Lung Apex

The apex of the lung is the rounded superior extremity of each lung. Unlike most of the lungs, which are contained within the thoracic cavity, the apex extends superiorly through the superior thoracic aperture into the root of the neck.

From a surface anatomy perspective, the lung apex projects approximately 2 to 3 cm above the medial third of the clavicle. This means that lung and pleura are present superior to the level of the first rib and clavicle, an important relationship during examination, trauma assessment, and procedures near the root of the neck.

The apex is covered by the cervical pleura, also called the cupula of the pleura, and reinforced externally by the suprapleural membrane.

Location

The lung apex occupies the superior-most part of the lung and extends into the lower neck through the superior thoracic aperture.

It lies deep to structures at the root of the neck and superior to the level of the first rib.

Surface Projection

The apex can be projected onto the body surface as extending approximately 2 to 3 cm superior to the medial third of the clavicle.

The exact level varies with body habitus, respiratory phase, posture, and individual thoracic anatomy.

Relationship to the Clavicle

The clavicle is the most useful external landmark for estimating the position of the lung apex.

The apical lung tissue lies deep to the supraclavicular region and extends slightly above the medial portion of the clavicle.

Supraclavicular Region

The supraclavicular region overlies the superior part of the thoracic inlet and the projecting lung apex.

Because the lung extends into this region, examination of the lungs includes auscultation above the clavicles.

Superior Thoracic Aperture

The lung apex passes through the superior thoracic aperture, commonly called the thoracic inlet.

This opening connects the thoracic cavity with the root of the neck.

Boundaries of the Superior Thoracic Aperture

Boundary	Structure
Posterior	Body of T1 vertebra
Lateral	First ribs and their costal cartilages
Anterior	Superior border of the manubrium

First Rib Relationship

The first rib forms an important boundary of the superior thoracic aperture.

The apex of the lung rises superior to the first rib into the cervical region.

Cervical Pleura

The portion of parietal pleura extending into the neck over the lung apex is called the cervical pleura.

It forms a dome over the superior surface of the lung and is also known as the pleural cupula.

Pleural Cupula

The cupula extends above the first rib and accompanies the lung apex into the root of the neck.

It is important to distinguish the pleural projection from the lung itself because the pleura forms the enclosing sac around the apical lung.

Suprapleural Membrane

The cervical pleura is reinforced by the suprapleural membrane, also called Sibson's fascia.

This fibrous membrane extends across the superior thoracic aperture and helps support the cervical pleura against pressure changes generated during respiration.

Sibson's Fascia

Sibson's fascia is attached to structures including the first rib and the transverse process of the seventh cervical vertebra.

It forms a protective fascial roof over the pleural cupula.

Relationship to the Subclavian Artery

The subclavian artery arches across the superior aspect of the pleural dome near the lung apex.

This close relationship is important in the anatomy of the thoracic inlet and root of the neck.

Relationship to the Subclavian Vein

The subclavian vein lies anterior to the anterior scalene muscle and is also closely related to the first rib and pleural region.

Its proximity to the cervical pleura is important during central venous access.

Relationship to the Brachial Plexus

The brachial plexus passes through the root of the neck superior and lateral to the lung apex.

The inferior trunk of the plexus is especially relevant to lesions arising near the superior pulmonary sulcus.

Relationship to the Sympathetic Trunk

Sympathetic structures lie close to the posterior aspect of the apical thoracic region.

This relationship becomes clinically important when disease at the lung apex extends into neighboring neural structures.

Relationship to the Scalenes

The scalene muscles occupy the lateral root of the neck near the superior thoracic aperture.

The first rib, subclavian vessels, brachial plexus, cervical pleura, and lung apex all have important relationships within this compact region.

Apical Surface

The apex is rounded and conforms to the pleural dome surrounding it.

Its surface may show impressions related to neighboring structures, particularly major vessels in the superior thoracic region.

Right and Left Lung Apices

Both lungs extend into the root of the neck, but their neighboring mediastinal and vascular relationships are not identical.

The right apex is related to structures associated with the right subclavian and brachiocephalic region, while the left apex has relationships with vessels on the left side of the superior mediastinum and root of the neck.

Respiratory Movement

The lungs change volume during respiration, but the apex is relatively constrained by the surrounding pleura, fascia, thoracic inlet, and cervical structures.

Its exact surface position can nevertheless vary slightly with respiratory phase.

Auscultation of the Lung Apex

The apical portions of the lungs should be assessed by placing the stethoscope in the supraclavicular regions.

This allows breath sounds from the superior lung fields to be compared between the right and left sides.

Anterior Auscultation

Anteriorly, the upper lung fields can be examined above and below the clavicles.

Comparison should be made at corresponding levels on both sides.

Posterior Auscultation

Posteriorly, the upper lobes are assessed over the upper thoracic and scapular regions.

