Muscles Used in Ventilation (Breathing). These muscles alter the size of the thoracic cavity during breathing. The diaphragm is the most important. It is domed shaped and consists of two parts: a peripheral muscular portion and a tendinous central portion called the central tendon upon which the muscle fibers insert. Two other muscles, external intercostals and internal intercostals, occupy the spaces between the ribs.
R Lymphatic Duct - drains R upper limb, R side of the head & thorax. The larger Thoracic Duct, runs superiorly, receives from the L side of the Thorax, L Upper Limb & L side of the Head. Arises anterior to the 1st 2 lumbar vertebrae as an enlarged sac, the Cisterna Chyli, collects lymph from 2 Lumbar Trunks that drain Lower Limbs & Intestinal Trunk that drains Digestive Organs. Ducts empty Nto venous circulation @ the jnction of the internal jugular & subclavian vein on its own s
greys thoracic cavity - Google Search
Thoracic cavity of a man, showing internal organs: a b c upper lobes, middle and lower right lung, d, e, upper and lower lobes f heart, g artery, h vein; i, aorta; k, superior vena cava, Trousset Enc.