The lungs are primary organs of the respiratory system, responsible for gas exchange. Each lung has a specific anatomical structure, including a base, borders, and an apex. The apex is simply the highest, most superior point of the lung, where the organ narrows to a rounded tip. Understanding the precise location of this upper region is important for understanding how the lungs interact with the neck and surrounding structures.
What Defines the Apex
The apex is the blunt, superior tip of the upper lobe of each lung, distinguishing it from the broad, concave base that rests on the diaphragm. Its shape is roughly conical, reflecting the overall contour of the lung structure within the chest cavity.
This superior region is shielded by a specialized extension of the parietal pleura, the double-layered membrane that lines the chest wall. This pleural extension is called the cervical pleura, or cupula, and it forms a dome-like covering over the lung’s tip. The cupula separates the lung apex from the structures of the neck, providing a protective barrier.
Positioning Relative to the Neck and Rib Cage
The location of the lung apex is unique because it extends beyond the bony confines of the chest cavity, projecting into the root of the neck. It passes superiorly above the level of the first rib and the clavicle. This means that a portion of the lung sits higher than the upper opening of the bony rib cage.
The lung apex typically reaches about 2.5 to 4 centimeters above the level of the sternal end of the first rib. Its highest point is located roughly at the level of the seventh cervical vertebra (C7), the last bone of the neck before the thoracic spine begins. This superior positioning places the apex directly behind the scalene muscles of the neck.
The subclavian artery, a major blood vessel supplying the arm, arches immediately below the lung apex, creating a slight groove in the lung tissue. This anatomical relationship illustrates why the apex is considered part of the thoracic inlet, the passageway between the chest and the neck.
Clinical Relevance of the Apical Region
The superior position of the lung apex makes it vulnerable to injury and disease processes that affect the neck and shoulder region. Its proximity to the thoracic inlet means that a penetrating injury to the lower neck can puncture the lung apex, potentially leading to a collapsed lung. The apex is related to several important neurovascular structures as they pass into the upper limb.
A tumor that arises in this region is known as a Pancoast tumor, or superior sulcus tumor. These growths frequently invade the surrounding tissues rather than remaining contained within the lung. The tumor can compress the brachial plexus, a bundle of nerves that controls movement and sensation in the shoulder, arm, and hand.
Compression of the brachial plexus by an apical tumor causes symptoms like severe shoulder and arm pain, often radiating down the arm. Pancoast tumors can also affect the sympathetic nerve chain, leading to a constellation of facial symptoms called Horner syndrome. The apex is also a common site for certain infections, such as tuberculosis, which can localize here due to differences in ventilation and blood flow within the upper lung zones.