Anatomical variations of the anterior belly of the digastric muscle / Variaciones anatómicas del vientre anterior del músculo digástrico

A routine dissection of the digastric muscle reflected that it originated by two muscle bellies namely. the anterior and posterior belly which are connected by an intermediate tendon (IT). These bellies originated from the mastoid process of the temporal bone and the digastric fossa of the mandible respectively. The digastric muscle serves as an important surgical landmark in surgical interventions involving the submental area however, accessory bellies may interfere with surgical intervention in this area. Therefore, this study aimed to document the occurrence of the anatomical variations in the anterior belly of the digastric muscle (ABDM) in a selected number of cadaveric samples. Ten bilateral adult cadaveric head and neck specimens (n = 20) were macro-dissected in order to document the morphology of the digastric muscle. The accessory bellies in the ABDM was observed in 60 % of the specimens. Unilateral and bilateral variations were observed in 20 % and 30 % of the specimens, respectively. These accessory bellies originated in the digastric fossa, ABDM, IT and hyoid bone, and inserted into the mylohyoid raphe, mylohyoid muscle and hyoid bone. In addition, an anomalous main ABDM was observed in 10 % of the specimens inserting through a transverse tendon into the hyoid bone. Variations in the digastric muscle are common especially the accessory bellies, therefore, a comprehensive understanding of these anatomical variations could be of clinical importance to the surgeons during head and neck radiological diagnosis and surgical interventions.

Una disección de rutina del músculo digástrico refleja que se éste originaba por dos vientres musculares, anterior y posterior conectados por un tendón intermedio (IT). Estos vientres se originaban a partir del proceso mastoide del hueso temporal y de la fosa digástrica de la mandíbula, respectivamente. El músculo digástrico sirve como un hito quirúrgico importante en las intervenciones que involucran el área submental. Sin embargo, los vientres accesorios pueden obstaculizar la intervención quirúrgica en esta área. Por lo anterior, este estudio tuvo como objetivo documentar observaciones de las variaciones anatómicas en el vientre anterior del músculo digástrico (VAMD) en un número seleccionado de cadáveres. Las muestras consistieron en 10 cabezas y cuellos cadavéricos de individuos adultos, estudiadas bilateralmente (n = 20). Estas muestras fueron disecadas para documentar la morfología del músculo digástrico. Los vientres accesorios en el VAMD se observaron en el 60 % de los casos. Se observaron variaciones unilaterales y bilaterales en el 20 % y el 30 % de las muestras, respectivamente. Estos vientres accesorios se originaban en la fosa digástrica, VAMD, IT y hueso hioides, y se insertaban en el rafe milohioideo, el músculo milohioideo y el hueso hioides. Además, se observó un VAMD principal anómalo en el 10 % de las muestras que se insertaban a través de un tendón transversal en el hueso hioides. Las variaciones en el músculo digástrico son comunes, especialmente los vientres accesorios, por lo tanto, un conocimiento completo de estas variaciones anatómicas podría ser de importancia clínica durante el diagnóstico radiológico de cabeza y cuello y en las intervenciones quirúrgicas de la región.

Accessory belly of flexor digitorum superficialis - case report of a rare variant.

Variations of the muscles pose a challenge to diagnosis and knowledge about them is important during surgeries and other interventions. At times these variations may cause symptoms per se. Variations of the Flexor digitorum superficialis: a muscle of the anterior compartment of forearm, are not very common. We present a rare variation of this muscle in the right upper limb of a male cadaver. The variant was an accessory belly arising from and under the Flexor digitorum superficialis and inserting into the base of proximal phalanx of the index finger. We also review the evolutionary and embryological concepts of such variations.

Anatomical variation of the anterior belly of the digastric muscle: case report and clinical implications

The digastric muscle is a suprahyoid muscle composed of two bellies connected by an intermediate tendon.This muscle participates in deglutition and mandibular movements. The anterior belly of the digastric muscleis localized superficially to the mylohyoid and deeply to the platysma muscle. During dissection of this regionof an embedded cadaver, an accessory anterior belly of digastric muscle was observed bilaterally. The accessorybellies were similar but not symmetrical. They were composed of two segments, one long and one short, onboth sides, and when observed together these appeared to form the letter “X”. The accessory fibers, on bothsides, originated from the anterior digastric muscle and inserted medially to the digastric fossa. Anatomicvariations of the digastric muscle may influence mastication and deglutition. Moreover, the accessory digastricmuscle affects diagnostic imaging and therapeutic procedures in head and neck surgery and must be consideredin procedures involving this area.

Anatomic Variation of the Anterior Belly of Digastric Muscle and Positional Relationship between the Posterior Belly of Digastric and Stylohyoid Muscle / 체질인류학회지

The digastric muscle is located in the suprahyoid region which consists of anterior belly, intermediate tendon and posterior belly. This muscle is an important landmark when performing an operation of submental and upper neck region. Previous researches have reported about variations of the anterior and posterior belly of digastric muscle. However, there are few studies about the general morphology of the digastric muscle and the relationship with surrounding muscles. The purpose of this study was to analyze the morphology of the anterior belly of digastric muscle and confirm the topographic relationship between the digastric muscle and the stylohyoid muscle of Korean. Thirty-four cadavers (21 males, 13 females; mean age 65 years; range 24~89 years) were used in this study. The skin, subcutaneous tissues, superficial fascia and platysma were removed and a detailed dissection was performed, with extreme care being taken not to damage underlying the muscles of submental and upper neck region. After the dissections, all specimens were sketched and photographed. In 8 specimens, we observed the accessory bellies of the anterior belly of digastric muscle. We classified the accessory bellies into the crossover type (five specimens, 14.7%) that cross the mandibular raphe and unilateral type (three specimens, 8.82%). The findings resulting from observation of the anatomical relationship between the posterior belly of digastric and stylohyoid muscles, the posterior belly of digastric muscle perforated the stylohyoid muscle in 32 cases (65%) out of 49 sides. This case was subdivided into the belly of the stylohyoid muscle lean to the lateral (twenty-one specimens, 42.9%) or medial side (eleven specimens, 22.4%) of the posterior belly of digastric muscle. In 17 specimens (35%), the stylohyoid muscle existed on the medial side of the posterior belly of digastric muscle.