Mediastinum: Mediastinum contains all structures in the thorax except _____ and ____ , ____ parts of the great vessels, ____, esophagus, thymus, ANS, and ____.  Two divisions: ____ and ____

Mediastinum: Mediastinum contains all structures in the thorax except the lungs and pleura including the heart, thoracic parts of the great vessels, trachea, esophagus, thymus, ANS, and lymphatics.  Two divisions: superior and inferior

Superior Division of Mediastinum: Superior to the ____ from sternal angle to ____ between T4-5.  Contains: ____, great vessels, ____ and ____ nerves, cardiac plexus, trachea, and ____.

Inferior division of mediastinum– 3 Subdivisions:

Anterior:Space between the ____ and ____

Middle:  ____

Posterior:  Thoracic aorta, thoracic duct, ____ and ____ veins, esophagus, ____ plexus, ____ arteries, intercostal veins

Inferior division of mediastinum– 3 Subdivisions:

Anterior:Space between the thoracic wall and pericardium

Middle:  Heart

Posterior:  Thoracic aorta, thoracic duct, azygos and hemiazygos veins, esophagus, esophageal plexus, posterior intercostal arteries, intercostal veins

1. ____:
• Tough external layer protects the heart against sudden overfilling.  
• Fused with fibr0elastic coat of the great vessels entering and leaving the heart. 

1. Serous pericardium:  2 layers – parietal and visceral pericardium
• Parietal fused with the fibrous pericardium.  
• Visceral pericardium is reflected onto the heart where it forms the epicardium.  

1. ____: Space between parietal and visceral pericardium.  Normally contains a thin film of serous fluid.

1. Pericardial cavity: Space between parietal and visceral pericardium.  Normally contains a thin film of serous fluid.

1. Landmarks
• Pericardiacophrenic ligament binds fibrous pericardium to central tendon of the diaphragm.  
• Transverse pericardial sinus:  Posterior to the pulmonary trunk and ascending aorta and anterior to the superior vena cava.  
• Oblique pericardial sinus:  Pocket like recess in the pericardial cavity. 

• Phrenic nerves (C3-C5): Sensory fibers, pain referred to the skin of the ipsilateral supraclavicular region.  
• Sympathetic trunk: Vasomotor.  

• ____ artery, which often accompanies ____ nerve.  Major arterial supply
• ____ vein:  Major venous drainage.

• Pericardiophrenic artery, which often accompanies phrenic nerve.  Major arterial supply
• Pericardiophrenic vein:  Major venous drainage.

Heart:   Slightly larger than a clenched fist, 280-340 grams in men and 230-280 gm in women.  A muscle pump which receives deoxygenated blood from the body to the ____ side and pumps it to the lungs while the ____ side receives oxygenated blood and pumps it to the rest of the body.  

Heart:   Slightly larger than a clenched fist, 280-340 grams in men and 230-280 gm in women.  A muscle pump which receives deoxygenated blood from the body to the right side and pumps it to the lungs while the left side receives oxygenated blood and pumps it to the rest of the body.  

Borders of the heart 

1. Right:  ___, ___, ___
2. Left:  ____ and ____
3. Inferior:  Mainly by ____ and some of ____
4. Superior:  ____, ____, ____, ____
5. Base (posterior aspect): mainly by the ____
6. Apex (inferolateral end): formed by ____

1. Epicardium (outer, formed by serous pericardium)
2. Myocardium (middle, muscle layer)
3. Endocardium (inner, endothelium and subendothelium connective tissue)

1. ____:  Complex framework of dense collagen forming one large ring divided into four smaller rings each of which contains a valve.  The myocardium is built around this fibrous ring which further serves as an electrical insulator. 

1. Fibrous skeleton:  Complex framework of dense collagen forming one large ring divided into four smaller rings each of which contains a valve.  The myocardium is built around this fibrous ring which further serves as an electrical insulator. 

Right Atrium:

1. Smooth posterior wall (____); anterior wall is rough with muscular ridges.  
1. Two landmarks highlight this anatomical distinction.  A shallow vertical groove called the ____ is the external landmark and a vertical crest called the ____ is the internal landmark.

Right Atrium:

1. Smooth posterior wall (sinus of the vena cava); anterior wall is rough with muscular ridges.  
1. Two landmarks highlight this anatomical distinction.  A shallow vertical groove called the sulcus terminalis is the external landmark and a vertical crest called the crista terminalis is the internal landmark.

RA:

The right ____ is a small muscular pouch that projects to the left from the right atrium and overlaps the ascending aorta. 

