extensor indicis synergist and antagonist It's a ''two-headed'' muscle, meaning it has two origin sites and one insertion site. Sternocleidomastoid Muscle, Its Attachments and Actions have the mm. Action: retracts and rotates scapula. Frequent headaches, ptosis, … Muscles are attached to bones by tendons. When both muscles contract, the head is bent toward the chest. i think it's the rectus capi lateralus. Muscles transfer force to bones through tendons. What Are Muscle Agonists, Antagonists, And Synergists? | 3DML This question focuses on Learning Objective 4: … Muscles contract to move our bones by pulling on them. Origin: transverse processes of C 1 - C 4. What is the antagonist muscle to the sternocleidomastoid