ORIENTATION: VIEWING HEART IN AXIAL CT AND MRI Orientation of heart in axial CT and MRI 20 MINUTE ANATOMY VIDEOS No sinner is ever saved after the first twenty minutes of a sermon - Mark Twain RV RA LV LA 4 CHAMBERED HEART 5 CHAMBERED HEART? INVERTED Y SHAPE?

ORIENTATION: THORACIC CONTENTS ANTERIOR VIEW R L Esophagus Trachea Subclavian V. Left Int. Jugular V. AORTA Pulmonary Trunk Structures at Root of Lung diaphragm R. Brachiocephalic V. Sup. Vena Cava

POSTERIOR VIEW INCLUDING TRACHEA, ESOPHAGUS 3) Pulmonary Veins 1) Arch of Aorta 2) Pulmonary Arteries 2a) Trachea (bifurcation) Esophagus, Thoracic duct IVC diaphragm L R Order similar to root of Lung

HEART IS ON LEFT: ROTATED SO LEFT ATRIUM IS IN MIDLINE Left Atrium - receives Pulmonary Veins from both sides Pulmonary Veins Pulmonary Veins RV LA Right Ventricle - anterior

POSTERIOR VIEW: KNOW SEQUENCE Pulmonary Veins 3) Pulmonary Veins 1) Arch of Aorta 2) Pulmonary Arteries SVC IVC

ANTERIOR VIEW AT TOP (SUPERIORLY) - VEIN IN FRONT OF ARTERIES Arch of Aorta Left Brachiocephalic Vein SVC Right Brachiocephalic Vein Left Common Carotid A Left Subclavian A Brachiocephalic Trunk ANTERIOR VIEW

RV Arch of Aorta Ascending Aorta Pulmonary Trunk - from Conus Arteriosus ANTERIOR VIEW PULMONARY TRUNK - arises from Right Ventricle; crosses anterior to Ascending Aorta; then branches

Conus Arteriosus

PULMONARY TRUNK ON LEFT IN AXIAL SECTIONS RV RA LV LA CONUS ARTERIOSUS EXTENDS TOWARD LEFT; THEN PULMONARY TRUNK BIFURCATES Y Conus Arteriosus

AORTA ARISES IN MIDDLE OF HEART AXIAL SECTIONS LOOK LIKE 5 CHAMBERED HEART RV RA LV LA

POSTERIOR VIEW: KNOW SEQUENCE Pulmonary Veins 3) Pulmonary Veins 1) Arch of Aorta 2) Pulmonary Arteries SVC IVC L R

ORIENTATION: VIEWING HEART IN AXIAL CT AND MRI Orientation of heart in axial CT and MRI RV RA LV LA

RV RA LA LV * - AORTA IN CENTER OF HEART CT, MRI VIEW HEART FROM BELOW R L IMAGE FLIPPED VERTICALLY

Diaphragm Inferior vena cava Esophagus Azygous vein Thoracic (descending) aorta Muscles of ventricles R L START AT DIAPHRAGM

Inferior vena cava Interventricular septum Azygous vein Esophagus Thoracic (descending) aorta Left ventricle Right ventricle 2 CHAMBERED HEART - ventricles only R L

Thoracic (descending) aorta Esophagus Left ventricle Right ventricle 4 CHAMBERED HEART! Left atrium Right atrium R L

Left ventricle Left pulmonary vein Thoracic (descending) aorta Azygous vein Right atrium Right ventricle Right pulmonary vein Left atrioventricular orifice Right atrioventricular orifice Interventricular septum 4 CHAMBERED HEART! R L LA Left atrium

Left pulmonary vein Right pulmonary veinAzygous vein Esophagus Thoracic (descending) aorta 5 CHAMBERED HEART? Left atrium Right atrium Left ventricle Right ventricle * - AORTA - arising from Vestibule R L

Left main bronchus Superior vena cavaAscending aorta Azygous vein RIGHT VENTRICLE EXTENDS TO LEFT Right ventricle RV R L

Left pulmonary artery Right pulmonary artery Carina at tracheal bifurcation Thoracic (descending) aorta Ascending aorta Superior vena cava PULMONARY TRUNK BRANCHES Y Y Right ventricle to Pulmonary Trunk R L

Arch of aorta Superior vena cava Trachea Esophagus R L

Superior vena cava Spinal cord Left subclavian artery Scapula Trachea Esophagus R L

Left brachiocephalic vein Trachea Esophagus Left common carotid Right lung Right brachiocephalic vein Left subclavian artery Brachiocephalic trunk LEFT BRACHIOCEPHALIC VEIN CROSSES ANTERIORLY R L

Summary - Orientation of heart in CT and MRI is complex; rarely appears to have 4 chambers. 1. Position and Orientation of heart - Heart is rotated and tilted so Right Ventricle is anterior and inferior; this makes functional sense; as a result, Left Atrium is located in midline and receives blood symmetrically from Pulmonary Veins (low pressure). 2. Sequence of Structures Inferior to Superior - Pulmonary Veins, Pulmonary artery, Arch of Aorta. 3. Pulmonary artery - arises from Conus arteriosus (Infundibulum) of Right Ventricle; ascends toward left and crosses anterior to Aorta; Pulmonary artery then bifurcates (appears Y shaped in axial CT and MRI). 4. Aorta - arises from Left Ventricle and first courses in middle of heart (Heart appears to have 5 chambers in axial CT and MRI at this level). 5. Order of Structures in Superior Mediastinum - Veins (R and L Brachiocephalic) are anterior to Arteries (Brachiocephalic, L Common Carotid, L Subclavian) arising from Arch of Aorta.

REMEMBER: ANATOMICAL DETAILS ARE COMPLEX AND DIFFICULT TO LEARN BUT PATIENTS CAN DIE FROM 'MINOR DETAILS' OF ANATOMY.