Superior Sternum: Anatomy, Function, And Clinical Significance

The superior portion of the sternum, known as the manubrium sterni, is distinguishable by its jugular notch that articulates with the clavicles. The suprasternal notch, a prominent V-shaped landmark, is formed between the manubrium and clavicles. Clinically, the superior sternum serves as a reference point for medical examinations and surgical procedures. It supports and protects thoracic organs and contributes to rib cage stability. Anatomically, the sternocleidomastoid muscles and mediastinum are associated with this region.

The Manubrium Sterni: The Keystone of the Chest’s Framework

At the crest of the rib cage, where the human chest takes shape, lies the manubrium sterni, the uppermost segment of the sternum. This vital bone serves as the central pillar, anchoring the delicate framework of the ribcage and safeguarding the precious organs within.

Anatomical Features: A Complex Structure

The manubrium sterni is a broad, flat bone with several distinctive anatomical features:

• Jugular Notch: A deep cleft at its superior border, the jugular notch allows the passage of the jugular veins and suprasternal notch vessels.
• Clavicular Articulations: The manubrium articulates with both clavicles, forming the sternoclavicular joints. These joints allow for a wide range of movement in the shoulders and arms.
• Costal Cartilages: The manubrium connects to the first and second pairs of ribs via costal cartilages. These flexible connections provide stability to the ribcage and allow for respiratory movements.

Suprasternal Notch: A V-Shaped Landmark

At the manubrium sterni’s superior end lies the suprasternal notch, a V-shaped indentation. This notch is formed by the meeting of the manubrium with the medial ends of the clavicles. It serves as a significant anatomical landmark, demarcating the superior boundary of the sternum and indicating the level of the second thoracic vertebra.

Clinical Significance: A Reference Point for Medical Interventions

The superior portion of the sternum is of immense clinical importance. Medical professionals often use it as a reference point for examinations and surgical procedures:

• Anatomical Localization: The manubrium sterni and suprasternal notch provide surgeons with precise landmarks for localizing structures in the chest, such as the trachea, esophagus, and heart.
• Access to Thoracic Cavity: Through the suprasternal notch, surgeons can gain access to the thoracic cavity to perform procedures like cardiac surgery or lung biopsy.

Structural Importance: A Pillar of Support

The superior sternum plays a crucial role in the structural integrity of the thoracic cage:

• Thoracic Organ Protection: The manubrium sterni forms part of the bony framework that encloses and protects vital thoracic organs, including the heart, lungs, and major blood vessels.
• Rib Cage Stability: The manubrium’s strong connections to the ribs provide stability and prevent the ribcage from collapsing or buckling during forceful movements.

Suprasternal Notch: A V-Shaped Landmark at the Superior End

Nestled at the very top of our chest, where the collarbones (clavicles) meet, lies a V-shaped indentation known as the suprasternal notch. This notch, formed by the articulation of the uppermost segment of the sternum (manubrium sterni) with the clavicles, serves as a prominent anatomical landmark in the supraclavicular fossa (the hollow space above the collarbone).

The suprasternal notch is a crucial reference point for medical professionals, guiding them in locating the superior portion of the sternum. During physical examinations, the notch is often palpated (felt) to identify the manubrium sterni and assess any abnormalities.

Moreover, the suprasternal notch plays a pivotal role in surgical procedures, serving as a landmark for tracheostomies (creating an opening in the trachea through the neck) and thoracic surgeries.

In the realm of thoracic anatomy, the superior portion of the sternum, including the suprasternal notch, provides structural support for the rib cage. The manubrium sterni articulates with the first pair of ribs, while the suprasternal notch lies just above the jugular notch, where the sternocleidomastoid muscles (large muscles in the neck) attach. Together, these elements contribute to the stability and function of the chest cavity, protecting the vital organs within.

Clinical Significance of the Superior Sternum

Identifying the superior portion of the sternum, encompassing the manubrium sterni and suprasternal notch, holds immense clinical significance in medical examinations and surgical procedures.

