Lecture 19: Middle Mediastinum Flashcards
Contents of the middle mediastinum
pericardium (the envelops phrenic nerves, heart, root of aorta, distal segment of the superior vena cava, pulmonary veins, inferior vena cava, pulmonary trunk, right pulmonary arteries, and right and left main stem bronchi)
What are the components of pericardium
Visceral and partietal pericardium create the pericardial cavity contains serous fluid- derived from intraembryonic coelomic space
Pericarditis
inflammation of the pericardial sac- can result in fluid accumulation in pericardial cavity which impedes the motion of the heart. Procedure to remove fluid is pericardiocentesis
Cardiac tamponade
The accumulation of fluid in the pericardial cavity that impedes the motion of the heart caused by inflammation of the pericardial sac
What are the two pericardial sinuses
oblique and tranverse
Transverse sinus
connects the right and left sides of the cavity, and separates the outflow tracts (aorta and pulmonary trunk) from the inflow tract (superior vena cava)
Oblique sinus
Inverted U-shaped on the dorsal to the left atrium between the pulmonary veins and superior vena cava
Clinical significance of these sinuses?
??
Are the right and left sides of the heart on the left and right sides of the thorax
no
What is the orientation of the heart after rotation during development
right ventricle is anterior and positioned to the left along with the left ventricle
What region of the heart comprises the base?
the posterior aspect
What region comprises the apex of the heart
left ventricle (the inferiolateral tip)
Where is the apex of the heart normally positioned?
5th intercostal space
Coronary sulcus
encircles the heart and discerns between the atrium and ventricles
Interventricular sulci
separates the two ventricles (one on the anterior and posterior)
Anterior surface of the heart
mainly right ventricle with a little right atrium
Posterior surface of heart
Left atrium with smaller portions of the left ventrical and right atrium
Diaphragmatic surface of hear
mostly right ventricle with a little contribution by the left ventricle
Superior boarder of heart
roots of aorta, pulmonary a., and superior vena cava
Where are the strongest heart sounds and why
left to the sternum because the heart is usually slightly left of the midline
Dextrocardia
when the heart is slightly right to the midline instead of left and results in the strongest heart sounds being to the right of the sternum
How does some endocardial tissues receive nourishment
via direct diffusion of oxygen and nutrients from blood within the cardiac chambers
Where do the coronary arteries and veins travel
beneath the epicardium (visceral peritoneum embedded in fat
What aortic sinus is the right coronary artery originated in?
right aortic sinus (of Valsalva)
What does the right coronary a. supply
Right atrium, right ventricle, and SA node
What are two important branches given off by the right coronary a.
nodal a. (posterior to right auricle) and right marginal a. (descending right cardiac border)
What does the left coronary a. supply
much of the left ventricle, small part of right ventricle, ventricular septum, and part of the left atrium
Where does the left coronary a course
arises from aorta and passes posterior to pulmonary trunk
Where does the left coronary a. branch
coronary sinus
What are the two branches of the left coronary a.
left anterioventricular branch and circumflex blanch
What gives rise to the left marginal a.
the circumflex artery
Where does the circumflex a. travel
in the coronary sulcus
What is the inter ventricular septum primarily supplied by?
branches of the left coronary a.
What does the nodal branch supply
right atrium and SA node (sin-atrial node)
What does the right marginal a. supply?
Anterior wall of the right ventricle
What does the posterior inter ventricular a. supply?
Posterior wall of the right ventricle and the posterior part of the inter ventricular septum
What does the anterior inter ventricular a supply?
anterior left ventricle, most of the anterior inter ventricular septum, apex
What does the left marginal a. supply?
Lateral wall of the left ventricle
What does the circumflex branch supply?
Posterior wall of the left atrium and left ventricle
Describe how we know if a heart is right dominant
The posterior inter ventricular a is derived from the right coronary a. and the right coronary crosses to the left side to supply the left ventricularwal and posterior inter ventricular septum.
Left commence?
Posterior interventricular a. derived from the left coronary a.
