middle mediastinum Flashcards
where are the boundaries of the middle mediastinum?
- anterior = anterior pericardium
- posterior = posterior pericardium
- lateral = mediastinal pleura
- inferior = diaphragm
- superior = transverse thoracic plane (T4/5)
what is contained in the middle mediastinum?
- heart & pericardium
- ascending aorta
- pulmonary trunk & arteries
- pulmonary veins
- nerves
where does the deoxygenated blood flow through the heart?
right atrium and right ventricles
where does the oxygenated blood flow through the heart?
left atrium and left ventricle
where does the oxygenated blood leave the ventricle?
via the aorta
what are the different branches of the aorta?
- ascending
- arch
- descending thoracic
- descending abdominal
how does deoxygenated blood leave the heart?
via the pulmonary trunk
where does oxygenated blood enter into from the lungs?
into the left atrium
what type of blood do the superior and inferior vena cava have?
deoxygenated blood
what are the 2 regions of the right atrium?
- sinus venarum (smooth walled)
- pectinate muscle
where does deoxygenated blood flow into the right atrium from?
- superior vena cava
- inferior vena cava
- coronary sinus
where does oxygenated blood flow into the left atrium from?
pulmonary veins
what are the 2 semilunar valves of the heart?
- pulmonary valve
- aortic valve
what are the 2 atrioventricular valves of the heart?
- tricuspid valve
- bicuspid (mitral) valve
what are the 2 cusps of the bicuspid valve?
anterior cusp and posterior cusp
what are the 3 cusps of the tricuspid valve?
anterior cusp, posterior cusp and septal cusp
what type of cusps does the pulmonary valve have?
- left
- right
- anterior
what type of cusps does the aortic valve have?
- left
- right
- posterior
what branches from the right cusp?
right coronary artery
what branches from the left cusp?
left coronary artery
what is the pericardium?
3 layered sac which the heart is suspended in
what is the pericardium attached to?
the great vessels superiorly and diaphragm inferiorly
what nerve travels over the pericardium?
the phrenic nerve
what are the functions of the pericardium?
- protects the heart from overfilling (cardiac distension)
- retains heart in position
what are the 2 main layers of the pericardium?
1) serous pericardium (internal)
2) fibrous pericardium (external)
what are the 2 layers of the serous pericardium?
a) parietal layer
b) visceral layer (or epicardium)
where is the pericardial cavity located?
between the parietal and visceral pericardium
what is contained in the pericardial cavity?
small amount of serous fluid to allow for uninhibited movement
where do the pericardial sinuses form?
where parietal and visceral layers of the serious pericadium meet
what are the 2 pericardial sinuses?
1) transverse sinus
2) oblique sinus
where is the transverse sinus located?
between the outflow vessels of the heart and the inflow vessels
why can the transverse sinus be used in surgery?
to clamp the outflow of blood from the heart
where is the oblique sinus located?
between the pulmonary veins
what provides the hearts blood supply?
provided by coronary arteries and veins
where are the coronary vessels located?
atrioventricular and interventricular grooves
where do the 2 main coronary arteries arise from?
ascending aorta
where do functional (potential) anastomoses exist?
between the coronary artery branches
what is dominance defined by?
the coronary artery which gives rise to the posterior IV artery
how many individuals are RCA dominant and LCA dominant?
RCA dominant = 67%
LCA dominant = 15%
where is the SA node located?
close to crista terminalis at the junction between SVC and right atrium
what does the SA node initiate?
contraction to impulses spread through atrial wall to AV node via internodal tracts
where is the AV node located?
interarterial septum close to the coronary sinus opening
what does the AV node do?
continues into AV bundle and divides into the intraventricular septum to travel to left and right ventricles to conduct the impulse to the left and right Purkinje fibres
what is the fibrous skeleton?
the framework of 4 fibrous rings of dense connective tissue
what does the fibrous skeleton do
provides attachment for atrioventricular and semi-lunar valve and it also forms an electrical insulator between the atria and the ventricles
how is the conducting system regulated?
- innervation of the myocardium is regulated by the ANS
- nerves from the ANS destined for the heart enter the cardiac plexus
where do the parasympathetic fibres go?
from the vagus nerve and enter the cardiac plexus and then travel to the SA node
where do sympathetic fibres go?
from the T1-5 level and enter the cardiac plexus and then travel to the SA node
