Anterior and Middle Mediastinum Flashcards
what are the divisions of the mediastinum
superior and inferior
inferior further divided into anterior, middle and posterior
where is the division between the superior and inferior mediastinum
imaginary line - transverse thoracic plane
where does the transverse thoracic plane run between
sternal angle to IVD between T4/T5
what is this boundary of the anterior mediastinum: anterior
body of sternum
what is this boundary of the anterior mediastinum: posterior
fibrous pericardium
what is this boundary of the anterior mediastinum: superior
transverse thoracic plane
what is this boundary of the anterior mediastinum: inferior
diaphragm
what are the 4 boundaries of the anterior mediastinum
body of sternum
fibrous pericardium
transverse thoracic plane
diaphragm
what is found in the anterior mediastinum
loose connective tissue
fat
lymphatics
why is the anterior mediastinum larger in children
contains thymus
where is the thymus located
organ of superior mediastinum that often extends into anterior mediastinum
what are the boundaries of the middle mediastinum
bounded on all sides by pericardial sac
what is the middle mediastinum
heart, pericardium and roots of great vessels
give 3 structures that are adjacent to the middle mediastinum
great vessels
phrenic nerves - become assoc. with fibrous pericardium
lung root structures
the right phrenic nerve passes over what part of the heart and become associated with pericardium
right atrium
the left phrenic nerve passes over what part of the heart and become associated with pericardium
left atrium and ventricle
the fibrous pericardium is a tough connective tissue sac that blends superiorly with what
tunica adventitia of great vessels as they enter and leave the heart
inferiorly the fibrous pericardium is continuous with what
central tendon of diaphragm
what proportion of the heart is on the left of the midline
2/3 on left
1/3 on right
what are the 2 types of pericardium
fibrous and serous
what is the parietal serous pericardium
lines the pericardial sac
what is the visceral serous pericardium
serous pericardium reflected over roots of great vessels onto surface of heart
(shiny surface on heart)
what is found deep to the visceral serous pericardium
substantial amount of fat
what is most superficial in arrangement of pericardium
tough fibrous pericardium forming pericardial sac
what is another name for visceral serous pericardium
epicardium
how is friction reduced when the heart beats to prevent damage to surface of muscle of heart
fluid produced by serous pericardium between the 2 layers of serous pericardium
name of muscle layer of heart
myocardium
name of lining of chambers of heart
endocardium
what is the name of the 2 pericardial sinuses of the heart
transverse and oblique
how does the transverse pericardial sinus arise
the heart develops from a simple tube with an inflow and outflow end. as it develops it folds in on itself and brings 2 ends closer creating a narrow channel between inflow and outflow vessels of the heart
if you place your finger in the transverse pericardial sinus, the outflow vessels are ____ to finger
outflow - anterior
if you place your finger in the transverse pericardial sinus, the inflow vessels are _____ to finger
inflow - posterior
(OsteoArthritis Is Painful)
where is the oblique pericardial sinus
space posterior to heart - slide hand underneath heart and behind so fingers are posterior to left atrium - pulmonary veins on either side
base of heart
left aftrium (mainly)
right border of heart
right atrium
inferior border of heart
right ventricle
apex of heart
left ventricle
left border of heart
left ventricle and left auricle
superior border of heart
right and left atria and auricles
when you look anteriorly at the heart what do you mostly see
right side
what are the extensions of the atria called
auricles
what are the branches of the aorta
(R+L coronary arteries)
brachiocephalic trunk
left common carotid
left subclavian
the atrioventricular/coronary groove separates what
RA and RV
what is found in the atrioventricular/coronary groove
right coronary artery
what is found in the anterior interventricular groove
left anterior descending
a.k.a. anterior interventricular artery
describe the path of the IVC
pierces the diaphragm at T8 and immediately enters the inferior aspect of the right atrium
what vessel leaves the right ventricle
pulmonary trunk
what are you looking at mostly when you look at heart from a postero-inferior view
mostly left side
what are the 5 surfaces of the heart
anterior (sterno-costal)
posterior (base)
right pulmonary
left pulmonary
diaphragmatic (inferior)
what forms the anterior (sterno-costal) surface of the heart
right ventricle
what forms the base (posterior) surface of the heart
left atrium
what forms the right pulmonary surface of the heart
right atrium
what forms the left pulomonary surface of the heart
left ventricle
what forms the diaphragmatic surface of the heart
left and right ventricles
