middle mediastinum

Question 1

where are the boundaries of the middle mediastinum?

Answer 1

• anterior = anterior pericardium
• posterior = posterior pericardium
• lateral = mediastinal pleura
• inferior = diaphragm
• superior = transverse thoracic plane (T4/5)

Question 2

what is contained in the middle mediastinum?

Answer 2

• heart & pericardium
• ascending aorta
• pulmonary trunk & arteries
• pulmonary veins
• nerves

Question 3

where does the deoxygenated blood flow through the heart?

Answer 3

right atrium and right ventricles

Question 4

where does the oxygenated blood flow through the heart?

Answer 4

left atrium and left ventricle

Question 5

where does the oxygenated blood leave the ventricle?

Answer 5

via the aorta

Question 6

what are the different branches of the aorta?

Answer 6

• ascending
• arch
• descending thoracic
• descending abdominal

Question 7

how does deoxygenated blood leave the heart?

Answer 7

via the pulmonary trunk

Question 8

where does oxygenated blood enter into from the lungs?

Answer 8

into the left atrium

Question 9

what type of blood do the superior and inferior vena cava have?

Answer 9

deoxygenated blood

Question 10

what are the 2 regions of the right atrium?

Answer 10

• sinus venarum (smooth walled)

- pectinate muscle

Question 11

where does deoxygenated blood flow into the right atrium from?

Answer 11

• superior vena cava
• inferior vena cava
• coronary sinus

Question 12

where does oxygenated blood flow into the left atrium from?

Answer 12

pulmonary veins

Question 13

what are the 2 semilunar valves of the heart?

Answer 13

• pulmonary valve

- aortic valve

Question 14

what are the 2 atrioventricular valves of the heart?

Answer 14

• tricuspid valve

- bicuspid (mitral) valve

Question 15

what are the 2 cusps of the bicuspid valve?

Answer 15

anterior cusp and posterior cusp

Question 16

what are the 3 cusps of the tricuspid valve?

Answer 16

anterior cusp, posterior cusp and septal cusp

Question 17

what type of cusps does the pulmonary valve have?

Answer 17

• left
• right
• anterior

Question 18

what type of cusps does the aortic valve have?

Answer 18

• left
• right
• posterior

Question 19

what branches from the right cusp?

Answer 19

right coronary artery

Question 20

what branches from the left cusp?

Answer 20

left coronary artery

Question 21

what is the pericardium?

Answer 21

3 layered sac which the heart is suspended in

Question 22

what is the pericardium attached to?

Answer 22

the great vessels superiorly and diaphragm inferiorly

Question 23

what nerve travels over the pericardium?

Answer 23

the phrenic nerve

Question 24

what are the functions of the pericardium?

Answer 24

• protects the heart from overfilling (cardiac distension)

- retains heart in position

Question 25

what are the 2 main layers of the pericardium?

Answer 25

1) serous pericardium (internal)

2) fibrous pericardium (external)

Question 26

what are the 2 layers of the serous pericardium?

Answer 26

a) parietal layer

b) visceral layer (or epicardium)

Question 27

where is the pericardial cavity located?

Answer 27

between the parietal and visceral pericardium

Question 28

what is contained in the pericardial cavity?

Answer 28

small amount of serous fluid to allow for uninhibited movement

Question 29

where do the pericardial sinuses form?

Answer 29

where parietal and visceral layers of the serious pericadium meet

Question 30

what are the 2 pericardial sinuses?

Answer 30

1) transverse sinus

2) oblique sinus

Question 31

where is the transverse sinus located?

Answer 31

between the outflow vessels of the heart and the inflow vessels

Question 32

why can the transverse sinus be used in surgery?

Answer 32

to clamp the outflow of blood from the heart

Question 33

where is the oblique sinus located?

Answer 33

between the pulmonary veins

Question 34

what provides the hearts blood supply?

Answer 34

provided by coronary arteries and veins

Question 35

where are the coronary vessels located?

Answer 35

atrioventricular and interventricular grooves

Question 36

where do the 2 main coronary arteries arise from?

Answer 36

ascending aorta

Question 37

where do functional (potential) anastomoses exist?

Answer 37

between the coronary artery branches

Question 38

what is dominance defined by?

Answer 38

the coronary artery which gives rise to the posterior IV artery

Question 39

how many individuals are RCA dominant and LCA dominant?

Answer 39

RCA dominant = 67%

LCA dominant = 15%

Question 40

where is the SA node located?

Answer 40

close to crista terminalis at the junction between SVC and right atrium

Question 41

what does the SA node initiate?

Answer 41

contraction to impulses spread through atrial wall to AV node via internodal tracts

Question 42

where is the AV node located?

Answer 42

interarterial septum close to the coronary sinus opening

Question 43

what does the AV node do?

Answer 43

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

Question 44

what is the fibrous skeleton?

Answer 44

the framework of 4 fibrous rings of dense connective tissue

Question 45

what does the fibrous skeleton do

Answer 45

provides attachment for atrioventricular and semi-lunar valve and it also forms an electrical insulator between the atria and the ventricles

Question 46

how is the conducting system regulated?

Answer 46

• innervation of the myocardium is regulated by the ANS

- nerves from the ANS destined for the heart enter the cardiac plexus

Question 47

where do the parasympathetic fibres go?

Answer 47

from the vagus nerve and enter the cardiac plexus and then travel to the SA node

Question 48

where do sympathetic fibres go?

Answer 48

from the T1-5 level and enter the cardiac plexus and then travel to the SA node