Skeletal Structures:
* Manubrium and Body of the Sternum: The sternal angle marks the junction of these two parts of the sternum.
* Second Costal Cartilage: The sternal angle is at the level of the articulation of the second costal cartilage with the sternum.
* Second Rib: The second rib articulates with the second costal cartilage, thus the sternal angle also corresponds to the level of the second rib.
Other Anatomical Structures:
* Trachea: The trachea lies directly behind the sternal angle.
* Aortic Arch: The aortic arch passes just behind the sternal angle, giving rise to the brachiocephalic trunk, left common carotid artery, and left subclavian artery.
* Superior Vena Cava: The superior vena cava lies to the right of the ascending aorta and enters the right atrium at the level of the third costal cartilage, just above the sternal angle.
* Thymus Gland: The thymus gland lies in the mediastinum, behind the sternum, and extends from the sternal angle to the fourth costal cartilage.
* Bifurcation of the Trachea: The trachea divides into the right and left main bronchi at the level of the sternal angle.
* Pulmonary Arteries: The right and left pulmonary arteries originate from the pulmonary trunk at the level of the sternal angle and course towards the lungs.
* Pulmonary Veins: The pulmonary veins drain oxygenated blood from the lungs and return it to the left atrium, passing through the mediastinum near the sternal angle.
Clinical Importance:
The sternal angle is a crucial landmark in clinical practice, providing a reference point for:
* Counting Ribs: The sternal angle marks the level of the second rib, helping to locate other ribs.
* Locating the Trachea: The trachea is easily palpable behind the sternal angle.
* Auscultating Heart Sounds: The sternal angle is used as a reference point for listening to heart sounds.
* Assessing Lung Expansion: The sternal angle helps to assess lung expansion during respiration.
* Performing Procedures: The sternal angle serves as a landmark for procedures like central line insertion.
Understanding the structures at the level of the sternal angle is essential for healthcare professionals as it provides crucial anatomical landmarks for various clinical procedures and assessments.
