Org Ana: Mediastinum and Heart Flashcards
what is the mediastinum
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
what are the boundaries of the mediastinum
sup - thoracic outlet and root of neck
inf - diaphragm
ant - sternum
post - thoracic vertebrae
lat - pleura
describe the superior mediastinum
above the sternal angle
boundaries:
ant - manubrium
post - T1-T4
what are the contents of superior mediastinum
thymus gland
large veins
large arteries
trachea
esophagus and thoracic duct
describe the inferior mediastinum
below the sternal angle and divides into anterior, middle and posterior
boundary:
ant - body of sternum
post - T5-T12
what are the contents of inferior mediastinum
ant: thymus
middle: heart with pericardium and phrenic nerve on sides
post: esophagus and thoracic duct, descending aorta and sympathetic trunks
what is the pericardium
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
describe serous pericardium
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
what is the pericardial cavity
space between parietal and visceral that contains 50 ml of pericardial fluid
describe fibrous epicardium
strong fibrous outer layer attached to central tendon
fuses w outer coats of great vessels
attaches to sternum via sternopericardial ligament
what is pericarditis
inflammation of pericardium bc of excessive fluid that causes compression of the atrium interfering with filling during diastole
what is cardiac tamponade
can occur secondary to stab or gsw when chambers are penetrated
compression of heart
describe the heart
muscular organ
pyramidal
found in mediastinum
connected at the base to great vessels
describe the orientation of the heart
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
what is the sternocostal surface of the heart
anterior surface formed by RA and RV separated by AV groove or coronary sulcus
anterior interventricular groove separates RV and LV
what is the diaphragmatic surface of the heart
inferior surface formed by RV and LV separated by posterior interventricular groove
inferior surface of atrium where IVC opens forms part of this
what is the base surface of the heart
posterior surface formed by LA where 4 pulmonary veins open
opposite apex
what are the borders of the heart
right - RA
left - left auricle and LV
inferior - RV and portion of RA
apex - LV
discuss the layers of the heart from superficial to deep
epicardium - visceral pleura
myocardium - cardiac muscle; contracts
endocardium - endothelium on CT; lines heart and creates valves
explain the fibrous cardiac skeleton
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
compare atria and ventricles
atria wall is thin divided by interatrial septum
ventricles have thick walls divided by interventricular septum
describe the right atrium
primary pump
has main cavity and auricle
recieves O2 poor blood
ventral wall made of rough pectinate muscle
has fossa ovalis on interatrial septum
what is sulcus terminalis and crista terminalis
sulcus: vertical groove on outside surface at the junction betw RA and auricle
crista: same but on inside surface
what are the openings of the RA
SVC and IVC
coronary sinus
RV orifice - tricuspid valve
describe the RV
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
what are the 3 types of trabeculae carnae of the RV
papillary muscle
moderator band
prominent ridges
muscular bundles that form bridges
describe the papillary muscles
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
what is the moderator band
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
what are the valves found in the right side of the heart
R AV valve - betw R atrium and R ventricle
pulmonary valve - betw R ventricle and pulmonary vein
- closed during diastole or ventricular filling
describe the LA
consists of main cavity and auricle
upper wall - smooth
lower wall - pectinate
recieves O2 rich blood from pulmonary veins
describe the LV
has the thickest wall and no moderator bands
L AV valve - bicuspid
aortic valve - contains aortic sinus
what is the aortic sinus
ant aortic sinus - right coronary a.
left posterior sinus - left coronary a.
what is the extrinsic nerve supply of the heart
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
what is the intrinsic nerve supply of the heart
via conducting system of heart
where is the SA node located
wall of RA betw crista terminalis and SVC
where is the AV node located
right lower atrial septum
where is the AV bundle of his located
at the ventricular septum
discuss the conducting system sequence
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
what has the highest conduction velocity
subendocardial branches or pukinje fibers
4-5 m/s
what does the right coronary artery supply to
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%
describe the right coronary artery
descend vertically from ant aortic sinus
what are the branches of the right coronary artery
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
describe the left coronary artery
larger; supplies LA, LV and ventricular septum
from left aortic sinus
what does the left coronary artery supply
LA
LV
RV
ventricular septum - 2/3
SA node - 40%
AV and bundle branches
what are the branches of the left coronary artery
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
explain the venous drainage of the heart
most blood drains to RA via coronary sinus
great cardiac vein - left coronary
middle and small cardiac vein - right coronary artery
what is myocardial infarction
when coronary flow is reduced or stopped = cardiac tissue undergoes necrosis
what is angina pectoris
cardiac pain on exertion and relieved by rest or nitroglycerin (vasodilates)
