Anterior view, anatomical position

The sternal angle (angle of Louis) is the name of the manubriosternal joint.  It is a fibrocartilage joint that allows for some movement acting like a hinge so that the body can move anteriorly during deep inspiration.  It is also a landmark used to identify the boundary between the superior and inferior mediastinal cavities.  It is at the level of the intervertebral disc between thoracic vertebrae 4 and 5.  This is the superior extent of the heart as well as the inferior end of the trachea when a person is supine.

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