Where Are Lymph Nodes Located in Your Rib Cage?

Lymph nodes sit in several distinct clusters throughout the rib cage, concentrated mainly along the breastbone, in the central compartment between the lungs (the mediastinum), and at the points where the major airways enter the lungs. These nodes are not randomly scattered; they follow the paths of blood vessels, airways, and lymphatic channels in predictable patterns that doctors rely on when staging cancers, diagnosing infections, and interpreting imaging. Understanding where these clusters sit helps make sense of why a CT report might mention “subcarinal lymphadenopathy” or why a breast surgeon cares about nodes you have never felt from the outside.

The Internal Thoracic Chain Along the Breastbone

One of the most clinically important groups runs just behind the breastbone (sternum), flanking the internal mammary artery and veins. These are the internal thoracic nodes, also called internal mammary nodes. They sit in the parasternal intercostal spaces, which are the gaps between the ribs right next to the sternum. A cadaver study found that the third intercostal space is the most likely to contain at least one of these nodes, with rates around 86% on the right side and 76% on the left. The second intercostal space had nodes about 69–74% of the time, and the fourth space had them less consistently, around 33–48% depending on the side.¹ The nodes tend to sit laterally (toward the outside of the body) in the upper intercostal spaces and shift medially (toward the midline) as you move downward.

These nodes are small and tucked behind bone and cartilage, so you cannot feel them from the surface. Imaging studies using breast MRI have confirmed that internal mammary nodes show up more often on the left side and are most commonly visible at the second and third intercostal spaces, medial to the internal mammary vessels.² Most rib cartilage spaces below the fourth do not contain nodes at all, so the chain is concentrated in the upper part of the chest.

Mediastinal Nodes in the Central Chest

The mediastinum is the space between your two lungs, stretching from the breastbone in front to the spine in back. It houses the heart, the great blood vessels, the trachea (windpipe), and the esophagus. Lymph nodes cluster around all of these structures. Doctors divide the mediastinum into numbered “stations” to communicate precisely about which nodes they are referring to, using a system called the IASLC map. Stations 1 through 9 correspond to mediastinal node groups, while stations 10 through 14 represent nodes farther out toward and within the lungs.³

Here is where the key mediastinal groups sit:

• Paratracheal nodes: These run alongside the trachea, from the lower neck into the upper chest. Upper paratracheal nodes (stations 1 and 2) sit near where the trachea enters the chest. Lower paratracheal nodes (station 4) are found closer to where the trachea splits into the two main bronchi. Right-sided paratracheal nodes tend to be larger than left-sided ones.
• Subcarinal nodes: Station 7 sits directly beneath the carina, the point where the trachea forks into the left and right main bronchi. These are among the largest normal mediastinal nodes and are a common site of enlargement in both cancer and inflammatory diseases.
• Aortopulmonary window nodes: Station 5 sits in the angle between the aortic arch and the left pulmonary artery. Station 6 (pre-aortic) lies in front of the aorta. Both are particularly relevant to left-sided lung tumors.
• Paraesophageal and pulmonary ligament nodes: Stations 8 and 9 lie along the esophagus and within the pulmonary ligaments near the lower part of the chest. These are harder to reach with some biopsy tools but accessible with others.

A CT study of patients without known disease found that the largest normal mediastinal nodes tend to appear in the subcarinal and right tracheobronchial regions, and suggested that a short-axis measurement of 1.0 cm is a reasonable upper limit for a normal mediastinal node on cross-sectional imaging.⁴ That 1-cm threshold is still widely used as a screening cutoff, though it is imperfect. Some normal nodes exceed a centimeter, and some cancerous nodes are smaller.

Hilar and Bronchopulmonary Nodes

Moving outward from the mediastinum, another cluster of nodes appears at the lung hilum, the region where the bronchi, pulmonary arteries, and pulmonary veins enter and exit each lung. Hilar nodes (station 10) sit at this root of the lung and filter lymph draining from deeper within the lung tissue. Just beyond them, along the lobar and segmental bronchi, are the interlobar (station 11), lobar (station 12), segmental (station 13), and subsegmental (station 14) nodes.³

These peripheral lung nodes are the first stop for fluid draining from the lung tissue itself. When an infection like pneumonia or tuberculosis settles in one part of the lung, hilar nodes on that side often swell first. Cancer that begins in the lung typically spreads to these nodes before reaching the more central mediastinal stations, which is why surgical staging distinguishes carefully between hilar involvement (N1 disease) and mediastinal involvement (N2 or N3), since the distinction changes treatment.

