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A Cadaveric Analysis of Morphological Variations of the Anterior Belly of the Digastric Muscle
Author(s) -
Anderson Hana,
Tucker Richard P.
Publication year - 2020
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2020.34.s1.04980
Subject(s) - digastric muscle , anatomy , cadaver , cadaveric spasm , medicine , population , muscle belly , tendon , environmental health
The digastric is a suprahyoid muscle characterized by two distinct muscle bellies, anterior and posterior, linked by an intermediate tendon. The anterior belly of the digastric muscle (ABDM) displays a wide array of anatomical variations and there is rich literature documenting its variations, going back as early as the 18 th century. A wide range of prevalence of ABDM variations is found in the literature, ranging from as low as ~5% to as high as ~70% of the examined cadavers in each study. Morphologies of ABDM variations are also fairly complex, including fusion of the right and left ABDM, addition of a unilateral or bilateral accessory muscle, and composites of multiple accessory muscles. Reflecting the common embryological origin in the first pharyngeal arch and shared innervation of the mandibular branch of the trigeminal nerve, ABDM variations frequently also involve the mylohyoid muscle. In the current study, we sought to improve our understanding of ABDM variations in the ethnically diverse whole‐body donor population in Northern California. Specific aims were: (1) To determine the frequency of ABDM variations in cadavers donated to the UC Davis Body Donation Program, (2) To classify the observed ABDM variations in this population using the nomenclatures proposed by Zlabek (1933) and Yamada (1935), and (3) To investigate the innervation and arterial supply to ABDM accessory muscles. Forty‐eight cadavers (male 23, female 25, average age 75) were examined over a two‐year period and ABDM variations were identified in 15 donors (31.2%). These variations were classified as: (1) Atavistic (Atavique) type – 2 cadavers, (2) Origin (Antérieur) type – 5 cadavers, (3) Insertion (Postérieur) type – 5 cadavers, (4) Mixed (Mixte) type – 1 cadaver, and (5) Composite (Composé) type – 2 cadavers. Innervation and arterial supply were determined for one of the atavistic types and one of the origin types. It was found that innervation was from the nerve to mylohyoid and arterial supply was from the submental artery originating from the facial artery, which fit to the typical innervation and blood supply to the ABDM. In summary, on average we found ABDM variations in 1 in 3 individuals in the local Northern California population. Knowledge of a high prevalence of ABDM variations in the general population as reported here would be valuable information when an operation or examination is performed in the submental region.