The mediastinum is a midline region of the thoracic cavity; located between the two pleural cavities of the lungs. It extends from the superior thoracic aperture to the diaphragm and is bordered anteriorly by the sternum and posteriorly by the thoracic vertebrae. The mediastinum can be subdivided into compartments for descriptve purposes.

The pulmonary trunk is the origin of the right and left pulmonary arteries and lies entireley within the pericardial sac. It arises from the right ventricle and ascends in front of the ascending aorta, then courses posteriorly and to the lefty. It then bifurcates at the sternal angle (T4) into the right and left pulmonary arteries. The pulmonary trubnk is attatched to the aortic arch by a fibrous cord called the ligamentum arteriosum. The remnant of an important fetal blood vessel (ductus arteriosus) that links the pulmonary and systemic circuits during fetal development. Within the lungs the pulmonary arteries are anterior to the bronchi; which are anterior to the pulmonary veins.

The common bile duct continues a caudal descent along with the hepatic artery and portal vein, within the hepatoduodenal ligament. It then curves slightly to the rightr away from the portal vein, and then courses posterior and medial to the first part of the duodenum. Behind the head of the pancreas; the common bile duct follows a groove on the posterior surface of the pancreatic head. It then peirces the medial wall of the second part of the duodenum, along with the main pancreatic duct ( duct of Wirsung), through the ampulla of vater. The ends of both ducts are surrounded by the circular muscle fibers of the sphincter of Oddi.

The larynx is the bony skeleton that surrounds and  protects  the vocal cords and is commonly called the voice box. It begins at the laryngopharynx and continues to the  trachea. The larynx consists of  an outer skeleton made up of nine cartilages that extend from apprximatley C3-C6. These cartilages are connected to each other by ligaments and are moved by numerous muscles. Three of the cartilages are unpaired and include: the thyroid, the epiglottis and the cricoid. The three paired cartilages are  the arytenoid, the corniculate, and the cuneform.

Theopercular segment of the  middle cerebral artery (M3) emerges from the sylvan fissure at the sylvan point, to split into the superior and inferior groups of the cortical branches. The cortical branches supply the entire convex surface of the cerebral hemispheres.