Variation of heads of lateral pterygoid muscle and morphology of articular disc of human temporomandibular joint – anatomical and histological analysis

Abstract

To grasp the documented evidences available regarding the cause of the anteriorly displaced human temporomandibular joint (TMJ) disc. With 20 specimens of human TMJ from cadavers, at first the number of heads of lateral pterygoid muscle (LPM) bundles were analysed with macroanatomical method. Secondary histological procedure with haematoxyline and eosine staining and orceine staining were carried out for the same specimens. Macroscopically, in 13 specimens an upper and a lower head of the LPM were present. In the other seven specimens, not only an upper and a lower head, but also a third inner head of the LPM covered with a separate fascia was observed. Histochemically, the specific localization of certain bundles of thick elastic fibres in the antero-medial parts of the anteriorly displaced deformed TMJ disc were observed.

In vivomorphological and functional evaluation of the lateral pterygoid muscle: a diffusion tensor imaging study

“…LPM dysfunction, [1][2][3][4] including muscle hyperfunction, muscle hypofunction and low muscular co-ordination between the two heads of the muscle, is closely associated with temporomandibular joint disorders (TMJDs), thus it is important to evaluate in vivo the morphology and function of the LPM in clinic.…”

Mechanomyographic activity in the human lateral pterygoid muscle during mandibular movement

“…However, there are only few studies (Ioi et al, 2008) using MMG on the masseter muscle, and to date, no reports on the lateral pterygoid muscle or any other muscles in the stomatognathic system. The lateral pterygoid muscle is known to be one of the important muscles for the mechanical stability of the TMJ Juniper, 1984;Hiraba et al, 2000;Fujita et al, 2001). …”

Distribución nerviosa intradiscal en articulaciones temporomandibular humanas mediante técnica de tinción de Sihler: Un enfoque cadavérico descriptivo.

“…Múltiples autores han estudiado la relación positiva existente entre los desplazamientos discales y el rol del músculo pterigoideo lateral (20)(21)(22), y este estudio plantea la relación nerviosa directa entre ambas estructuras, lo que sugiere que la activación muscular postural y funcional podría implicar una consecuente respuesta discal. Son necesarios estudios electromiográficos para determinar esta posible relación.…”

“…El autor propone la activación muscular selectiva de cuadrantes dentro del músculo durante el ciclo masticatorio (23). Otros autores reafirman la participación de estos nervios en la inervación del pterigoideo lateral (20,21,22). Debido a la inervación común, los nervios que alcanzan la zona anterior del disco y que se comunican con la zona posterior y retrodiscal podrían estar determinando movimientos del complejo disco-capsular independiente del movimiento condilar durante estas activaciones selectivas en funciones musculares específicas.…”