Sympathetic fibres from T2 - T4 and parasympathetic fibres from the vagus, form a posterior pulmonary plexus at the root of the lung.

Fibres then pass around the root of the lung to form the anterior pulmonary nerve plexus. Fibres then accompany the blood vessels and bronchi into the lungs.

The lower margin of the pleura is at the level of:

• The eighth rib in the midclavicular line
• The tenth rib in the midaxillary line (lowest level)
• The twelfth thoracic vertebra at its termination.

Each lung has an oblique fissure but only the right lung has a transverse fissure.

The trachea extends from the lower margin of the cricoid cartilage, at the level of the sixth cervical vertebra, to the carina.