Variant anatomy of the buccal nerve / 대한해부학회지

Knowledge of the anatomy and variations of the nerves of the oral cavity is important to surgeons who operate this region. Herein, we report a rare case of a buccal nerve with two distinct roots. The anatomy of this case and its clinical applications is discussed.

Study of descendent course of buccal nerve in adults individuals / Estudio del trayecto descendente del nervio bucal en individuos adultos

The knowledge of the buccal nerve anatomy is of fundamental importance not only for the anesthesia but also for a safe intervention in the retromolar area. The aim of this work was to study its trajectory, in the area where it is related to the anterior margin of the ramus of the mandible, therefore providing important data for a safe intervention in the region. In this study we used 10 hemi-heads from male and female adults, from different ethnic groups. They were fixed in formol, and belong to the Anatomy Laboratory at the Faculty of Dentistry in Araraquara UNESP. These hemi-heads were dissected by lateral access, preserving the buccal nerve in its trajectory related to the anterior margin of the ramus of the mandible until its penetration in the buccinator muscle. Next, we desinserted the masseter muscle so that all the ramus of the mandible were exposed. Then, the following measurements were carried out: from the base of the mandible until the buccal nerve and from the base of the mandible until the apices of the mandibular coronoid process. These measurements were accomplished with a Mitutoyo CD-6'' CS digital paquimeter. The following average values were obtained: 32.26 mm (to the left side) and 32.04 mm (to the right side), from the base of the mandible until the buccal nerve and 59.09 mm (to the left side) and 58.95 mm (to the right side) from the base of the mandible until the apices of the coronoid process. We have concluded that normally, the buccal nerve crosses the anterior margin of the ramus of the mandible in an area which is above the superior half of the ramus of the mandible and also that the interventions in the retromolar region do not offer great risks of injury in the buccal nerve.

El conocimiento de la anatomía del nervio bucal es de importancia fundamental no sólo para la anestesia, sino también para una intervención segura en la zona retromolar. El objetivo de este trabajo fue estudiar la trayectoria del nervio bucal, en la zona en que se relaciona con el margen anterior de la rama de la mandíbula, proporcionando datos importantes para una intervención segura en la región. En este estudio fueron utilizadas 10 hemi-cabezas de hombres y mujeres adultos, de diferentes grupos étnicos. Las cabezas fueron fijadas en formol, y pertenecen al Laboratorio de Anatomía de la Facultad de Odontología de Araraquara UNESP. Las hemi-cabezas fueron disecadas por medio de un acceso lateral, preservando al nervio bucal en su trayectoria en relación con el margen anterior de la rama de la mandíbula hasta su penetración en el músculo buccinador. A continuación, el músculo masetero fue desinsertado de modo que toda la rama de la mandíbula fue expuesta. A continuación, se llevaron a cabo las siguientes mediciones: desde la base de la mandíbula hasta el nervio bucal y de la base de la mandíbula hasta los ápices de los procesos coronoides mandibular. Estas mediciones se realizaron con un caliper digital CD-6'' CS Mitutoyo. Los siguientes valores promedio fueron obtenidos: 32,26 mm (a la izquierda) y 32,04 mm (a la derecha) de la base de la mandíbula hasta el nervio bucal y 59,09 mm (a la izquierda) y 58,95 mm (a la derecha) de la base de la mandíbula hasta los ápices de los procesos coronoides. En conclusión, normalmente, el nervio bucal cruza el margen anterior de la rama de la mandíbula en una zona que está por encima de la media superior de la rama de la mandíbula, y también que las intervenciones en la región retromolar no ofrecen grandes riesgos de lesiones en el nervio bucal.

Topographic Anatomy of the Mandibular Nerve Branches Distributed on the Lateral Pterygoid Muscle / 체질인류학회지

According to the electromyographic study, the superior and inferior heads of lateral pterygoid, one of the masticatory muscles, are known to perform the reciprocal actions in mandibular movements; the superior head is active in closing movement, whereas the inferior head is active in opening of the jaw. Through these two reciprocal actions of these two heads, the articular disk of TMJ is seated in its resting position. Many reports regarded the superior and inferior heads of the lateral pterygoid as functionally independent muscles, but from a morphological point of view, the origin of the independent nerve innervation and intramuscular branching patterns of the mandibular nerve are unclear. Twenty -four adult hemi -sectioned heads were dissected to clarify the topography of the nerve distribution on two heads of lateral pterygoid and also to determine the anatomico -clinical relevance related with temporomandibular disorder. Most buccal nerves were found to run between the superior and inferior heads of the lateral pterygoid (21 cases, 87.5 %). In 3 cases, buccal nerves passed through the inferior head of the lateral pterygoid (12.5%). In front of the ascending ramus region, most buccal nerves ran in front of the temporalis without being entrapped within the temporalis (16 cases, 66.7%). However, in 8 cases buccal nerve passed in front of the temporalis being entrapped within the anterior fiber of the temporalis (33.3%). In this study, the mandibular nerve trunk was located intimately to the lateral pterygoid. Both heads of the lateral pterygoid muscles were innervated from the mandibular nerve branches, but the patterns of nerve distribution were various. Nerves innervated to the superior head of the lateral pterygoid had different origin. Only in 45.8% (11 cases), they originated from the buccal nerve. In 16.7% (4 cases) the nerve branches originated from the anterior deep temporal nerve only, and in 12.5% (3 cases) from the buccal and anterior deep temporal nerve. In contrast, nerves innervated to inferior head of the lateral pterygoid showed different pattern of distribution. In 58.3 %, nerves distributed on the inferior head originated from both the buccal and mandibular nerve trunk. In 20.8%, they originated from the buccal nerve only, in 12.5% from the mandibular nerve trunk only. In seven categories of the distribution of mandibular nerve branches, in only 20.8% (5 cases), both the superior and inferior heads of the lateral pterygoid had the common source of nerve innervation, the buccal nerve. In contrast, in 45.9% (11 cases) additional nerve twigs from the mandibular nerve trunk were distributed on the inferior head of the lateral pterygoid muscle. Author observed the pterygoid loop (ansa pterygoidea) located between the mandibular nerve trunk and the nerve innervating to the lateral pterygoid in 4 cases. In addition, the intramuscular nerve loop within the inferior head of lateral pterygoid was observed in 5 cases. Summarizing these results, besides the buccal nerve mentioned in an anatomical textbook, nerve twigs originating directly from the mandibular nerve trunk innervated to the lateral pterygoid and the ones originating from the anterior and middle deep temporal nerves distributed on the lateral pterygoid muscle in various manners. Considering the various patterns of nerve distribution on the lateral pterygoid, author concluded that the two heads of the lateral pterygoid are controlled by independent innervation. Furthermore, we found out that nerve entrapments and nerve communications are related with symptoms of temporomandibular disorder and with possible collateral route of motor innervation to the facial expression muscles, respectively.