The manubrium sterni serves as a crucial anatomical landmark, easily palpable through the skin. Its prominent articulation with the clavicles forms the sternoclavicular joints, vital for upper limb movement. Moreover, the costal cartilage of the first and second ribs attaches to the manubrium, contributing to the stability of the rib cage.

The suprasternal notch is an equally important reference point at the superior end of the manubrium. It marks the midline of the upper chest and lies just below the skin’s surface. This notch is bounded laterally by the clavicles and medially by the prominent sternocleidomastoid muscles.

During physical examinations, the suprasternal notch is used to locate the cricoid cartilage, which is essential for securing the patient’s airway during intubation. Additionally, the notch serves as a guide for placing the stethoscope to auscultate the heart and lungs.

In surgical procedures, the manubrium sterni and suprasternal notch provide crucial orientation for accessing the thoracic cavity. Median sternotomy, a surgical approach involving incision through the manubrium, allows access to the heart and major blood vessels. The suprasternal notch is also used as a reference point for performing tracheotomy, a surgical procedure to create an airway opening directly into the trachea.

Understanding the anatomy of the superior sternum and its clinical significance is paramount for medical professionals in performing accurate examinations, interpreting imaging studies, and executing surgical interventions effectively.

Role of the Superior Sternum in Thoracic Anatomy

Nestled at the superior end of the sternum, the manubrium sterni plays a crucial role in safeguarding and sustaining the thoracic organs. This bony structure forms the foundation of the rib cage, providing stability and protection for the vital structures within.

The manubrium’s sturdy frame supports the attachment of the first pair of ribs, known as the true ribs. These ribs are directly connected to the sternum, forming a solid base for the rib cage. The remaining ribs articulate with the lateral margins of the sternum through costal cartilage, contributing to the flexibility and expansion of the thoracic cavity during respiration.

Moreover, the superior portion of the sternum plays a pivotal role in protecting the underlying thoracic organs. It acts as a shield, guarding the heart, lungs, and great vessels from external impacts and forces. The manubrium’s prominent position ensures that it bears the brunt of any trauma, minimizing the risk of damage to these delicate structures.

Additionally, the superior sternum participates in the mediastinum’s formation, a central partition that divides the thoracic cavity into two compartments. This septum accommodates the heart, great vessels, trachea, and esophagus. The manubrium’s close association with the mediastinum further enhances the protection of these vital components.

In summary, the superior portion of the sternum is an indispensable anatomical structure that supports, protects, and stabilizes the thoracic organs. It serves as the foundation for the rib cage, provides anchorage for the ribs, and acts as a shield against external forces. Its role in the formation of the mediastinum further underscores its critical importance in maintaining the integrity and functionality of the thoracic cavity.

Additional Anatomical Considerations

• Discuss any additional relevant anatomical structures associated with the superior portion of the sternum, such as the sternocleidomastoid muscles and the mediastinum.

Additional Anatomical Considerations

The superior portion of the sternum is also associated with several other relevant anatomical structures that play significant roles in the body’s anatomy and function. These structures include:

• Sternocleidomastoid muscles: These paired muscles originate from the manubrium sterni and clavicle and insert into the mastoid process of the temporal bone. They are responsible for rotating the head to the opposite side and flexing the neck.

• Mediastinum: The mediastinum is a compartment within the thoracic cavity that separates the left and right lungs. It contains the heart, great vessels, esophagus, trachea, and other important structures. The superior portion of the sternum forms the anterior boundary of the mediastinum.

Understanding the anatomical relationships of the superior sternum with these structures is crucial for medical examinations and surgical procedures. The jugular notch and suprasternal notch serve as landmarks for locating the superior portion of the sternum, which in turn helps surgeons access the mediastinum and perform interventions on the heart and other thoracic organs.

Moreover, the superior sternum plays a role in stabilizing the rib cage and protecting the thoracic organs from external forces. Its strong cartilaginous connections with the clavicles and ribs contribute to the rigidity and stability of the chest wall, ensuring proper respiratory function and protection of the vital organs within.