Origin: fascia of pectoralis
Insertion: mandible, skin of lower face
Action: pulls lower lip down (as in frowning), depresses mandible (opening mouth as when chewing or surprised), and tenses skin of the neck (as when gritting teeth)
Bone of Insertion: mandible
Insertion: mandible, skin of lower face
Action: pulls lower lip down (as in frowning), depresses mandible (opening mouth as when chewing or surprised), and tenses skin of the neck (as when gritting teeth)
Bone of Insertion: mandible