*In [[Avian Respiration - Anatomy & Physiology|'''avian]] species''' the trachea is composed of tightly stacked rings of [[Bones and Cartilage - Anatomy & Physiology#Types of Cartilage|cartilage]], which are complete with no dorsal space. They overlap considerably. | *In [[Avian Respiration - Anatomy & Physiology|'''avian]] species''' the trachea is composed of tightly stacked rings of [[Bones and Cartilage - Anatomy & Physiology#Types of Cartilage|cartilage]], which are complete with no dorsal space. They overlap considerably. |