Thorax

The superior thoracic aperture contains structures emerging from the thorax and entering the head and neck and upper limb. In this specimen, both clavicles, key venous structures and other musculature have been removed. Despite this, other important components of anatomy can be observed. Key structures include the Trachea seen most superiorly with a thick ring of cartilage, rib one has been exposed prior to meeting its costal cartilage, travelling in a lateral to medial direction and the anterior scalene muscle inserting into Rib one superiorly.In regards to the blood supply, The right subclavian can be seen superior to rib one, giving off the thyrocervical trunk to supply the neck, the left subclavian can also be seen superior to rib one, giving off the suprascapular artery and both the left and right common carotid can be seen superiorly with the left also containing a clear left vagus nerve.Travelling inferiorly from the cranium, the vagus nerve follows the common carotid arteries in the carotid sheath which can be seen in the left common carotid artery. The left phrenic nerve remains unclear until it emerges in the mediastinum. Components of the left brachial plexus can be seen, from roots to trunks. Numerous smaller branches move off, including the Dorsal Scapular nerve.In the mediastinum, key structures can be identified in the mediastinum of the thorax. However, other pieces of anatomy including the inferior vena cava, right vagus nerve and some coronary vessels cannot be observed in this specimen. The Right phrenic nerve can be traced posteriorly to the heart, this has been shifted from its normal anterior to the heart position during dissection. Also seen is the Left phrenic nerve is still contained in its connective tissue and remains located anteriorly to the heart, until reaching the diaphragm for innervation. The left vagus nerve can be seen posterior to the heart and is easier to identify superiorly following the left common carotid artery in the carotid sheath. Note the left recurrent laryngeal nerve moving under the aorta.The Arch of aorta giving branches of brachiocephalic and left common carotid superior to the heart. The left subclavian artery can be seen just posterior to the left common carotid. With the pulmonary trunk exiting immediately superior to the heart. The Left anterior descending carotid artery can be observed cascading anteriorly on the heart with the superior vena cava can been seen to the right of the aorta and posterior.The inferior thorax shows Ribs 8 through 12 on the specimen, the musculature in-between these ribs can also be seen. Notably, the direction of external intercostal muscle inferomedially can be seen as it progresses into a layer of fascia.As observed in the specimen, the right hemidiaphragm is located more superiorly than the left hemidiaphragm, and this is due to the presence of the liver on the right side of the abdominal cavity.

The hilum of a lung is the point at which visceral and parietal pleura meet and functions with the pulmonary ligament as the lungs only connection with the rest of the body. This connection includes the Pulmonary Artery, Superior and Inferior Pulmonary Veins, Main Bronchi, Nerves and Lymphatics.As the definition of an artery involves carrying blood AWAY from the heart, this will be deoxygenated blood in the pulmonary system, in contrast with the systemic circulation. Similarly, veins carry blood TOWARDS the heart, meaning it will be oxygenated in the pulmonary system.With the specimen cut in a sagittal plane in line with the cardiac impression, nerves and lymphatics are difficult to identify however the groove from the oesophagus as it descends posteriorly to pierce the diaphragm can be seen alongside the cardiac impression (of the right atrium) is notable anterior to the hilum of the right lung; the right main bronchi and its subsequent divisions into lobar bronchi, found in this specimen more posterior in the hilum; he pulmonary artery and its divisions, located most superior within the hilum; the superior and inferior pulmonary veins and their divisions which are most inferior and anterior in the specimen. the oblique and horizontal fissures along the lateral surface of the specimen and the Hilar lymph nodes around the hilum on the medial surface of the lung.The diaphragmatic surface is found inferiorly and the costal visceral surface is on the posterior of the specimen.

This model is a cross-section of the thorax at the level of the T6 vertebra. Beginning posteromedially at the spinal cord within the vertebral canal, then moving radially, the costovertebral joints of the 6th ribs are visible, followed by several other ribs around the margin of the thoracic cavity, a pair of which unite anteriorly with the sternum via the costosternal joints. Additionally, the oesophagus and descending aorta are visible anterior and lateral to the T6 vertebral body, respectively.Inside the plural space, lined by the parietal pleura, reside the inferior and middle lobes of the right lung and the inferior lobe of the left lung.In the middle mediastinum the heart, within the pericardium, is transacted to reveal the left atrium posteriorly, then moving clockwise, the aortic valve, right ventricle and the right atrium.

