The digastric muscle consists of the anterior belly and the posterior belly connecting the mandible, hyoid bone and temporal bone. Its unique morphology, structure and variations have drawn genuine interests in this muscle from anatomists, scientists and physicians for a long time, and the variations of the digastric muscle have been documented since the 18th century. As the usage of computed tomography and magnetic resonance imaging in the neck has become ever increasing, recognizing the variations of the digastric muscle can be a great value since it helps physicians to make better treatment plans and avoid unnecessary invasive procedures in the neck. Although the variations of the digastric muscle do not necessarily cause clinical symptoms, they still have important clinical applications. This article discusses the anatomy, embryology, descriptions of the morphological variations and clinical significance of the digastric muscle.