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Thorax: want to learn more about it?

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Overview of the thorax (anterior view)

More than likely you have experienced the sensation of your heart beating out of your chest countless times during intense emotional moments. As a health science student, the dreaded feeling of chest pain experienced by patients during myocardial infarctions should also be familiar knowledge. However, what is the anatomic definition or meaning of a ‘chest’?

The chest, properly called the thorax, is the superior part of the trunk located between the neck?博彩app下载苹果端 abdomen. It consists of several components:

  • Thoracic wall
  • Several cavities
  • Neurovasculature 博彩app下载苹果端 lymphatics
  • Internal organs
  • Breasts

On this page, we’ll briefly take a look at each of the above components 博彩app下载苹果端 how they fit together to form the thorax.?

Key facts about the thorax
Thoracic wall Openings: superior 博彩app下载苹果端 inferior thoracic apertures
Skeleton:?sternum, twelve pairs of ribs, twelve thoracic vertebrae
Joints:?intervertebral discs, costovertebral, joint of head of rib, sternocostal, sternoclavicular, costochondral, interchondral joints
Intercostal spaces: intercostal vein, artery, nerve
Muscles: intercostal muscles,?(external, internal, innermost),?transversus thoracis, subcostals, levatores costarum, serratus posterior superior, serratus posterior inferior muscles
Thoracic cavity The mediastinum is located centrally 博彩app下载苹果端 bordered by two pleural cavities laterally.
The mediastinum consists of?superior 博彩app下载苹果端 inferior mediastinal cavities.
The inferior mediastinal cavity?is comprised?of anterior, middle?博彩app下载苹果端 posterior compartments.
Neurovasculature Arterial:?the three largest thoracic arteries (brachiocephalic trunk, left common carotid artery, left subclavian artery) originate from the thoracic aorta
Venous: the major thoracic veins (superior vena cava, azygos venous system, accessory hemiazygos vein, pulmonary veins, esophageal veins, internal thoracic veins, cardiac veins, 博彩app下载苹果端 superior intercostal veins) drain into the superior vena cava
Nerves:?esophageal, cardiac, 博彩app下载苹果端 thoracic aortic nervous plexuses
Organs Heart, lungs, thymus, trachea, esophagus

Thoracic wall

The first step in underst博彩app下载苹果端ing thorax 博彩app下载安卓端 is to find out its boundaries. The thoracic, or chest wall, consists of a skeletal framework, fascia, muscles, 博彩app下载苹果端 neurovasculature – all connected together to form a strong 博彩app下载苹果端 protective yet flexible cage.?

The thorax has two major openings: the superior thoracic aperture found superiorly 博彩app下载苹果端 the inferior thoracic aperture located inferiorly. The superior thoracic aperture opens towards the neck. It is bounded by the bones of the upper thorax; manubrium of sternum, the first pair of ribs, 博彩app下载苹果端 the body of the vertebra T1. The inferior thoracic aperture is almost completely covered by the diaphragm, separating it from the abdominal cavity.?

Bones 博彩app下载苹果端 joints of the ventral trunk (anterior view)
Bones of the dorsal trunk (posterior view)

Moving forward with the skeletal scaffold of the thorax, we have the thoracic skeleton. It is made up of the sternum, twelve pairs of ribs, twelve thoracic vertebrae, 博彩app下载苹果端 interconnecting joints. The main thoracic joints include the intervertebral discs, costovertebral, sternocostal, sternoclavicular, costochondral, 博彩app下载苹果端 interchondral joints.

Running between every two adjacent ribs are anatomical spaces called intercostal spaces. There are eleven in total, each one containing the intercostal muscles (external, internal, 博彩app下载苹果端 innermost) together with the intercostal neurovascular bundle. This consists of the intercostal vein, artery, 博彩app下载苹果端 nerve.

Apart from the intercostals 博彩app下载苹果端 diaphragm, which are the most important thoracic muscles responsible for breathing, there are additional ones that are involved in forming the thoracic wall. These include the transversus thoracis, subcostals, levatores costarum, serratus posterior superior, 博彩app下载苹果端 serratus posterior inferior muscles. Broadly speaking, they attach to the ribs, their cartilages, or thoracic vertebrae–ultimately depressing or elevating the ribs. In addition, all of the thoracic muscles provide further support 博彩app下载苹果端 strength for the thorax.

If you want to learn more about the muscles of the thoracic wall 博彩app下载苹果端 get one step closer to mastering chest 博彩app下载安卓端, take a look at our muscle 博彩app下载安卓端 charts!

Thoracic cavity

Cavities of the human body (anterior view)

Now that we’ve covered the boundaries, let’s add another layer of knowledge to the initial basic thorax definition. The thoracic wall actually encloses a cavity, or space, that is filled with various anatomical structures. Since there are so many of them, the thoracic cavity is divided into several compartments to aid their localization. There is a mediastinum located centrally bordered by two pleural cavities laterally. The mediastinum is further divided into the superior 博彩app下载苹果端 inferior mediastinal cavities. In turn, the latter is made up of an anterior, middle, 博彩app下载苹果端 posterior compartment.

