Org Ana: Mediastinum and Heart

Question 1

what is the mediastinum

Answer 1

tough and thick movable partition betw sternum and pleural cavities and the vertebrae

divides into superior and inferior through the plane passing sternal angle anteriorly and lower border of T4 body

Question 2

what are the boundaries of the mediastinum

Answer 2

sup - thoracic outlet and root of neck
inf - diaphragm
ant - sternum
post - thoracic vertebrae
lat - pleura

Question 3

describe the superior mediastinum

Answer 3

above the sternal angle

boundaries:
ant - manubrium
post - T1-T4

Question 4

what are the contents of superior mediastinum

Answer 4

thymus gland
large veins
large arteries
trachea
esophagus and thoracic duct

Question 5

describe the inferior mediastinum

Answer 5

below the sternal angle and divides into anterior, middle and posterior

boundary:
ant - body of sternum
post - T5-T12

Question 6

what are the contents of inferior mediastinum

Answer 6

ant: thymus

middle: heart with pericardium and phrenic nerve on sides

post: esophagus and thoracic duct, descending aorta and sympathetic trunks

Question 7

what is the pericardium

Answer 7

fibroserous sac enclosing heart and roots of great vessels

lubricated container and prevent excessive movement

boundaries:
ant - body of sternum
lat - 2nd to 6th CC
post - T5-T8

Question 8

describe serous pericardium

Answer 8

lines fibrous pericardium and coats heart

parietal - inner of fibrous pericardium and reflex around roots of great vessels

visceral - applied to epicardium

parietal continues to become visceral

Question 9

what is the pericardial cavity

Answer 9

space between parietal and visceral that contains 50 ml of pericardial fluid

Question 10

describe fibrous epicardium

Answer 10

strong fibrous outer layer attached to central tendon

fuses w outer coats of great vessels

attaches to sternum via sternopericardial ligament

Question 11

what is pericarditis

Answer 11

inflammation of pericardium bc of excessive fluid that causes compression of the atrium interfering with filling during diastole

Question 12

what is cardiac tamponade

Answer 12

can occur secondary to stab or gsw when chambers are penetrated

compression of heart

Question 13

describe the heart

Answer 13

muscular organ

pyramidal

found in mediastinum

connected at the base to great vessels

Question 14

describe the orientation of the heart

Answer 14

oblique w apex pointing down, forward and left

2/3 midline on left side

LV from apex at 5th ICS 3.5 in away from midline

Question 15

what is the sternocostal surface of the heart

Answer 15

anterior surface formed by RA and RV separated by AV groove or coronary sulcus

anterior interventricular groove separates RV and LV

Question 16

what is the diaphragmatic surface of the heart

Answer 16

inferior surface formed by RV and LV separated by posterior interventricular groove

inferior surface of atrium where IVC opens forms part of this

Question 17

what is the base surface of the heart

Answer 17

posterior surface formed by LA where 4 pulmonary veins open

opposite apex

Question 18

what are the borders of the heart

Answer 18

right - RA
left - left auricle and LV
inferior - RV and portion of RA
apex - LV

Question 19

discuss the layers of the heart from superficial to deep

Answer 19

epicardium - visceral pleura

myocardium - cardiac muscle; contracts

endocardium - endothelium on CT; lines heart and creates valves

Question 20

explain the fibrous cardiac skeleton

Answer 20

made of four interconnected fibrous rings that surround AV, pulmonary and aortic valve orifices

continous w lower part of atrial septum and upper part of ventricular septum

attachment for muscle fibers and support the bases of valve cusps keeping valves patent

electrical insulation betw atria and ventricles

Question 21

compare atria and ventricles

Answer 21

atria wall is thin divided by interatrial septum

ventricles have thick walls divided by interventricular septum

Question 22

describe the right atrium

Answer 22

primary pump

has main cavity and auricle

recieves O2 poor blood

ventral wall made of rough pectinate muscle

has fossa ovalis on interatrial septum

Question 23

what is sulcus terminalis and crista terminalis

Answer 23

sulcus: vertical groove on outside surface at the junction betw RA and auricle

crista: same but on inside surface

Question 24

what are the openings of the RA

Answer 24

SVC and IVC
coronary sinus
RV orifice - tricuspid valve

Question 25

describe the RV

Answer 25

communicates with RA; recieves O2 poor blood through tricuspid valve and pumps to the pulmonary vein through pulmonary valve funnel shaped towards pulmonary orifice - infundibulum

