Central Tendon of Diaphragm The structure indicated is the central tendon of the diaphragm. The diaphragm is a musculotendinous structure which seals the inferior thoracic aperture and separates the abdominal cavity from the thoracic cavity. When it contracts, it flattens, increasing the intrathoracic volume and thereby allowing air to enter the lungs. The central tendon is an aponeurosis which forms the top of the dome-shaped diaphragm. It blends with the fibrous pericardium above, helping to maintain it in place. The inferior vena cava passes through the central tendon at the level of the 8th vertebra.
Middle Lobe of Right Lung The right lung consists of three lobes: superior lobe inferior lobe middle lobe. These lobes are separated by two fissures, known as the oblique fissure and the horizontal fissure. The oblique fissure separates the middle and inferior lobes, whereas the horizontal fissure separates the superior and middle lobes. Pictured here is the middle lobe of the right lung. The left lung, on the other hand only has two lobes separated by one fissure. The superior lobe is separated from the inferior lobe by the oblique fissure. Learn more about the respiratory system in this tutorial.