In this specimen the heart itself has been removed to demonstrate the reflections of parietal peritoneum and the orientation of the heart relative to other structures, including the diaphragm (diaphragmatic surface) and the lungs (left and right pulmonary surfaces). The pericardium is the multilayered fibroserous sac that encloses the heart and is continuous with the serous visceral pericardium (epicardium) of the heart itself. In normal anatomical position, the boundaries of the parietal pericardium are also the boundaries of the middle mediastinum (what we call coterminous). The internal surface of the parietal peritoneum has been false coloured to aid in identifying the regions of the heart that are normally positioned in these parts of the middle mediastinum.The base of the heart is roughly rectangular and projects superiorly and posteriorly (anterior to the hilum of the lungs). It can be seen on the model as the most posterior surface left by the impression of the heart. It is formed by the left atrium (pink) (and to a lesser extent the right atrium [blue-green]) and the proximal parts of the great vessels (red and blue) as they enter and leave the heart. This is also the ‘fixed’ region of the heart, anchoring the heart through the origins of the great vessels where the visceral and parietal serous pericardium are reflected and continuous. The transverse pericardial sinus (clinically relevant for some cardiac surgical procedures) is visible between the pulmonary arteries (red) and the bases of the superior vena cava, pulmonary trunk, and ascending aorta. Inferior to the pulmonary veins, the depressed region formed by the left atrium and left ventricle is termed the oblique pericardial sinus.From the base, the heart projects anteriorly, inferiorly and towards the left side of the thorax. The most inferior and lateral point is the apex. The apex is formed by the inferolateral part of the left ventricle (yellow) and is normally found in the left fifth intercostal space along the midclavicular line.Within the mediastinum, the heart rests on the diaphragmatic surface, consisting mainly of left ventricle (and to a lesser extent the right ventricle [light green]). This is the most inferior aspect of the heart and is separated from the base (the posterior surface) by the coronary sinus. It extends from the base of the heart to its apex. On the model it is the area that is just anterior and inferior to the ostium of the inferior vena cava.The pulmonary surfaces are the broad and convex right and left lateral sides of the heart. The left pulmonary surface reflects onto the left lung and consists mainly of the left ventricle. The right pulmonary surface reflects onto the right lung and consists of the right atrium.The heart also has an anterior surface that consists mostly of the right ventricle with some right atrium on the right and left ventricle on the left. In this model this surface cannot be appreciated as it has been dissected deep to the anterior surface. The portion of the pericardium that can be seen being reflected to either side would have covered, in part the anterior surface before they were reflected.Great VesselsThe aorta carries oxygenated blood from the heart into the systemic circulation. It begins as the ascending aorta and originates from the aortic orifice at the base of the left ventricle of the heart. The left and right coronary arteries branch off immediately superior to the aortic orifice from the left and right aortic sinuses respectively to supply the heart muscle itself. The vessel moves superiorly to the level of the second right costal cartilage, the sternal angle, and is then referred to as the arch of the aorta. It becomes the descending or thoracic aorta when the arch moves inferiorly to the vertebral level T4. It spans down to T12 level and supplies much of the thorax.The superior vena cava is a large vein is formed primarily by the union of the right and left brachiocephalic veins. It drains directly into the right atrium at the SVC ostium, carrying a significant portion of deoxygenated blood of the upper body.The inferior vena cava is another large vein that drains much of the deoxygenated blood of the lower body, with many tributaries contributing to it throughout the trunk. It drains directly into the right atrium at the IVC ostium.Pulmonary VesselsThe pulmonary trunk arises from the right ventricle of the heart. It bifurcates to give rise to the left and right pulmonary arteries left of the midline just inferior to vertebral level T4/5 and the arch of the aorta. These carry deoxygenated blood to the lungs, entering at the root of the lung in the hilum.There are four pulmonary veins in total. A superior and inferior pulmonary vein for each side, left and right. They carry oxygenated blood from the lung, beginning at the hilum and passing through the root of the lung, to the left atrium of the heart.Transverse and Oblique Pericardial SinusThe transverse sinus can be described as the common point of parietal and visceral pericardium. This is located beneath the aorta and pulmonary trunk and depicts a tunnel.In contrast to the tunnel-like transverse sinus, the oblique pericardial sinus is more like an ocean bay. The two types of pericardium here also meet, and it is located between the pulmonary veins.

The lung has been dissected following a parasagittal plane, removing the mediastinal surface. Ordinarily, the pulmonary arteries, veins and bronchi can be observed entering the lung in the hilum – but the primary bronchi cannot be seen in this specimen as they have already divided substantially. It is unclear how far laterally the specimen has been dissected hence the bronchi subdivision level (secondary or tertiary) cannot be determined.The cardiac impression is formed by the left ventricle of the heart resting on the mediastinal surface of the lung. Although the lung has been dissected following a parasagittal plane, the cardiac impression can still be observed as it is the most concave area of the medial surface of the lung.The lung sits above the diaphragm, forming the concave diaphragmatic surface. The pleura has not been preserved in this specimen, but ordinarily, there exists a diaphragmatic recess bounded by the costal and diaphragmatic pleura. This would lie between the lung’s diaphragmatic impression and the diaphragm.

This 3D model represents the complimentary section to the TW 63 right lung hilum 3D model within our series and provide a direct contrast to the TW 61 left lung section. While expressing few discrete features, this 3D model affords a view of the major structural elements of the right lung from the apex to the base. On the lateral aspect, the well-developed oblique and horizontal fissures divide the lung into its three lobes (superior, middle, inferior) – and the cross-section demonstrates the depth of these fissures into the deep portions of the organ itself. The rib impressions have been highlighted running from the apex to the base, and the extremely concave diaphragmatic surface on the section reflects the strong doming of the right hemisphere of the diaphragm in life due to the underlying liver.