[TA] muscle of suboccipital triangle; origin, from posterior tubercle of atlas; insertion, medial third of inferior nuchal line of occipital bone; action, rotates head and draws it backward; nerve supply, dorsal branch of first cervical (suboccipital).suboccipital muscles. SYN: musculus rectus capitis posterior minor [TA], musculus rectus capitis posticus minor, smaller posterior rectus muscle of head.