the ligamentum arteriosum is a remnant of what
ductus arteriosus - after birth will close and become a fibrous structure
what is the function of the ductus arteriosus
allows communication between the aorta and pulmonary trunk so it bypasses lungs during foetal life
describe the left recurrent laryngeal nerve in relation to the ligamentum arteriosum
left recurrent laryngeal nerve runs posterior to ligamentum arteriosum
what is the first branch of the RCA
SA nodal branch
where is the SA node
in the wall of the RA
where does the RCA travel
in right AV groove
gives off branches to supply RA and RV
before turning onto inferior and posterior surface of heart, what branch does the RCA give off
right marginal
where does the right marginal run
right marginal runs along inferior border of heart (RV)
RCA continues on the inferior surface of heart in the ____ groove and gives off what small branch
Atrioventricular groove
AV nodal branch to supply AV node in wall of RA
how does the RCA terminate
gives posterior IV artery which runs in posterior IV groove between left and right ventricle
name the branches of the RCA
SA nodal
right marginal
AV nodal
posterior IV
the LCA is shorter/longer than RCA
shorter
the LCA quickly terminates as what 2 branches
circumflex and anterior interventricular artery (LAD)
where does the Anterior interventricular artery (LAD) run
down anterior aspect of heart in the IV groove between right and left ventricle
what is the name of the branch given off by anterior interventricular artery
diagonal branch
where does the diagonal branch run
runs across the surface of LV
what is the course of the left circumflex artery
continues onto the posterior aspect of heart running in left AV groove between LA and LV
what branch does the circumflex artery give before passing onto posterior surface of heart
left marginal
where does the left marginal artery run
along left border of heart
after giving off the marginal branch, what does the circumflex do
continues in the AV groove and ultimately anastomoses with RCA
what are the branches of the LCA
circumflex
- marginal
LAD
- diagonal
give 2 examples of variation in coronary arteries
- SA nodal branch and posterior IV artery can sometimes come from circumflex artery
- diagonal artery not always present
what is the AV bundle
part of electrical component of heart
where is the AV bundle found
within IV septum
where does the AV bundle receive blood supply from
LCA
what does the RCA supply
right atrium
most of right ventricle
SA node (usually)
AV node
posterior 1/3 of IV septum
part of left ventricle
what does the LCA supply
left atrium
most of left ventricle
anterior 2/3 of IV septum
AV bundle
part of right ventricle
where is the coronary sinus located
swollen venous structure on the posterior surface of the heart between LA and LV
cardiac veins drain to the coronary sinus except …
anterior cardiac veins
what do the anterior cardiac veins drain and where do they drain to
wall of right atrium
drain directly to RA
where is the great cardiac vein found
first part (anterior interventricular vein) found in anterior IV groove
second part runs around left side of heart to reach coronary sinus
the great cardiac vein runs alongside …
AIVA (LAD)
describe the course of the great cardiac vein
travels in the anterior IV groove then curves round the left border of the heart to reach posterior surface of heart where it drains into coronary sinus
what is the main tributary to the coronary sinus
great cardiac vein
where is the middle cardiac vein located
in the posterior IV groove
what does the middle cardiac vein run alongside
posterior IV artery
where is the small cardiac vein found
on wall of RV
what does the small cardiac vein run alongside
right marginal artery
what is the course of the small cardiac vein
runs along wall of RV with right marginal artery then wraps around onto inferior and posterior surface to empty into coronary sinus
the left marginal vein runs with
left marginal artery
what does the posterior ventricular vein drain
posterior wall of LV
what does the oblique vein of LA drain
wall of LA
where does the coronary sinus open
RA
what are the 2 areas of the internal wall of the RA
musculi pectinati
sinus venarum
what are the musculi pectinati
muscular ridges in walls of atria/auricles
what is the sinus venarum
smooth area that connects entrance of SVC above with entrance of IVC below
what is the crista terminalis
pronounced ridge separating the sinus venarum and the muscular wall
the fossa ovalis is a remnant of what
foramen ovale
what was the purpose of the foramen ovale
allowed communication between the RA and LA during development
what does the fossa ovalis look like
small dome shaped depression on interatrial wall
what other landmark can be seen in RA
opening of coronary sinus
blood flows from RA to RV through what valve
tricuspid
where is the tricuspid valve found
right AV canal
what are the structures that anchor the tricuspid valve to the muscular projections of the ventricular wall
