The jugular vein notch is composed of the upper edge of the sternal stalk of the upper thorax, the 1st rib and the 1st thoracic vertebral body, i.e., the sternum (located in the middle of the anterior thoracic wall, long and flat, divided into 3 parts: sternal stalk, sternal body, and saber) in which the upper edge of the sternal stalk is concave, called the jugular vein notch, flat against the lower edge of the 2nd thoracic vertebra. The purpose is to explore the age-related changes in the inclination of the upper thoracic opening and its interrelationship with respiratory function, that is, the height of the upper sternal border gradually decreases as the body develops, and the lower the upper sternal border, the greater the lung capacity.