Key Points

• The diaphragm is the most important respiratory muscle.
• The diaphragm has two major components: a central noncontractile tendon and a periphery consisting of three groups of muscle fibers.
• Diaphragmatic innervation and blood supply are crucial to decide the incision for any transdiaphragmatic approach.
• The structure of the diaphragmatic muscle fibers is extremely resistant to fatigue and is able to adapt to different situations, from rest to extreme efforts.
• Hyperinflation in patients with emphysema causes a loss of the zone of apposition and compromises the anteroposterior and transverse expansion of the rib cage.

The diaphragm is a musculotendinous septum that separates the thoracic from the abdominal cavity. It is the most important muscle of inspiration and is responsible for most of the work of breathing both in normal individuals and in patients with lung disease. The physiology and pathophysiology of the diaphragm can be easily inferred from the anatomic arrangement of this structure and its embryologic development [1],[2],[3],[4],[5].