Why the Internal Thoracic Chain Matters for Breast Cancer

Most people associate breast cancer with lymph nodes in the armpit, and for good reason: the axillary nodes receive the majority of breast lymphatic drainage. But roughly 15–25% of the breast’s lymphatic flow passes instead through the internal thoracic chain inside the rib cage.⁵ This drainage pathway runs along the internal mammary artery and veins in the parasternal intercostal spaces, and involvement of these nodes can negatively affect prognosis.⁶

The deep structures of the breast, particularly the inner quadrants, are the areas most likely to drain toward the breastbone rather than the armpit. The internal thoracic basin accounts for up to a quarter of breast lymphatic drainage from these deeper tissues.⁷ This is clinically significant because a breast tumor could spread to internal mammary nodes even when the axillary nodes are clean, potentially upstaging the disease and changing treatment decisions about radiation fields. Modern imaging and sentinel node techniques have made it more common to evaluate these nodes, though routine surgical biopsy of internal mammary nodes remains debated.

Conditions That Cause Chest Lymph Node Enlargement

Enlarged lymph nodes inside the rib cage rarely cause symptoms you can feel. Unlike neck or armpit nodes, you cannot palpate them through the chest wall. They typically show up incidentally on imaging or become large enough to compress nearby structures. One study found that chest-related symptoms were actually absent in the majority of patients with mediastinal lymphadenopathy, whether the cause was tuberculosis, a benite condition like anthracosis, or cancer.⁸ When symptoms do appear, they tend to involve cough, a sense of pressure in the chest, or difficulty swallowing if nodes press against the esophagus.

Infections

Tuberculosis is one of the classic causes of mediastinal lymph node enlargement worldwide. The bacteria spread to lymph nodes and trigger granuloma formation, which disrupts and can eventually replace the normal structure of the node.⁹ In adults, mediastinal TB can present without the classic lung findings, sometimes appearing only as enlarged mediastinal nodes on imaging, which can look worryingly similar to lymphoma or sarcoidosis.¹⁰ Fungal infections like histoplasmosis and coccidioidomycosis also commonly cause hilar and mediastinal node swelling, especially in geographic regions where these organisms are endemic.

Sarcoidosis

Sarcoidosis is a systemic inflammatory disease that shows a striking preference for the chest. About 90% of patients have intrathoracic involvement, and the hallmark pattern is symmetrical bilateral hilar lymph node enlargement.¹¹ More than 85% of sarcoidosis patients develop lymph node enlargement at some point during their disease.¹² The symmetry of the swelling is a useful diagnostic clue. Cancers and infections tend to enlarge nodes on one side or in an asymmetric pattern. When a radiologist sees bilateral hilar adenopathy in a young or middle-aged adult, sarcoidosis moves to the top of the differential diagnosis list.

Cancers

Lung cancer is the most common malignancy to involve mediastinal lymph nodes, but lymphomas, esophageal cancer, and metastases from distant cancers (breast, kidney, melanoma) can all cause enlargement. The pattern of node involvement helps doctors figure out where the disease started and how far it has spread. Lung cancer staging, in particular, hinges on which specific mediastinal stations contain tumor cells, because this determines whether a patient is a candidate for surgery or needs chemotherapy and radiation instead.

How Doctors Evaluate These Nodes

Because chest lymph nodes are invisible from the outside and cannot be felt during a physical exam, imaging and specialized biopsy techniques are the only ways to evaluate them.

Imaging

A standard chest CT scan is the initial tool. It shows the size, shape, and location of lymph nodes throughout the mediastinum, hila, and internal thoracic chain. The IASLC lymph node map provides radiologists and oncologists with a shared vocabulary for describing exactly where an abnormal node sits.¹³ However, CT can only measure size; it cannot reliably distinguish a reactive node swollen from an infection from one containing cancer cells.

