Middle Mesiastinum Flashcards
how is the middle mediastinum divided?
Into a superior/ inferior
only the inferior is further divided in an anterior, middle, and posterior portions
what are the contents of the middle mediastinum?
- Heart
- Pericardium
- Root of Great Vessels
- Root of the lungs
- Phrenic nerves (and accompanying pericardiophrenic vessels)
where are the phrenic nerves located with respect to the lungs? where is the vagus nerve located with respect to the lungs?
phrenic = ANTERIOR to the root of the lungs vagus = POSTERIOR to the root of the lungs
what is the pericardium?
a sac enclosing the heart and the roof of the great vessels
what is the fibrous pericardium?
an outer layer of dense connective tissue that attaches to the superior surface of the diaphargm
what are the 3 most important things about the location of the fibrous pericardium?
- it is located superior to the most superior aspect of the heart, and eventually fuses with the adventitia of the great vessels
- it does NOT lie directly on the surface of the heart
- it is continuous below the heart and fuses with the central tendon of the diaphragm
how is the serous pericardium divided?
into parietal and visceral layers
where is the parietal pericardium located?
internal to the fibrous pericardium
where is the visceral pericardium located? what is an alternative name for it?
lines the heart (known as the epicardium)
what does the reflection of the serous pericardium onto the great vessels result in?
the transverse and oblique sinuses
what is a reflection?
change in direction ie change in direction of the serous pericardium leads to sinuses
where is the transverse sinus located with respect to the heart, great vessels, pulmonary vessels?
posterior to the heart
inferior to the great vessels
superior to the pulmonary vessels
where is the oblique sinus located?
posterior to the heart, BETWEEN the right and left pulmonary veins
what is the significance of the pericardium fusing with the central tendon of the diaphragm?
is causes the heart to move UP with EXHALATION and
DOWN with every INHALATION
what is the only layer of the pericardium that actually comes in contact with the surface of the heart?
visceral pericardium (epicardium)
what part of the heart takes up most of the anterior surface area when the heart is in the sternocostal position?
right ventricle
what part of the heart take up most of the posterior surface area of the heart when it is in the sternocostal position?
left ventricle
what separates the right atrium from the right ventricle?
coronary (atrioventricular) groove
what separates the right and left ventricles?
interventricular septum
where is the apex of the heart located/directed? where is located with respect to the base? to the left ventricle?
downward and to the left about 45 degrees from the median plane; it is more anteriorly located than the base.
IT IS THE MOST INFERIOR POINT ON THE HEART (usually marks the level of the left ventricle)
where is the base of the heart located? what does it include?
most SUPERIOR surface of the heart; contains the SVC,, aorta, pulmonary trunk
what is an area of ausculation?
exact position on the anterior aspect of the thoracic wall that you place a stethoscope on to listen to heart valves best sound transmission
where would a stethoscope be placed to hear the pulmonary valve?
in the 2nd left intercostal space, close to the sternum
where would a stethoscope be placed to hear the aortic valve
2nd right intercostal space close to the sternum
where would a stethoscope be placed to hear the mitral valve
left 5th intercostal space at the mid-clavicular line (over the apex of the heart)
where would a stethoscope be placed to hear the tricuspid valve?
just to the left of the lower part of the sternum near the 5th intercostal space
are the areas of auscultation located at the actual anatomical location of the valves?
no
where does the right atrium receive blood from?
the superior vena cava from above and the inferior vena cava from below at the sinus of the venae cavae (on the posterior aspect)
what is the sulcus terminalis cordis? where is it located?
a groove which separates the sinus venarum from the rest of the atrium; located at the posterior aspect of the right atrium (external anatomy)
what is the texture of the sinus venae cavae? where is it located?
smooth portion; located on the posterior aspect of the right atrium, at the entrance of the vena cava (SVC/IVC entrance)
what is the crista terminalis?
separates the sinus venae cava from the rest of the right atrium;
It is the internal representation of the sulcus terminalis
what are the pectinate muscles?
rough muscles ridges that covers the anterior side of the right atrium
what is the fossa ovalis?
a depression which represents the remains of the embryonic foramen ovale which connected the right and left atria for communication
what is the primary venous drainage of the heart
coronary sinus
what is the conus arteriosus? (infundibulum) where is it located?
smooth walled portion of the right ventricle that represents the junction between the right ventricle and the pulmonary trunk; located on the superior right ventricle
what are trabeculae carne? where are they located?
muscular projections located in the inferior portion of the right ventricle
what are the muscular ridges/projections of the right atrium called? right ventricle?
right atrium = pectinate muscles
right ventricles = trabeculae carnae
what are the components of the tricuspid valve (right AV valve)
- papillary muscles
- chordae tendinae
- valve cusps (anterior, posterior, septal)
3 cusps each is associated with a papillary muscle (respective) that is attached to the valve via chordae tendinae
what is the only part of the cardiac conduction system that is visible to the naked eye?
septo-marginal trabecula (the moderator band)
what are valvules?
non-functional valves
what is the conus arteriosus? (infundibulum); where is it located? what is it’s texture?
junction of the right ventricle with the pulmonary trunk; smooth walled portion on the superior aspect of the internal right ventricle
what are trabeculae carne?
muscular ridges/projections in the inferior portion of the right ventricle
what are the internal muscular projections of the right ventricle called? right atrium?
right ventricle = trabeculae carne
right atrium = pectinate muscles
what are the components of the tricuspid valve?
