digastric muscle
Concise Oxford English Dictionary © 2008 Oxford University Press:
digastric muscle /dʌɪˈgastrɪk/
▶noun Anatomy each of a pair of muscles which run under the jaw and act to open it.
– origin C17: from mod. L. digastricus, from di- ‘twice’ + Gk gastēr ‘belly’ (because the muscle has two fleshy parts or ‘bellies’ connected by a tendon).
'digastric muscle' also found in these Oxford entries:

