Thorax Anatomy: Thoracic Cage, Lungs, Mediastinum, Heart & Major Structures

Thorax Anatomy: Thoracic Cage, Lungs, Mediastinum, Heart & Major Structures

pediagenosis    October 02, 2026    Comment   

LUNGS IN SITU: ANTERIOR VIEW

        Thorax

Before describing the anatomy of the heart, it is helpful to review other anatomic features of the thoracic cavity and organs. The thorax proper constitutes the upper part of the body or trunk, with a shape between a barrel and a truncated cone that is functionally favorable. Although the intrathoracic pressure is often subatmospheric, the chest wall is still able to retain its integrity by means of rather thin, lightweight skeletal elements. The thoracic cavity occupies only the upper part of the thoracic cage. The abdominal (peritoneal) cavity reaches upward as high as the lower tip of the sternum, affording protection to large, easily injured abdominal organs such as the liver, spleen, stomach, and kidneys.

Esophagus in Situ Anatomy

Esophagus in Situ Anatomy

pediagenosis    September 27, 2026    Comment   

Esophagus in Situ Anatomy

Common carotid artery, Anterior scalene muscle, Phrenic nerve, Posterior scalene muscle, Brachial plexus, Subclavian artery, Thyrocervical trunk, Vagus nerve (CN X) 1st rib (cut), Brachiocephalic trunk, Trachea, Arch of aorta, Arch of azygos vein, Right main bronchus, Thoracic part of esophagus, Esophageal plexus, Mediastinal part of parietal pleura (cut edge), Anterior vagal trunk (CN X), Inferior vena cava (cut), Hepatic veins (cut), 

Autonomic Nerves of Thorax Anatomy

Autonomic Nerves of Thorax Anatomy

pediagenosis    September 26, 2026   

Autonomic Nerves of Thorax Anatomy

Cervicothoracic (stellate) ganglion, Ansa subclavian, Cervical cardiac nerves (sympathetic and vagal), Thoracic (sympathetic) cardiac branches, Sympathetic trunk, Vagus nerve (CN X) (cut) and branches to cardiac and pulmonary plexuses, Thoracic (sympathetic) cardiac branches, Anterior pulmonary plexus, Gray and white rami communicantes, Posterior pulmonary plexus (protruding from behind right bronchus), 6th intercostal nerve, 6th thoracic ganglion, Greater thoracic splanchnic nerve, Sympathetic branch to esophageal plexus, Thoracic duct, 

Topography and Constrictions of Esophagus Anatomy

Topography and Constrictions of Esophagus Anatomy

pediagenosis    September 07, 2026   

Topography and Constrictions of Esophagus Anatomy

Incisor tooth, Oropharynx, Epiglottis, Piriform recess, Thyroid cartilage, Cricoid cartilage, Thyroid cartilage, Cricoid cartilage, Cricopharyngeus (muscle) part of inferior pharyngeal constrictor muscle, Pharyngoesophageal constriction, Average length in centimeters, Thoracic (aortobronchial) constriction, Trachea, Arch of aorta, Left main bronchus,

Esophagogastric Junction Anatomy

Esophagogastric Junction Anatomy

pediagenosis    April 28, 2025    Comment   

Esophagogastric Junction Anatomy

Longitudinal esophageal muscle, Circular esophageal muscle, Gradual slight muscular thickening, Phrenicoesophageal ligament (ascending or upper limb), Supradiaphragmatic fascia, Respiratory diaphragm, Infradiaphragmatic (transversalis) fascia, Phrenicoesophageal ligament (descending limb), Peritoneum, Cardiac notch, Esophageal mucosa, Submucosa, Respiratory diaphragm,

ATRIA AND VENTRICLES

ATRIA AND VENTRICLES

pediagenosis    November 07, 2024    Comment   

ATRIA AND VENTRICLES

RIGHT ATRIUM AND RIGHT VENTRICLE 

Right Atrium

The right atrium consists of two parts: (1) a posterior smooth-walled part derived from the embryonic sinus venosus, into which enter the superior and inferior venae cavae, and (2) a thin walled trabeculated part that constitutes the original embryonic right atrium. The two parts of the atrium are separated by a ridge of muscle. This ridge, the crista terminalis (see Plate 1-7), is most prominent superiorly, next to the SVC orifice, then fades out to the right of the IVC ostium. Its position corresponds to that of the sulcus terminalis externally (see Plate 1-6). Often described as a remnant of the embryonic right venous valve. the crista terminalis actually lies just to the right of the valve.

EXPOSURE OF THE HEART

EXPOSURE OF THE HEART

pediagenosis    November 05, 2024    Comment   

EXPOSURE OF THE HEART

Sternocostal Aspect

ANTERIOR EXPOSURE

Within the pericardium lies the heart, a hollow, muscular, four-chambered organ suspended at its base by the great vessels. In situ the heart occupies an asymmetric position, with its apex pointing anteriorly, inferiorly, and about 60 degrees toward the left. Its four chambers are arranged in two functionally similar pairs, separated from each other by the cardiac septum (see Plate 1-5). Each pair consists of a thin-walled atrium and a thicker-walled ventricle.

Pericardium Anatomy

Pericardium Anatomy

pediagenosis    May 09, 2021    Comment   

Pericardium Anatomy

Fibrous pericardium

The fibrous pericardium is a sac of dense connective tissue surrounding the heart. In addition to the heart, it encloses the roots of the great arteries and veins and is covered on its inner surface by serous pericardium (see below). The broad base of the fibrous pericardium is attached to the central tendon of the diaphragm (Fig. 2.29) and is pierced by the inferior vena cava.

Fig. 2.29 The fibrous pericardium and phrenic nerves revealed after removal of the lungs.

Superiorly, the sac fuses with the adventitial layers of the aorta, pulmonary trunk and superior vena cava. On each side, the posterior part of the sac blends with the walls of the pulmonary veins.

Heart Anatomy

Heart Anatomy

pediagenosis    May 09, 2021    Comment   

Heart Anatomy

External features

The heart, enclosed in pericardium, occupies the middle mediastinum. It is roughly cone-shaped and lies behind the sternum with its base facing posteriorly and its apex projecting inferiorly, anteriorly and to the left, producing the cardiac impression in the left lung.

Fig. 2.31 Transverse CT image at the level of the eighth thoracic vertebra.

The heart consists of four chambers, namely the right and left atria and the right and left ventricles (Fig. 2.31). A fat-filled groove, the coronary or atrioventricular sulcus, separates the surfaces of the atria from the ventricles and carries the right and left coronary arteries and the coronary sinus. The right atrium receives the superior and inferior venae cavae and the coronary sinus. The right and left pulmonary veins drain into the left atrium. The right ventricle is continuous with the pulmonary trunk while the left ventricle opens into the ascending aorta.

Lymphatic Drainage of Breast Anatomy

Lymphatic Drainage of Breast Anatomy

pediagenosis    October 18, 2020   

Lymphatic Drainage of Breast Anatomy

Lateral axillary (humeral) nodes, Posterior axillary (subscapular) nodes, Central axillary nodes, Parasternal nodes,

Thorax Surface Anatomy

Thorax Surface Anatomy

pediagenosis    October 18, 2020   

Thorax: Surface Anatomy

Sternocleidomastoid muscle, Jugular notch, Deltoid muscle, Body of sternum, Nipple, Cephalic vein, External abdominal oblique muscle, Rectus abdominis muscle,

Mammary Gland Anatomy

Mammary Gland Anatomy

pediagenosis    October 18, 2020   

Mammary Gland Anatomy

Anterolateral dissection, Pectoralis major muscle (deep to pectoral fascia), External abdominal oblique muscle, Pectoral fasciae, Intercostal muscles, Serratus anterior muscle, Clavicle, Subclavius muscle 2nd rib, Pectoralis major muscle, Intercostal vessels and nerve, Lung 6th rib.

Arteries of Mammary Gland Anatomy

Arteries of Mammary Gland Anatomy

pediagenosis    October 18, 2020   

Arteries of Mammary Gland Anatomy

Subclavian artery, Internal thoracic artery and its perforating branches, Medial mammary branches, Axillary artery, Brachial plexus, Brachial artery, Lateral thoracic artery and, Lateral mammary branches, Lateral mammary branches of lateral cutaneous branches of posterior intercostal arteries, Axillary tail (of Spence), Long thoracic nerve.

Lymph Vessels and Nodes of Mammary Gland Anatomy

Lymph Vessels and Nodes of Mammary Gland Anatomy

pediagenosis    October 18, 2020   

Lymph Vessels and Nodes of Mammary Gland Anatomy

Parasternal nodes, Apical axillary, Interpectoral (Rotter’s) nodes (subclavian) nodes, Central axillary nodes, Lateral axillary (humeral) nodes, Posterior axillary (subscapular) nodes, Anterior axillary (pectoral) nodes, Pathway to anterior mediastinal nodes.

Mediastinal Structures Anatomy

Mediastinal Structures Anatomy

pediagenosis    October 13, 2020    Comment   

Mediastinal Structures Anatomy

Brachiocephalic veins

On each side, the brachiocephalic vein is formed in the root of the neck by the union of the internal jugular and subclavian veins. At its origin, the vein lies behind the sternoclavicular joint and in front of the first part of the subclavian artery.

Mediastinum Anatomy

Mediastinum Anatomy

pediagenosis    June 03, 2019    Comment   

Mediastinum Anatomy

The central part of the thorax between the two pleural cavities contains a group of structures collectively termed the mediastinum. These include the heart and great vessels, the trachea and the oesophagus. The mediastinum extends from the superior thoracic aperture above to the diaphragm below and from the sternum in front to the thoracic vertebral bodies behind (Fig. 2.28). By convention, the mediastinum is divided into superior and inferior parts by an imaginary horizontal plane passing through the manubriosternal joint and the lower part of the fourth thoracic vertebra. The superior mediastinum lies between this plane and the superior thoracic aperture and contains the superior vena cava and its tributaries, the arch of the aorta and its branches and the trachea. Also passing through this region are the oesophagus, the thoracic duct and the right and left vagus and phrenic nerves.

Bronchi Anatomy

Bronchi Anatomy

pediagenosis    June 03, 2019    Comment   

Bronchi Anatomy

The bifurcation of the trachea in the mediastinum gives rise to the right and left main (principal) bronchi (Fig. 2.26).

Lungs Anatomy

Lungs Anatomy

pediagenosis    June 03, 2019    Comment   

Lungs Anatomy

The two lungs lie in the thoracic cavity and are separated by the structures in the mediastinum (Fig. 2.19). Although the lungs of infants are pink, those of older individuals may have a mottled appearance due to deposits of inhaled carbon. Living lungs are elastic, enabling their volumes to change during ventilation, in contrast to embalmed lungs, which are rigid and often bear the imprints of adjacent structures. Each lung is covered in visceral pleura and is cone-shaped, with the base or diaphragmatic surface directed downwards and the apex upwards. The costal surface is smoothly convex, while the mediastinal surface is irregular and bears the hilum of the organ. Fissures are usually present, and divide each lung into lobes (usually three lobes on the right and two on the left). Most of the lung consists of the peripheral part of the respiratory tract and the associated pulmonary vascular system. Having entered the lung, the bronchi and pulmonary vessels subdivide extensively (Fig. 2.26).

Pleura Anatomy

Pleura Anatomy

pediagenosis    June 03, 2019    Comment   

Pleura Anatomy

The thoracic cavity lies within the walls of the thorax and is separated from the abdominal cavity by the diaphragm. The cavity contains the right and left lungs, each surrounded by a serous membrane called the pleura. Between the lungs is a central partition, the mediastinum, which includes the heart and great vessels, the trachea and the oesophagus. Superiorly, numerous mediastinal structures enter or leave the root of the neck through the superior thoracic aperture (p. 322). Inferiorly, important structures including the aorta, inferior vena cava and oesophagus pass between the mediastinum and the abdomen through openings in the diaphragm (p. 203).

Thoracic Wall Anatomy

Thoracic Wall Anatomy

pediagenosis    June 03, 2019   

Thoracic Wall Anatomy

Skin

The skin covering the thorax receives its nerve supply from lower cervical and upper thoracic spinal nerves. Above the level of the manubriosternal joint, C4 gives cutaneous innervation, while tho- racic nerves T2–T11 provide the dermatomes for the remainder of the thoracic wall. The first thoracic nerve does not contribute to the cutaneous nerve supply of the thorax but innervates some of the skin of the upper limb (Figs 1.35 & 3.6).