Codominence? ***
coronary arteries are balance?
ischemia (minor)
insufficicent coronary blood flow, leads to angina pectoris (chest pain)
ischemia (major)
dysrhythmias or cardiac arrest
cause of ischemia
arteriosclerosis
What are the two systems used for venous drainage of the heart
cardiac veins and thebesians veins
Great cardiac v. location
begins at the cardiac apex, follows the anterior inter ventricular sulcus to the base of the ventricles then passes to the left in the coronary sinus
What does the great cardiac v. drain
Left artrium and both ventricles
Middle cardiac v. location
starts at the cardiac apex rises in the posterior inter ventricular sulcus and ends in the coronary sinus
What does the middle cardiac v. drain
posterior ventricular surface
Anterior cardiac v. locations
span the anterioventricular groove and drain directly into the right atrium
What does the Anterior cardiac v. drain
from the upper surface of the right ventricle
thebesian veins location
begin in the myocardium and empty into the cardia atria or ventricles.
What empties into the right atrium
superior and inferior vena cava
crista terminalis
raised ridge on the inner arterial wall that demarcates its anterior and posterior segments
Where is the SA node found?
where the crust terminals meets the perimeter of the superior vena cava oriface
Inforeior vena cava valve
semi-lumar shaped tissue
Fossa ovalis location- embryonic remenent
septal wall of right atrium- site of fetal foramen ovale
Valve of coronary sinus is what shape?
crescent shaped
What are the 3 leaflets of the tricuspid valves
Anterior, Posterior, and Septal
Position of the anterior and posterior leaflets
Anterior-Superior
Posterior- Inferior
Purpose of chord tendinae
the tether the leaflets to the ventricular wall and help keep the valve leaflets closely approximated during systole(when pressures within the ventricular chambers are highest) this prevents blood from leaking from the ventricle back into the arterial chamber
What two papillary muscles does the posterior ventricle have
anterior and posterior
Where does the moderator band pass?
Passes from the inferior portion of the septal wall to the base of the anterior papillary muscles.
What are the 3 cusps of the pulmonary valve
anterior left and right
What does the pulmonary trunk branch into
right and left pulmonary arteries
Ligamentum arteriosum
connects the pulmonary trunk to the ascending aorta. Remnant of ductus arteriosus
What lung will the right pulmonary artery go to
right
Are the pulmonary arteries posterior or anterior to the mainstream bronchi?
Anterior
What are the branches of the right/left pulmonary a
Upper and lower (to supply their respective lobes)
Position of the anterior and posterior leaflets of the mitral valve
Superior and inferior respectively
Mitral vale
Connects the left atrium to left ventricle and is a bicuspid valve
How many cusps does the aortic valve have and what are they called?
3- called right and left coronary cusp and non-coronary cusp
What are aortic sinuses of Valsalva
3 small dialations called the right and left coronary and non-coronary
Where are the chemoreceptors located in the heart and what do they do?
Located in the wall of the ascending aorta they monitor pH and CO2 in the blood.
Why are the sounds of valves hear at a site distant from their location
because anatomically they lie close to one another and and posterior to the sternum
Where is the aortic valve heard?
right 2nd intercostal space
Where is the pulmonic valve heard?
Left second intercostal space
Where is the mitral valve heard?
left 5th intercostal space at midclavicular line
Where is the tricuspid valve heard?
to the left of the xiphosternal junction
What does the cardiac cycle consist of
diastole and systole
diastole
ventricular filling
systole
ventricular emptying
Diastole begins with…
the closure of the aortic and pulmonic valves. Blood now flows from the right atrium across the tricuspid valve to the right ventricle and from the left atrium across the mitral valve into the left ventricle
Systole begins when…
When the ventricles are full. The ventricular muscles begin to contract which forces the tricuspid valves of the aorta and pulmonary trunk to open
Lub sound of hear
caused by the vibration of blood in the ventricular chambers as systole begins and the atrioventricular (A-V) valves shut
dub sound of heart
caused by vibration of blood from the closure of the aortic and pulmonary valves at the end of systole
What is the pacemaker of the heart
SA node (At the junction of crust terminalis and superior vena cava in right atrium)
Where is the atrioventricular node (AV) located?
near the base of the intertribal septum along opening of coronary sinus
Where does the atrioventricular bundle of his run and divide into?
The atrioventricular bundle of his exits the AV node and travels in the inter ventricular septum where it divides into right and left bundle branches
Right bundle branch (traveling distance)
travels inferiorly in the septum to enter the moderator band and terminate in the base of the anterior papillary muscle of the left ventricle
Left bundle branch
Also courses in the inter ventricular septum which terminates in the base of each papillary muscle of the left ventricle
Both the heath receive sympathetic or parasympathetic innervation
both- also receives visceral sensory nerves
Where are the sympathetic ganglion that innervate the heart located
Spinal cord segments T1-T6