Question 26

what are the 3 types of trabeculae carnae of the RV

Answer 26

papillary muscle moderator band prominent ridges muscular bundles that form bridges

Question 27

describe the papillary muscles

Answer 27

cone shaped muscles where chordae tendinae are attached to connecting to the cusp of tricuspid valve ant - largest and most constant post - 1-3 structures from ventricular wall septal - inconsistent; from septal wall

Question 28

what is the moderator band

Answer 28

muscular band forming a bridge connecting ant papillary to interventricular septum attaches at end of ventricular wall and free in middle resists over distention of AV wall also carries part of cardiac conduction system - R AV bundle branch

Question 29

what are the valves found in the right side of the heart

Answer 29

R AV valve - betw R atrium and R ventricle pulmonary valve - betw R ventricle and pulmonary vein - closed during diastole or ventricular filling

Question 30

describe the LA

Answer 30

consists of main cavity and auricle upper wall - smooth lower wall - pectinate recieves O2 rich blood from pulmonary veins

Question 31

describe the LV

Answer 31

has the thickest wall and no moderator bands L AV valve - bicuspid aortic valve - contains aortic sinus

Question 32

what is the aortic sinus

Answer 32

ant aortic sinus - right coronary a. left posterior sinus - left coronary a.

Question 33

what is the extrinsic nerve supply of the heart

Answer 33

sympathetic - upper thoracic spinal segments - cardiac acceleration and inc force of contraction - dilation of coronary arteries parasympathetic - vagus nerve - reduction in rate and force of contraction - constriciton of the coronary arteries

Question 34

what is the intrinsic nerve supply of the heart

Answer 34

via conducting system of heart

Question 35

where is the SA node located

Answer 35

wall of RA betw crista terminalis and SVC

Question 36

where is the AV node located

Answer 36

right lower atrial septum

Question 37

where is the AV bundle of his located

Answer 37

at the ventricular septum

Question 38

discuss the conducting system sequence

Answer 38

SA node - AV node - AV bundle of his - R and bundle branches R bundle branch - moderator band - purkinje fibers L bundle branch - ant and post - purkinje plexus

Question 39

what has the highest conduction velocity

Answer 39

subendocardial branches or pukinje fibers 4-5 m/s

Question 40

what does the right coronary artery supply to

Answer 40

aortic sinus betw pulmonary trunk and R auricle RA and most of RV LV - diaphragmatic surface posterior third of ventricular septum SA node - 60% AV node - 80%

Question 41

describe the right coronary artery

Answer 41

descend vertically from ant aortic sinus

Question 42

what are the branches of the right coronary artery

Answer 42

right conus - RV ant ventricular branches - ant RV and apex and costal surface; largest post ventricular branches - RV and AV node post interventricular - RV and LV, AV node atrial - RA and SA node

Question 43

describe the left coronary artery

Answer 43

larger; supplies LA, LV and ventricular septum from left aortic sinus

Question 44

what does the left coronary artery supply

Answer 44

LA LV RV ventricular septum - 2/3 SA node - 40% AV and bundle branches

Question 45

what are the branches of the left coronary artery

Answer 45

ant ventricular - RV and LV - left diagonal - left conus circumflex - from ant ventricular - left marginal - LV to apex - ant and post ventricular - LV - atrial - LA

Question 46

explain the venous drainage of the heart

Answer 46

most blood drains to RA via coronary sinus great cardiac vein - left coronary middle and small cardiac vein - right coronary artery

Question 47

what is myocardial infarction

Answer 47

when coronary flow is reduced or stopped = cardiac tissue undergoes necrosis

Question 48

what is angina pectoris

Answer 48

cardiac pain on exertion and relieved by rest or nitroglycerin (vasodilates)