Middle Mediastinum & Heart

Question 1

what are the structures in the middle mediastinal compartment?

Answer 1

1. pericardium
   
   1. heart
2. phrenic nerves
3. pericardiacophrenic vessels
4. stems of great vessels

Question 2

what is meant by the heart being an “electrico-mechanical” pump?

Answer 2

• electrical: it pumps autonomously
• mechanical: torsion and vavlvds control pressure between chambers

Question 3

pericardium

Answer 3

• double-walled fibroserous sac which surrounds & covers the heart and roots of great vessels
• limits/preventes distension of the hart

Question 4

serous pericardium

Answer 4

• parietal layer: lines inside of fibrous pericardium
• visceral layer: covers outside of heart (epicardium)

Question 5

fibrous pericardium

Answer 5

CT layer outside of the parietal serous layer that forms bulk of pericardial sac

Question 6

What are the layers of the heart?

Answer 6

1. fibrous pericardium
2. parietal layer of serous pericardium
3. pericardial cavity
4. visceral layer of serous pericardium
5. epicardium
6. myocardium
7. endocardium

Question 7

transverse sinus

Answer 7

separates arteries from viens (arteries are anterior while veins are posterior when viewing heart posteriorly)

Question 9

oblique sinus

Answer 9

formed by reflection onto the pulmonary veins

Question 10

what nerves innervate the pericardium

Answer 10

1. phrenic nerves
2. vagus (vagi) nerves
3. sympathetic trunk

Question 11

epicardium

Answer 11

visceral layer of the pericardium–external covering of heart

Question 12

subepicardium

Answer 12

between epicardium and myocardium–contains fat and major vessels to the heart

Question 13

myocardium

Answer 13

oblique fibers (torsion of chambers)

Question 14

endocardium

Answer 14

inner lining layer–composed of endothelium backed by thin CT

Question 15

subendocardium

Answer 15

outside of the endocardium (contains tissues of the conducting system)

Question 16

what is ischemic heart disease?

Answer 16

it is when are of subendocardium (conducting system) is lost; thus loose conductive function of the heart

Question 17

How can you find the apex of the heart?

Answer 17

where left mid-clavicular line meets 5th intercostal space

Question 18

what is the main observation from the heart’s anterior surface

Answer 18

right ventricle

Question 19

what is observed from the heart’s posterior surface

Answer 19

left atrium

Question 20

what is observed from the heart’s diaphragmatic surface

Answer 20

R & L ventricles

Question 21

what is observed from the heart’s right pulmonary surface

Answer 21

right atrium

Question 22

what is observed from the heart’s left pulmonary surface

Answer 22

left ventricle

Question 23

right atrium

Answer 23

• houses the SA node (receives input from vagus nerve)
• crista terminalis: non-conductive ridge, divides pectinate muscles from smooth surface of RA
• fossa ovalis: fibrous sheet that covered the foramen ovale
• coronary sinus valve

Question 24

right ventricle

Answer 24

tricuspid valve, excess trabeculations relative to left ventricle, pulmonary semilunar valve

Question 25

left ventricle

Answer 25

mitral (bicuspid) valve, more muscular than right ventricle, delivers blood through aortic semilunar valve for systemic flow

Question 26

semilunar valves

Answer 26

the aortic valve has openings on its right and left leaflets for coronary arteries

Question 27

what are the heart sounds

Answer 27

• S1 is first sound, closing of a-v valves
• systole (ventricles contract)
• S2 is second sound, closing of semilunar vavles
• diastole (ventricles relax)

Question 28

conducting system of heart

Answer 28

1. SA node: along upper end of sulcus terminalis (near SVC); pacemaker; sympathetic and parasympathetic innervation
2. AV node: interatrial septum
3. Bundle of His
4. Bundle branches
5. Purkinje fibers

Question 29

function of the skeleton of the heart

Answer 29

• fibrous CT functions as attachment point for valves and muscles
• provides support and actsa as electrical insulator preventing conduction between atria and ventricles

Question 30

coronary arteries

Answer 30

• right and left artery arise from the (R &L aortic sinuses of aortic semilunar valve) and supply nutrients to the heart