PET-CT adds metabolic information. Nodes that take up more of the radioactive glucose tracer are more suspicious for malignancy. One study found that using PET-CT with a standard tracer-uptake cutoff gave about 93% sensitivity for detecting malignant mediastinal nodes but only about 40% specificity, meaning many benign nodes also light up. By raising the cutoff threshold, the researchers improved specificity to around 70% while maintaining sensitivity near 87%.¹⁴ Infections and inflammatory conditions like sarcoidosis can also cause nodes to glow brightly on PET, which is why imaging alone rarely settles the diagnosis.

Minimally Invasive Biopsy

When imaging raises a red flag, doctors often need a tissue sample. The dominant technique today is endobronchial ultrasound-guided transbronchial needle aspiration, known as EBUS-TBNA. A thin ultrasound probe is threaded through the airway, and a needle is passed through the bronchial wall directly into a lymph node under real-time guidance. This approach can reach paratracheal nodes (stations 2 and 4), subcarinal nodes (station 7), and hilar nodes (stations 10–12).¹⁵ A complementary technique using an ultrasound scope through the esophagus (EUS-FNA) can access the subcarinal, paraesophageal, and pulmonary ligament stations that are harder to reach from the airway side.

These procedures have high accuracy. One prospective multicenter study of systematic mediastinal staging with EBUS-TBNA reported sensitivity and specificity both around 90%, with overall diagnostic accuracy of 90%.¹⁶ An earlier single-center study found even higher numbers, with sensitivity of about 96% and specificity of 100%.¹⁷ These procedures do not require general anesthesia in most cases and are far less invasive than older surgical approaches like mediastinoscopy.¹⁸

Lymph Node Removal During Surgery

When a patient undergoes surgery for lung cancer, the surgeon does not simply remove the tumor. Complete mediastinal lymph node dissection means systematically removing entire node stations on the same side as the tumor. For a tumor on the right side, that typically includes stations 2R, 3, 4R, 7, 8, and 9. For a left-sided tumor, the dissected stations shift to include stations 5, 6, 7, 8, and 9.¹⁹ This thoroughness serves two purposes: it provides the most accurate picture of how far cancer has spread, and it removes microscopic disease that might otherwise grow back.

The difference between right-sided and left-sided dissections reflects real anatomy. The right paratracheal region has more accessible node tissue, while the left side has the aortopulmonary window and pre-aortic nodes that lie in the shadow of the great vessels. Surgeons performing video-assisted thoracoscopic surgery (VATS) or robotic procedures have developed techniques to dissect these stations as thoroughly as they would during open surgery, though the technical demands differ by location.

Rare Anatomical Variants

The lymphatic system is more variable between individuals than the blood-vessel system. Some people have more nodes in a given station than others, and the drainage pathways are not perfectly symmetrical. Occasionally, congenital malformations of the lymphatic system occur within the chest wall. Lymphangioma, for instance, is a benign malformation in which lymphatic vessels proliferate abnormally. While lymphangiomas typically appear in the neck or armpit, they can rarely involve the chest wall.²⁰ These are developmental anomalies rather than cancers, and they are usually treated with surgical excision when they cause symptoms or grow large enough to compress other structures.

Normal variation also matters in practical medicine. The cadaver study of internal thoracic nodes found that the distribution of nodes across intercostal spaces was not uniform from person to person, and many rib cartilage spaces contained no nodes at all.¹ For sentinel node biopsy in breast cancer, that variability means surgeons cannot assume a node will be in a particular space. They need lymphoscintigraphy or tracer injection to map the actual drainage path in each patient, because anatomy textbook diagrams represent averages, not guarantees.

How Mediastinal Node Maps Evolved

The numbered station system that doctors use today did not always exist in its current form. Older classification systems, including the Naruke map popular in Japan and the Mountain-Dresler modification used in North America, described the same anatomical regions but drew the boundaries slightly differently. Two radiologists reading the same scan could assign a borderline node to different stations depending on which map they had learned. The IASLC map, published as part of the seventh edition of the TNM staging system, was created specifically to reconcile these discrepancies and establish a single international standard.³ The practical difference for patients is that a stage determined at one hospital now means the same thing at another, regardless of country, which was not always the case before.

Radiologists now use CT and PET-CT to map nodes against the IASLC stations as a routine part of lung cancer workup.²¹ The map also helps interventional pulmonologists plan which biopsy route to use. Nodes in stations 2, 4, and 7 are accessible through the airway with EBUS, while stations 8 and 9 require the esophageal approach. Knowing the station number instantly tells the proceduralist what tool to reach for.