Final answer:
The serrates posterior muscles support the rib cage, aiding in inhalation by elevating the ribs. Other muscles such as the external intercostal muscles and the erector spinae play key roles in breathing and postural support respectively, while true ribs attach directly to the sternum.
Step-by-step explanation:
The serrates posterior muscles are part of the group of muscles associated with the thoracic cage. When considering their action, the most accurate option from the list provided would be that they support the rib cage. These muscles assist in the mechanical aspect of breathing by helping to elevate the ribs during inhalation, which increases the volume of the thoracic cavity.
Regarding related muscle functions, the contraction of the external intercostal muscles causes elevation of the rib cage and expands the thoracic cavity, aiding in inhalation. The function of the erector spinae is to provide postural support and aid in the extension and rotation of the vertebral column. Lastly, true ribs are those directly attached to the sternum via their costal cartilage, which is represented by ribs 1-7.