 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, and 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. Deep to the trapezius here we can see the rhomboid muscles, rhomboid minor 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. And so 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 acromial end of the clavicle. And so the action of trapezius is to elevate or depress the pectoral girdle. 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 scapular spine. 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's involved in protracting the scapula, as well as the serratus anterior, another muscle group that's 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 coracoid process of the scapula that provides the action of protracting the scapula.