- 3 valve cusps (anterior, posterior, septal)
- papillary muscles (respective to each cusp)
- chordae tendinae that connects the cusps to the papillary muscle
what is the only part of the cardiac conduction system that is visible to the eye?
septo-marginal trabecula (moderator band)
where does the left atrium receive blood from? what type of blood is received in the left atrium?
4 pulmonary veins:
superior/inferior left pulmonary veins + superior/inferior right pulmonary veins
oxygenated blood
the wall of which ventricle (left/right) is thicker? why?
left; because it pumps blood to the entire body via high resistance vessels while the right ventricle only pumps blood to the lungs
what is found internally in the left ventricle?
trabeculae carne and TWO large papillary muscles with associated chordae tendinae
what valve is found between the left atrium and left ventricle?
bicuspid/mitral/left AV
what are the two components of the interventricular septum? how is it divided?
membranous component = superior 1/3
muscular component = inferior 2/3
From which anatomical direction are all 4 chambers of the heart visible?
mid-sagittal
which part of the interventricular septum is more prone to defects? why?
membranous portion becuase it is thinner and attaches to the tricuspid valve via the “septal cusp”
Describe blood flow during diastole
bood flow in from the atrium to the ventricle = the AV valves are open and the ventricles fill with blood via PASSIVE movement (no heart contraction)
describe blood flow during systole
chordae tendinae (attached to the ventricular surface of the AV valve cusps and papillary muscles) cause the papillae muscle to contract downward and pull in slack of chordae tendenae so that the cusps cannot open up
why are papillary muscles necessary (due to the specific manner in which the heart contracts)
the ventricles contract in an upward spiral movement so that the length of the ventricular chamber shortens and the floor of the ventricle moves towards the roof; the papillary muscles are needed to pull down and close off the AV valves during this movement
what is the function of the AV valves?
to prevent blood from flowing back to atrium from ventricles during SYSTOLE (both ventricles contract)
what is the biscupid valve made up of?
aka mitral valve
made up of 2 valve cusps (anterior /posterior), respective papillae muscle, and chordae tendonae
what is the function of the semilunar valves?
prevent the backflow of blood during diastole
what are the semilunar valves?
aortic + pulmonary valves
how many cusps does the aortic valve have? what are they called?
3: right, left POSTERIOR
how many cusps does the pulmonary valve have? what are they called?
3; right, left, ANTERIOR
why do the semilunar valves close?
due to back pressure of blood in the vessel after SYSTOLE (so that they are closed during DIASTOLE)
where does right coronary artery arise from?
the right aortic sinus
where is the right coronary artery located?
emerges between the pulmonary trunk and right atrium and follows the AV or coronary groove
How man branches does the right coronary artery have? what are they called/where do they travel to?
4 branches; “At Night Margaret Posts (on facebook)”
- Atrial branch to the right trium
- Nodal artery to the SA node (often a branch of atrial artery)
- Marginal artery (on right margin of the heart)
- posterior interventricular branch (in the posterior interventricular sulcus)
where does the left coronary artery arise from?
the left aortic sinus
what is the course of the left coronary artery?
courses between the pulmonary trunk and left atrium
How many branches does the left coronary artery have? where are they located?
2;
- Anterior Interventricular branch located in the anterior interventricular sulcus
- Circumflex branch located in the coronary groove (posterior heart); gives rise to the Left Marginal Branch
Where is the coronary sinus located?
in the posterior porion of the AV groove between the left atrium and left ventricle
what veins does the coronary sinus receive blood from?
“Great Man, Small Penis”
- great cardiac vein
- middle cardiac vein
- small cardiac vein
- posterior cardiac vein
where is the great cardiac vein located? with anything else?
in the anterior interventricular sulcus with the anterior interventricular artery
where is the middle cardiac vein located? with anything else?
in the posterior interventricular groove with the posterior interventricular artery
where is the small cardiac vein located? with anything else?
in the right margin of the heart with the marginal artery
where is the posterior cardiac vein located? with anything else?
with the left marginal artery
where do the anterior cardiac veins drain into? what is the course/path? what do they drain?
drain DIRECTLY into the right atrium * DO NOT ENTER THE CORONARY. SINUS;
arise on the anterior wall of the right ventricle, bride across the coronary sulcus and end in the right atrium;
drain the myocardium of the right ventricle directly
What is the function of the conduction system of the heart?
connects “pacemaker” regions of the heart with cardiac muscle in order to all of for synchronous contraction of the heart
Where is the Sino-Atrial node located? is it visible to the naked eye?
located at the junction of the superior vena cava and the right atrium at the end of the cirsta terminalis; NOT VISIBLE TO THE EYE
were is the Atrioventrcular Node located? is it visible to the naked eye?
located in the lower part of the interatrial septum just above the opening of the coronary sinus; NOT VISIBLE TO THE EYE
Where is the atrioventricular bundle (bundle of His) located/pathway?
passes from AV node beneath the membranous portion of the septum to the muscular septum; then bifurcates at the muscular septum into the right and left Crurua of the AV bundle
what is the pathway of the two crura? are they visible to the naked eye?
LEFT: flows to the left ventricle and coordinates its contraction
RIGHT: passes through the septo-marginal trabeculae to the anterior papillae muscles of the right atrium CAN SEE JUST THE THE RIGHT!!
what regulates the SA/AV nodes?
autonomic nerves
