Variation and Arrangement of the Digastric Muscle in a Chinese Population

The digastric, a prominent anatomic feature of the head and neck, exhibits clear ethnographic differences in the incidence of variation in its anterior belly (AB) and the relationship of its intermediate tendon (IT) to the stylohyoid (SH). There is a limited amount of information available regarding the digastric in the Chinese population, with most descriptions being individual cases. The present study aims to investigate the variability of AB, elucidate the relationship between IT and SH, and further address the arrangement of individual digastric muscles according to the type of AB and posterior belly (PB) of the digastric, as well as IT, in a Chinese population. Anatomic dissections of the head and neck were carried out bilaterally after student-performed neck dissections during a topographic anatomy course. The types of AB, PB, and IT were recorded to characterize and classify each digastric muscle. The incidence of AB variation was 21.05%. IT type Ⅰ and IT type Ⅱ accounted for 31.25% and 68.75%, respectively. The gross anatomy of the digastric was dominated by the arrangement of AB type I, IT type Ⅱ, and PB type I (63.16%). In addition, 2 rare AB variations were identified. To the best of our knowledge, this is the first report describing individual digastric arrangements and anatomically defining the normal digastric arrangement in the Chinese population. Careful consideration of the variant and anomaly of the digastric is critical for both surgeons and radiologists to provide accurate diagnostic and therapeutic procedures.