The sternum is composed of seven bones, which are not created in the form of one bone, for the sake of the same usefulness which has been spoken of elsewhere, and also for the purpose that the sternum should be more pliable and more helpful to the expansion of those respiratory organs which surround the chest. Therefore, the bones of the sternum are created soft and connected by cartilages, which help these bones to perform their inherent imperceptible movements, although their joints are motionless. There were seven of them created - according to the number of ribs adjacent to them. Adjacent to the lower part of the sternum is a wide cartilaginous bone, the lower end of which is rounded. It is called dagger-shaped, because it resembles a dagger, and serves as protection for the mouth of the stomach, and also connects the sternum with the soft organs, as a result of which the connection of hard with soft, as we have already said many times, is carried out well.
The collarbone is a bone located on either side of the upper part of the sternum. Due to the curvature of the collarbone, there remains a gap near the throat through which the vessels ascending to the brain and the nerves descending from the brain pass. The bone then bends outward and joins the end of the scapula. The scapula is connected to the collarbone to form the articulation of the forearm.