In this video I will identify the muscles that position the pectoral girdle and list the origin, insertion and action of major muscles that position the pectoral girdle. Here we can see the trapezius is a large triangular shaped superficial muscle on the posterior of the cervical and thoracic regions. The trapezius has the action of elevating and depressing the pectoral girdle depending on if the superior or inferior regions of the trapezius are contracting. The two major regions, the superior and inferior regions, the trapezius will have opposite actions whereas if the entire trapezius muscle contracts including the middle region, the trapezius will have the action of retracting the scapula and drawing it towards the midline. The trapezius is a little smaller and more superior than the rhomboid major but the rhomboid muscles will have the action of retracting the scapula and drawing the scapula towards the midline. The trapezius has its origin from the external occipital protuberance as well as along the spinous processes of the cervical and thoracic vertebrae. The insertion of the trapezius is on the scapula along the spine of the scapula as well as the acromion of the scapula and also onto the lateral end of the clavicle. The action of trapezius is to elevate or depress the pectoral girdle. The rhomboid major has its origin from the spinous processes of thoracic vertebrae, specifically T2 through T5 and its insertion is the medial border of the scapula just inferior to the root of the scapula. The action of the rhomboid major is to retract the scapula. Here from an anterior view we can see the pectoralis minor, a major muscle that is involved in protracting the scapula as well as the serratus anterior. Another muscle group that is involved in protracting the scapula. So pectoralis minor has its origin from ribs 3 through 5, although there is some variation. Occasionally pectoralis minor has its origin on rib 2 through 4. But as we see in the illustration here the origin is ribs 3 through 5. The insertion of pectoralis minor is the corquate process of the scapula and that provides the action of protracting the scapula.