. Sakamoto Y, Akita K. Spatial relationships betweenmasticatory muscles and their innervating nervesin man with special reference to the medial ptery-goid muscle and its accessory muscle bundle. SurgRadiol Anat 2004;26:122-7.

[3]. Berkovitz B. Oral cavity In: Standring S (Ed.) Gray’sAnatomy: The Anatomical Basis of Clinical Prac-tice. 41st Ed. New York: Elsevier 2016. p.527.

[4]. Thotakura B, Rajendran SS, Gnanasundaram V,Subramaniam A. Variations in the posterior divi-sion branches of the mandibular nerve in humancadavers. Singapore Med J. 2013; 54(3):149-151.Doi: 10.11622/smedj.2013051

How to cite this article:Padamjeet Panchal, Jacques Britto, Atulya Prasad. UNUSUALCOMMUNICATION BETWEEN THE MYLOHYOID NERVE ANDLINGUAL NERVE IN A NORTH INDIAN MALE CADAVER: ITSCLINICAL SIGNIFICANCE. Int J Anat Res 2017;5(2.3):3927-3929.DOI: 10.16965/ijar.2017.221