RA:

1. ____: Translucent oval depression which is the remnant of the embryonic foramen ovale. 

RA:

1. Fossa-ovalis: Translucent oval depression which is the remnant of the embryonic foramen ovale. 

1. ____ (____):  Opening in fossa ovalis (25% of people) results from incomplete closure of the ____, the embryonic communication between the left and right atria which normally closes after birth.  
1. Small ASDs are not usually clinically significant
2. Large ASDs can cause oxygenated blood from the ____ atrium to be shunted to the ____ atrium, overloading both it and the ____ ventricle causing dilation of the pulmonary trunk.

1. Atrial Septal Defect (ASD):  Opening in fossa ovalis (25% of people) results from incomplete closure of the foramen ovale, the embryonic communication between the left and right atria which normally closes after birth.  
1. Small ASDs are not usually clinically significant
2. Large ASDs can cause oxygenated blood from the left atrium to be shunted to the right atrium, overloading both it and the right ventricle causing dilation of the pulmonary trunk.

1. Right Ventricle (RV)
1. Superior left angle tapers into a cone-shaped pouch, the ____ or ____, which leads to the pulmonary trunk.  
1. Interiorly, this region has a smooth wall whereas the remainder is roughened by a number of irregular papillary muscles and muscular ridges (____) giving a course sponge-like appearance. 

RV:

Papillary muscles:  Conical projections distally attached to the ventricular wall and proximally attached to ____ which are themselves attached to the free edges of the tricuspid valve; contracts during ____ to tense the chordae tendineae, preventing the cusps from opening.  

1. Anterior:largest; primarily responsible for ____.
2. Posterior: smaller 
3. Septal:  smallest 

RV:

1. Papillary muscles:  Conical projections distally attached to the ventricular wall and proximally attached to chordae tendineae which are themselves attached to the free edges of the tricuspid valve; contracts during systole  to tense the chordae tendineae, preventing the cusps from opening.  
1. Anterior:largest; primarily responsible for valve closure.
2. Posterior: smaller 
3. Septal:  smallest 

RV:

Prominent trabeculae carneae crosses the ventricle from the septum to the base of the anterior papillary muscle, this is the ____.  Carries the right bundle branch 

Valves

1. Right atrioventricular valve (____ valve), 3 cusps
2. Pulmonary valve:  Lies at the apex of the ____ prevents backflow of blood into RV following systole  

RV:

1. Right atrioventricular valve (tricuspid valve), 3 cusps
2. Pulmonary valve:  Lies at the apex of the conus arteriosus prevents backflow of blood into RV following systole  

RV:

Contraction is primarily of the free anterior wall moving towards the ____.  Blood takes a U shaped path through the ____ to leave via the ____.  

Left atrium:

Long tubular ____ forms the superior part of the left border of the heart.  

Left atrium:

Long tubular left auricle forms the superior part of the left border of the heart. 

Left Atrium

Walls slightly ____ than the right atrium.  Interior mm is smooth except in the ____, which has muscular ridges.  

Left Atrium

Walls slightly thicker than the right atrium.  Interior mm is smooth except in the auricle, which has muscular ridges.

Left atrium

____ can form on the walls of the left atrium which can break off, pass into circulation, and occlude peripheral arteries.  Thrombus that obstructs a vessel is called an ____. 

Left Atrium

1. Superior/anterior part is formed by the ____ which leads to the aorta.  Smooth walls are mainly fibrous.  
2. Interior of remainder is covered with ____ which are finer and more numerous than the RV.  

1. Valves
1. ____ is like the pulmonary valve but cusps are thicker.  Aortic sinuses are formed ____ to each valve by dilation of the wall; prevents the cusps from sticking to the walls of the artery and failing to close.  
2. ____ (or ____) valve, smaller than the tricuspid valve (2 cusps v 3). 

1. Valves
1. Aortic valve is like the pulmonary valve but cusps are thicker.  Aortic sinuses are formed superior to each valve by dilation of the wall; prevents the cusps from sticking to the walls of the artery and failing to close.  
2. Mitral (or bicuspid) valve, smaller than the tricuspid valve (2 cusps v 3). 

____ (___):  common in membranous portion of the septum.  Most common cardiac defect (25% of all congenital heart dz.)

Ventricular septal defect (VSD):  common in membranous portion of the septum.  Most common cardiac defect (25% of all congenital heart dz.)

