the second pair of ribs
The sternomanubrial junction is where the manubrium (top part of the sternum) meets the body (sternum). It plays a role in connecting the sternum to the clavicles and first rib. It is an important landmark in the chest for medical examinations and procedures.
A protractor will indicate an angle that has to be made.
The costal angle is the angle beneath the the sternum. It is created by the costal cartilage that joins what are called the false ribs, the ones tha6t do not directly attach to the sternum via their own cartilage, but attach directly and indirectly to the cartilage of the 7th rib. This angle is created because these false ribs get shorter as they go down. Since they are connected by the descending costal cartilage which travels laterally and inferiorly from the sternum, it creates the angle known as the costal angle.
at the center of sternum
With a small square in its corner
Locate the middle of the sternum. This is where your hand location should be for an adult or child. For an infant, it will be on the sternum, 1 finger below the nipple line.
"Retrosternal" refers to the area located behind the breastbone (sternum). It is often used to describe the location of pain, discomfort, or pressure felt in the chest.
The manubrium is united to the body of the sternum either by an amphiarthrodial joint-a piece of fibrocartilage connecting the segments-or by a diarthrodial joint, in which the articular surface of each bone is clothed with a lamina of cartilage.
I
The square drawn in a right angle simply is to indicate that the angle is, indeed, 90 degrees.
It is the angle at which the manibrium and sternum meet/articulate. It is an anatomical landmark for finding the second rib, approx. area of the carina