The lung hila or roots are found on the medial aspect of each lung. The left and right lung roots are similar but not identical. The roots of the lung lie between T5 to T7 vertebrae ⁵. A hilar point is a point where the upper lobe vein crosses over the pulmonary artery. A hilar angle is the angle between the vessels at the hilar point, which usually measures 120° ⁵.

Gross anatomy

Left hilum

The left hilum lies below the arch of the aorta and anterior to the descending aorta. The left main bronchus lies at the most posterior aspect of the hilum, with the left superior pulmonary vein located anteriorly and the left inferior pulmonary vein occupying the inferior portion of the hilum. The left pulmonary artery is anterosuperior to the left main bronchus. Pulmonary veins always lie anteroinferior to the pulmonary artery ⁵.

Right hilum

The right hilum lies below the arch of the azygous vein, posterior to the superior vena cava and right atrium. Right pulmonary veins are located at the anterior part of the hilum, followed by right pulmonary arteries, and lobar bronchi ⁵.

The structures of the lung hilum are enclosed in a sleeve of pleura continuous below with the pulmonary ligament ⁵.

In addition to the structures described above, each root contains bronchial vessels, autonomic nerves, lymph nodes, and lymphatic channels.