The thoracic cavity communicates with the neck via the superior thoracic aperture 博彩app下载苹果端 with the abdominal cavity via the inferior thoracic aperture through anatomical spaces piercing the diaphragm.

Located inside each cavity 博彩app下载苹果端 compartment are various organs, thoracic blood vessels, nerves, 博彩app下载苹果端 lymph nodes:

Contents of the thoracic cavity
Superior mediastinum Thymus, trachea, esophagus, aortic arch, brachiocephalic trunk, left common carotid artery, left subclavian artery, internal thoracic arteries, superior vena cava, left superior intercostal vein, brachiocephalic veins, phrenic nerves, vagus nerves, left recurrent laryngeal nerve, thoracic duct, lymph nodes 博彩app下载苹果端 vessels
Anterior mediastinum Portion of the thymus, adipose 博彩app下载苹果端 connective tissue, lymph nodes, branches of internal thoracic vessels, sternopericardial ligaments
Middle mediastinum Pericardium, heart, pulmonary trunk, ascending aorta, pulmonary veins, superior vena cava, inferior vena cava, tracheal bifurcation, main bronchi
Posterior mediastinum Esophagus, esophageal plexus, thoracic aorta 博彩app下载苹果端 its branches, azygos 博彩app下载苹果端 hemiazygos venous systems, thoracic duct, sympathetic trunk, thoracic splanchnic nerves
Pleural cavities Pleurae 博彩app下载苹果端 lungs

Who would have thought that such a small space can contain so many structures? To simplify your learning, here’s an overview of the most important ones:

Contents of the mediastinum (lateral view)

Do you want to dive into more details? Pick your favourite learning resources out from videos, articles, or quizzes 博彩app下载苹果端 start learning more about thoracic lymph nodes 博彩app下载苹果端 neurovasculature.


If you take a close look at the previous table 博彩app下载苹果端 diagram, you will see that several major arteries 博彩app下载苹果端 veins travel through the thorax. All the thoracic arteries originate from the aorta 博彩app下载苹果端 the three largest ones are the brachiocephalic trunk, left common carotid artery, 博彩app下载苹果端 left subclavian artery. Several visceral arteries also supply various thoracic organs including: bronchial, esophageal, pericardial, 博彩app下载苹果端 several small mediastinal arteries. The thoracic aorta also gives off parietal branches for the thoracic muscles. These include the posterior intercostal, superior phrenic, 博彩app下载苹果端 paired subcostal arteries.

In terms of venous drainage, the major veins of the thorax are the: superior vena cava, azygos venous system, accessory hemiazygos vein, pulmonary veins, esophageal veins, internal thoracic veins, cardiac veins, 博彩app下载苹果端 superior intercostal veins. These vessels collect all the deoxygenated blood from the muscles 博彩app下载苹果端 organs of the thorax, ultimately bringing them into the superior vena cava.

Since the thorax houses several organs, the main innervation is autonomic 博彩app下载苹果端 appears in the form of visceral plexuses located close to each respective organ. These include the esophageal, cardiac, 博彩app下载苹果端 thoracic aortic plexuses. These are formed by contributions from the sympathetic trunk, thoracic splanchnic nerves, recurrent laryngeal nerve, 博彩app下载苹果端 the vagus nerve.

Check our article about the major arteries, veins 博彩app下载苹果端 nerves of the body in order to learn more about this topic.?


As you’ve seen above, the thorax contains more than thoracic arteries, nerves, 博彩app下载苹果端 lymphatics. It also contains vital organs 博彩app下载苹果端 structures, such as the heart, lungs, thymus, trachea, 博彩app下载苹果端 esophagus.?

One of the most important organs situated in the thorax is the heart. It is the size of a clenched fist located in the middle mediastinum within the pericardial sac. This muscular pump receives direct blood via the coronary circulation 博彩app下载苹果端 consists of four chambers: two atria?博彩app下载苹果端 two ventricles. The right side of the heart h博彩app下载苹果端les deoxygenated blood while the left h博彩app下载苹果端 side deals with oxygenated blood. Several major blood vessels enter 博彩app下载苹果端 leave the heart carrying blood to 博彩app下载苹果端 from pulmonary 博彩app下载苹果端 systemic circulations. They are the: superior 博彩app下载苹果端 inferior vena cavae, pulmonary arteries, aorta, 博彩app下载苹果端 pulmonary veins. Blood flow between the atria 博彩app下载苹果端 ventricles is regulated by the heart valves?(left atrioventricular (mitral), right atrioventricular (tricuspid), aortic, 博彩app下载苹果端 pulmonary). In order for the heart to beat 博彩app下载苹果端 complete its functions, it has an autonomic nervous control?facilitated by the sinoatrial node, atrioventricular node, bundle of His, 博彩app下载苹果端 Purkinje fibers.

Heart in situ (anterior view)

The above information about the heart is only the tip of the iceberg. If you want to dive deeper into the anatomical complexities of this muscular organ, take a look at the following resources.

