Mediastinum: Sternal angle angle Lower border of T4 It is the partition between the two pleural cavities and lungs. It includes a large number of structures It is subdivided into: -Superior mediastinum -Inferior mediustinum : anterior, middle and posterior Superior mediastinum: Esophagus Trachea Arch of Aorta Big branches of Aortic arch Brachiocephalic ( innominate) veins Upper half of superior vena cava Phrenic nerves Vagi nerves Middle mediastinum: Pericardium Heart Pulmonary trunk Ascending Aorta Lower half of SVC Upper part of IVC Bifurcation of trachea Posterior mediastinum: Descending thoracic Aorta Azygos and hemiazygos veins vagi ِ Sternal angle angle Lower border of T4

Fibrous and parietal layer of serous: phrenic Pericardium: 1-It is a fibroserous sac which surrounds the heart and adjacent parts of the big vessels originating from or ending into the heart. 2-It is formed of outer fibrous sheath-----fibrous pericardium inner serous sac----------serous pericardium Fibrous pericardium: - Shape: conical - Apex, base Relations: ant, post, on each side Serous pericardium: -It is closed serous sac covered by fibrous pericardium and it is invaginated by the heart from behind and above -Layers 3- Arterial supply and Venous drainage: Fibrous and parietal layer of serous: internal thoracic and descending Aorta Visceral layer of serous-----coronary arteries and drained into coronary sinus 5- Nerve supply: Fibrous and parietal layer of serous: phrenic Visceral layer of serous-----autonomic 6- Applied Anatomy: pericardial puncture

Heart: -It is a pyramidal, hollow, four-chambered, muscular organ (forming the major part of middle mediastinum) -It is formed of 4 chambers -Atrioventricular groove (coronary sulcus) -Anterior and inferior intervetricular grooves -Interatrial and intervetricular septums - Being pyramidal it has: apex: direction, formation, site, relation base: direction, formation, site, relation 4 surfaces: sternocostal, diaphragmatic, right and left surfaces each: direction, formation, site Post. I.V. groove Ant. I.V. groove

Right Atrium: Cavity of RA: -Site Post-----sinus venarum (smooth) -Receives venous blood from whole body SVC---upper post. IVC----lower post. Sulcus terminalis -Right auricle Cavity of RA: Post-----sinus venarum (smooth) Ant------atrium proper (rough) crista terminalis (musculi pectinati) Interatrial septum shows-----fossa ovalis Opening in RT: SVC, IVC, coronary sinus, tricuspid opening

Right Ventricle: -Site Cavity of RV: Inflow part----- (rough)----trabeculae carnae (muscular projections) ----Papillary muscles----Chordae tendinae supporting the tricuspid valve Outflow part-----(smooth)-----infundibulum (why?) Interventricular septum Opening in RV: Tricuspid opening and valve Pulmonary opening and valve

Left Atrium: Cavity of RA: Post----- (smooth) receives pulmonary veins -Site -Receives 4 pulmonary veins -Left auricle Cavity of RA: Post----- (smooth) receives pulmonary veins Ant------ (rough) left auricle Opening in RT: 4 pulmonary veins Mitral opening

Left Ventricle: Pulmonary valve -Site Cavity of LV: Aortic valve Inflow part----- (rough)----trabeculae carnae (muscular projections) Outflow part-----(smooth)-----vestibule (why?) Interventricular septum Thickness Opening in LV: Mitral opening and valve Aortic opening and valve Pulmonary valve Aortic valve Tricuspid valve Mitral valve Papillary muscle

Conducting system of the heart: Formed of modified myocardial fibers called (Purkinje fibers) which are specialized for initiation, conduction and maintenance of the cardiac rhythm. 1- Sinoatrial (SA) node-----site, function 2- Atrioventricular (AV) node-----site 3- Atrioventricular (AV) bundle-----right , left branches

Post. Ant. Nerve supply of the heart: Arterial supply of the heart: 1- Sympathetic innervation: Stimulates heart rate (tachycardia) coronary vasodilatation 2- Paraympathetic innervation: Slows heart rate (bradycardia) Coronary vasoconstriction 3- Pain fibers: upper thoracic segments of the spinal cord Arterial supply of the heart: 1- right coronary artery: Origin, Course, branches 2- Left coronary artery: Origin, Course, divisions, branches Venous drainage of the heart: 1- Coronary sinus: Legnth, site, receives all venous drainage of the heart as: great, middle and small cardiac veins Coronary sinus Lt coronary A. Circumflex A. Rt coronary A. Ant. IV A. +great cardiac V. Post. IV A. +middle cardiac V. Ant. Post.