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.