The lung apex itself is most directly represented near the root of the neck rather than over the lower posterior thorax.

Percussion

Percussion over the supraclavicular region can contribute to examination of the apical lung.

Findings must be interpreted in the context of the surrounding muscles, clavicle, and other tissues that influence transmitted sound.

Upper Lobe Relationship

The apex belongs to the upper lobe of each lung.

On the right it forms part of the right superior lobe, and on the left it forms part of the left superior lobe.

Lung Apex Versus Pleural Apex

Feature	Lung Apex	Cervical Pleura
Structure	Superior pulmonary tissue	Parietal pleural covering
Location	Root of neck above first rib	Forms dome around lung apex
Support	Contained within pleural sac	Reinforced by suprapleural membrane
Surface landmark	Approximately 2 to 3 cm above medial clavicle	Also extends into supraclavicular region

Clinical Significance

Apical Lung Examination

The extension of the lung above the clavicle means that complete respiratory examination includes the supraclavicular regions.

Breath sounds should be compared bilaterally because apical disease may otherwise be less apparent on routine lower chest examination.

Pneumothorax

Because cervical pleura extends into the root of the neck, penetrating injury in the supraclavicular region can potentially enter the pleural cavity and produce a pneumothorax.

The clavicle does not completely protect the superior pleural dome.

Central Venous Access

The close relationship of the subclavian vein to the cervical pleura is clinically important during subclavian venous catheterization.

Unintended pleural injury is a recognized complication of procedures in this region.

Superior Sulcus Tumor

A tumor arising near the apex of the lung may extend into structures of the thoracic inlet and root of the neck.

Such lesions are often referred to as superior sulcus tumors or Pancoast tumors.

Brachial Plexus Involvement

Because the inferior portion of the brachial plexus lies close to the lung apex, an apical tumor can involve neural structures and produce symptoms in the upper limb.

Sympathetic Involvement

Disease extending from the lung apex into the cervical sympathetic pathway can affect sympathetic innervation of the head and neck.

This anatomical relationship explains why some apical lesions can produce characteristic neurological findings.

Apical Pleural Thickening

Imaging may demonstrate thickening or scarring near the lung apex.

Interpretation depends on the pattern, extent, clinical context, and comparison with prior imaging.

Tuberculosis

Pulmonary tuberculosis has historically been associated with upper lobe and apical pulmonary involvement in post-primary disease.

Knowledge of the apical surface projection is therefore relevant when correlating physical and radiological findings.

Chest Imaging

The lung apices are routinely assessed on chest radiographs and cross-sectional imaging.

Careful evaluation is important because the clavicles and other structures can overlap the apical lung fields on frontal radiographs.

Trauma

Trauma to the lower neck or supraclavicular region can potentially affect the apical lung, pleura, subclavian vessels, or brachial plexus.

The close concentration of these structures makes accurate anatomical localization important.

Surface Landmark Variability

The commonly cited projection of 2 to 3 cm above the medial clavicle is an approximation.

Thoracic shape, neck length, posture, respiration, and individual anatomy can alter the precise relationship.

Nearby Surface Landmarks

Landmark	Relationship to Lung Apex
Clavicle	Apex projects above medial third
First rib	Apex extends superior to it
Supraclavicular fossa	Overlies apical lung and cervical pleura
Manubrium	Forms anterior boundary of superior thoracic aperture
T1 vertebra	Forms posterior boundary of superior thoracic aperture

Key Surface Anatomy Features

Feature	Key Point
Structure	Rounded superior extremity of lung
Region	Superior thoracic aperture and root of neck
Clavicular projection	Approximately 2 to 3 cm above medial third of clavicle
Pleural covering	Cervical pleura or pleural cupula
Fascial reinforcement	Suprapleural membrane
Important vessel relationship	Subclavian vessels
Important nerve relationship	Brachial plexus
Lobar location	Superior lobe
Examination region	Supraclavicular area
Clinical importance	Apical disease, pneumothorax risk and superior sulcus tumors

Anatomical Importance

The lung apex is an important landmark because it demonstrates that the lungs extend beyond the apparent boundaries of the thoracic cage. The apex rises through the superior thoracic aperture into the root of the neck and projects approximately 2 to 3 cm above the medial portion of the clavicle.

This superior extension places the apical lung and cervical pleura close to the subclavian vessels, brachial plexus, scalene muscles, and sympathetic structures. The pleural dome surrounding the apex is reinforced by the suprapleural membrane but remains clinically relevant during trauma and procedures in the supraclavicular region.

Knowledge of this surface projection is also important during respiratory examination because the apical lung fields are auscultated above the clavicles. The region has particular clinical significance in pneumothorax, apical pulmonary disease, central venous procedures, and tumors arising near the superior pulmonary sulcus.