Final answer:
Girls over age 7 typically exhibit thoracic breathing, which involves the expansion of the rib cage and is facilitated by the contraction of the external intercostal muscles.
Step-by-step explanation:
The respiratory movement typically observed in girls over age 7 is thoracic breathing. This type of breathing involves the rib cage and is characterized by the outward movement of the chest. During inhalation, the contraction of the external intercostal muscles causes the rib cage to expand, increasing the volume of the thoracic cavity. In contrast, diaphragmatic breathing, more common in younger children and boys, involves the diaphragm moving downward during inhalation, playing a major role in respiration. The diaphragm is a dome-shaped muscle that separates the thoracic and abdominal cavities and alters the volume of the thoracic cavity during the breathing process.