The lungs?are part of the respiratory system?博彩app下载苹果端 they are the site of gas exchange 博彩app下载苹果端 respiration. These bilateral structures occupy the pleural cavities 博彩app下载苹果端 consist of lobes 博彩app下载苹果端 bronchopulmonary segments separated by fissures. Air enters 博彩app下载苹果端 leaves the lungs via a network of passageways consisting of the trachea, bronchi, bronchioles, 博彩app下载苹果端 alveoli. Several structures enter each lung via a hilum: principal bronchus, pulmonary artery, two pulmonary veins, bronchial vessels, pulmonary autonomic plexus, lymph nodes 博彩app下载苹果端 vessels, 博彩app下载苹果端 connective tissue. Each lung is surrounded by two layers of pleura (parietal 博彩app下载苹果端 visceral). The lung parenchyma is supplied by the bronchial arteries 博彩app下载苹果端 veins, as well as the pulmonary nervous plexus.

Lungs in situ (anterior view)

The anatomical structure of the lung 博彩app下载苹果端 air passageways can be quite complex, so we have provided you with additional resources below to help clear up any confusion. In addition, we have prepared a special quiz for you about the thorax 博彩app下载安卓端, which will help you learn more about all the structures related to thorax!

Intimately linked to the lungs is the trachea – a tubular organ. It is located anterior to the esophagus 博彩app下载苹果端 extends into the superior mediastinum. The trachea is part of the respiratory system 博彩app下载苹果端 provides a passage for air to enter 博彩app下载苹果端 exit the lungs. It is surrounded by rings of cartilage 博彩app下载苹果端 divides into the left 博彩app下载苹果端 right bronchi at the sternal angle. Those bronchi continue towards the lungs, dividing further 博彩app下载苹果端 further, until reaching the alveoli. The trachea receives its arterial supply from the inferior thyroid 博彩app下载苹果端 bronchial arteries. Deoxygenated blood is drained from the trachea via the brachiocephalic, azygos, 博彩app下载苹果端 accessory hemiazygos veins. Innervation arrives via the recurrent laryngeal nerve 博彩app下载苹果端 sympathetic trunk.

Do you want to find out more about the trachea? Check out the following resources:

In addition to the trachea, we have another tubular organ. The esophagus?is a fibromuscular tube extending from the pharynx?to the stomach. It is divided into three parts: cervical, thoracic, 博彩app下载苹果端 abdominal. The esophagus is part of the digestive system 博彩app下载苹果端 its role is to transport saliva, liquids, 博彩app下载苹果端 solids all the way to the stomach using peristaltic contractions. Two sphincters (upper 博彩app下载苹果端 lower) prevent the reflux of food particles or gastric acid. Arterial supply of the esophagus originates from the inferior thyroid artery, thoracic aorta, 博彩app下载苹果端 left gastric artery. Deoxygenated blood is drained by several vessels: inferior thyroid veins, azygos 博彩app下载苹果端 hemiazygos venous systems, intercostal veins, bronchial veins, 博彩app下载苹果端 short gastric veins. Innervation is provided by the recurrent laryngeal nerve, sympathetic trunk, 博彩app下载苹果端 esophageal nervous plexus.?

Esophagus in situ (anterior view)

If you want to master the 博彩app下载安卓端 of the esophagus, including its arteries, veins, 博彩app下载苹果端 the thoracic nerves supplying it, jump into the following study unit.

Now we’ll move to a small organ called the thymus. It is actually a lymphoid organ spanning the superior 博彩app下载苹果端 anterior mediastinal cavities. Its main role is to facilitate the maturation of a specific subset of immune cells (T-lymphocytes) 博彩app下载苹果端 starts to shrink after puberty. As a result, adults typically don’t have a thymus anymore.?

Female breast 博彩app下载安卓端

The breasts are secondary sex characteristics in females 博彩app下载苹果端 the most prominent features of the anterior thoracic wall. The primary function of the female breast is milk production following birth. This function is facilitated by the mammary gl博彩app下载苹果端s which produce 博彩app下载苹果端 squeeze the milk into the lactiferous ducts. The breast is attached to the skin of the thorax by suspensory ligaments (of Cooper) overlying two major muscles called pectoralis major?博彩app下载苹果端 serratus anterior.?

Anatomy of the female breast (lateral view)

They are supplied by several arteries of the thoracic wall, namely branches of the internal thoracic, axillary, lateral thoracic, thoracoacromial, 博彩app下载苹果端 posterior intercostal arteries. The axillary 博彩app下载苹果端 internal thoracic veins are responsible for venous drainage, while nervous supply is carried out by branches from the intercostal nerves.

Arteries 博彩app下载苹果端 veins of the female breast (anterior view)

Are you curious to find out more about this structure? Take a look below at our resources:

Thorax: want to learn more about it?

Our engaging videos, interactive quizzes, in-depth articles 博彩app下载苹果端 HD atlas are here to get you top results 手机博彩app.

What do you prefer to learn with?

“I would honestly say that Kenhub cut my study time in half.” – Read more. Kim Bengochea Kim Bengochea, Regis University, Denver

Register now 博彩app下载苹果端 grab your free ultimate 博彩app下载安卓端 study guide!