Right coronary artery (RCA)

1. From the right aortic sinus along the coronary groove between the____ and the ____  inferior to the border of the heart where it gives off a ____ branch that runs towards the apex of the heart.  After giving off this branch, the RCA turns to the left in the posterior part of the ____, enters the posterior ____ groove, gives off its largest branch, the ____ branch.  
2. Descends toward the apex of the heart and anastomoses with the ____ branch of the LCA.
3. Typically supplies: RA, RV, IV septum, AV node, and SA node and bundle.  Variably supplies part of the LA and LV.  

Right coronary artery (RCA)

1. From the right aortic sinus along the coronary groove between the right auricle and the right ventricle  inferior to the border of the heart where it gives off a right marginal branch that runs towards the apex of the heart.  After giving off this branch, the RCA turns to the left in the posterior part of the coronary groove, enters the posterior interventricular (IV) groove, gives off its largest branch, the posterior IV branch.  
2. Descends toward the apex of the heart and anastomoses with the anterior IV branch of the LCA.
3. Typically supplies: RA, RV, IV septum, AV node, and SA node and bundle.  Variably supplies part of the LA and LV.

1. Left coronary artery (LCA)
1. Arises from the left aortic sinus and passes between the ____ and ____ to reach the coronary groove.  
2. Divides into ____ branch and ____ branch.  
1. Larger ____ branch passes along the IV groove to the apex of the heart and anastomoses with the ____ branch of the RCA.  
2. The smaller circumflex branch follows the ____ groove around the left border of the heart to the posterior surface of the heart.  Terminates to the left of the post IV groove.  Circumflex has a ____ branch that follows the left border of the heart. 
3. Typically supplies: LV, LA, and IV septum, including the AV bundle.  Variably supplies: SA and AV nodes.

1. Variations of the coronary arteries
1. In ~ 50% of cases the ____ is dominant as it crosses the left side and supplies the LV wall and septum.  
2. In ~20% of cases the ____ is dominant branching to the right side of the heart.  
3. In 30% of the cases the coronary arteries are balanced.  Some people may have only one coronary artery.  
4. In about 4% of the cases there is a(n) ____ artery (3 vessels). 

Coronary veins

1. Venous return mainly empties into the ____. The ____ receives the great vein at its left side and the middle and small cardiac veins at its right end.  ____ drains venous blood into the right atrium.

Coronary veins

1. Venous return mainly empties into the coronary sinus. The coronary sinus receives the great vein at its left side and the middle and small cardiac veins at its right end.  Coronary sinus drains venous blood into the right atrium.

Coronary veins

1. ____ vein:  Main tributary of the coronary sinus.  Begins near the apex of the heart and ascends in the ____ groove with the ____ artery.  Drains the areas supplied by the LCA.

Coronary veins

1. ____ vein:  Ascends in the posterior IV groove with the posterior IV artery. 

Coronary veins

1. ____ vein: runs in the coronary groove with the marginal branch of the RCA. 
1. Middle and small ____ veins drain most of the heart supplied by the RCA.

Coronary veins

1. Small cardiac vein: runs in the coronary groove with the marginal branch of the RCA. 
1. Middle and small cardiac veins drain most of the heart supplied by the RCA.

Coronary conduction system

1. Specialized for ____ and rapidly ____ through the heart. 

Coronary conduction system

1. ____ node (____ node):  Pacemaker of the heart; 60-100 beats is the normal HR range. 
1. ____ node located at the superior end of the crista terminalis at the junction of the ant/med aspect of the SVC.  
2. ____ node supplied by both divisions of the ANS.  
1. Under resting conditions, the ____ nervous system acts to restrain HR by acting on the  node. 

Coronary conduction system

1. ____ node (____ node):  Located in the interatrial septum. Impulses from both atria converge on the ___ node and then pass to the ventricles.  
1. Impulse slows down in this area to allow maximal ventricular filling, called ____.  

Coronary conduction system

1. ____ (____).  Originates in the AV node and runs through the membranous part of the IV septum.  Only bridge between the atria and ventricles.  This divides into ____and ____ branches.  Each branch permeates deep into the endocardium portion of the ventricles to ensure coordinated contraction of both ventricles

Coronary Innervation

1. The ____ nervous system supplies parasympathetic and sympathetic innervation to the heart.  Both come from the ____ plexus which lies ____ to the bifurcation of the trachea, ____ to the arch of the aorta and ____ to the bifurcation of the pulmonary trunk.

Coronary innervation

1. Stimulation of the ____ nervous system causes increase in HR and force of contraction.  

Coronary innervation

1. Stimulation of the ____ nervous system, via the ____ nerve to the SA Node, slows the HR and decreases the force of contraction.