chordae tendineae
what are the muscular projections of the ventricular wall called
papillary muscles
the tricuspid valve will have how many papillary muscles
3
what is the structure that is only found in the RV that extends from the IV septum towards the anterior papillary muscle
moderator band
what is the function of the moderator band
will carry part of conducting system of heart
what is the name of the muscular ridges in the RV wall
trabeculae carneae
blood flows from the RV to the lungs via the ____
pulmonary trunk and pulmonary arteries
through pulmonary valve (semilunar)
describe the walls of the LA
smooth and featureless
does have left auricle as an extension
what is the name of the muscular ridges in the area of the auricle in LA
musculi pectinati
blood flows from LA to LV through the ____ valve
bicuspid
what is another name for the bicuspid valve
mitral
how many papillary muscles will be seen in the LV
2
what connects the valve cusp edges to the papillary muscles
chordae tendineae
why is the wall of the LV thicker than that of the RV
needs to produce higher pressure to pump blood around body
what is the name of the muscular ridges in the walls of the LV
trabeculae carneae
blood pumped from LV to aorta through ___
aortic valve (semilunar)
pulmonary arteries carry what kind of blood
deoxygenated
what are the 2 types of heart valve
semi lunar and cuspid
where are the semi lunar valves found
base of aorta and pulmonary trunk
in low pressure the semilunar valves are
closed
semilunar valves open in response to
high pressure as ventricles contract
what causes the semilunar valves to close
as heart relaxes blood falls back towards ventricles and trickles between valve cusp and vessel wall filling the space and forcing the cusps closed
this back flow of blood to the valves also ensures what
blood goes to coronary arteries
how are coronary arteries filled
under low pressure by backflow of blood when wall of ventricle is relaxed
where are the cuspid valves found
between atria and ventricles
in high pressure, the cuspid valves are
closed
the cuspid valves are open when
ventricles are relaxed and blood flows freely from atria to ventricles then atria contract and blood forced into ventricles
when the ventricular pressure increases the cuspid valves will
close
how is prolapse of the cuspid valves prevented
chordae tendineae and papillary muscles hold the leaflets in place - papillary muscles contract at same time as ventricle
during ventricular diastole the cuspid valves are ____ and semilunar valves are ___
ventricular diastole - cuspid valves open, semilunar valves close
during ventricular systole, the cuspid valves are ____ and semilunar valves are ___
ventricular systole - cuspid valves are closed, semilunar valves open
semilunar valves have how many leaflets
3
aortic (Right left and posterior)
pulmonary (right left and anterior)
what part of fibrous skeleton supports cuspid valves
rings
what part of fibrous skeleton supports semilunar valves
coronets
what are 2 functions of the fibrous skeleton of the heart
support
electrical insulation between atria and ventricles
why does the transmission of electrical signals need to be delayed from atria to ventricles
so that atria contract together but before ventricles
how does the heart regulate its own heart rate
SA node
where is the SA node found specifically
within wall of RA
- located in upper part of crista terminalis adjacent to entry of SVC
SA node is located adjacent to what vessel entrance
SVC
where do signals from SA node go
through wall of RA and into wall of LA so atria contract at same time
also picked up by AV node
where is the AV node located
lower part of interatrial septum
what is the function of the AV node
transmits the signal from the SA node down to the ventricles via the AV bundle
the AV bundle divides into what
right and left bundle branches which give off many distributary branches into the wall of the ventricles
some of the fibres of the RBB will travel via the _____ ____
moderator band
what is the purpose of the moderator band (septomarginal trabecula)
ensures that the anterior papillary muscle and anterior part of wall of RV contract at same time as rest of walls of ventricles
what is another name for the moderator band
septomarginal trabeculae
SA can function without external influence but does get autonomic innervation from …
cardiac plexus
what is the parasympathetic innervation of the heart
vagus nerve (CN X) - postsynaptic parasympathetic cell bodies (intrinsic ganglia) are located in the atrial wall and interatrial septum near the SA and AV nodes
parasympathetic stimulation does what to the heart
decrease heart rate
decrease force of contraction
constrict coronary arteries
sympathetic stimulation does what to the heart
increase HR
increase force of contraction
dilate coronary vessels
what does sympathetic stimulation of the heart come from
T1-T5/6 spinal levels
- cervical and superior thoracic paravertebral ganglia (sympathetic chain)
