Module 1A Unit 3: Anatomy of Heart and Mediastinum

Anterior associations of the heart

thymus, body of the sternum

posterior associations of the heart

right and left lungs, esophagus, aorta

inferior associations of the heart

central tendon of the diaphragm; inferior vena cava penetrates on right side @T8

base of heart

2nd costal interspace

right border of heart

just right to body of sternum

apex of heart

5th intercostal interspace @ midclavicular line; points anterior, inferior, left; primarily left ventricle

diaphragmatic border

crosses xiphisternal junction

right ventricle

anterior, occupying most of the sternocostal surface

left atrium

sitting at posterior aspect of heart

epicardium (visceral pericardium)

made up of mesothelium and adipose

myocardium

cardiac muscle (cardiac myocytes)

endocardium

made up of endothelium and subendothelial connective tissue, also covers valves

coronary sulcus

groove separating atria from ventricles; contains SA branch, R marginal branch

anterior and posterior interventricular sulci

divide R and L ventricles, meeting at a notch near apex

auricle

appendage of both left and right atria

cardiac fat

variable amount of fat occupying sulci; study

arteries

away from heart; oxygenated in systemic, deoxygenated in pulmonary

veins

towards heart; deoxygenated in systemic, oxygenated in pulmonary

coronary sinus

located in posterior atrioventricular groove, largest intrinsic vein of heart, drains into right atrium near IVC, guarded by thebesius valve

tricuspid valve

R AV valve, guarding the R atrioventiruclar ostium

3 cusps: anterior, posterior, septal (correspond to 3 papillary muscles)

valve of coronary sinus

small fold, barely prevents backflow into sinus

IVC valves

falciform fold; in fetus larger and directs blood from IVC-foramen ovale- L atrium

fossa ovalis

remnant of foramen ovale

chordae tendineae

fibrous cords from cusps of tricuspid/bicuspid valve to ends of papillary muscles

trabeculae carneae

ridge like bundles of muscles projecting into ventricle lumen, including SEPTOMARGINAL TRABECULA (Moderator band)

semilunar valve

aka pulmonary valve; 3 cusps— right, left, anterior

Left atrium

unremarkable, 4 pulmonary veins empty into L atrium

left auricle, interatrial septum

left ventricle

thick muscular pump to systemic circuit

interventricular septum

pars membranacae and pars muscularis

pars membranacae

thin dorsal membranous part of interventricular septum

pars muscularis

thick muscular ventral part of interventricular septum

bicuspid valve

aka L AV/mitral valve; 2 cusps— anterior and posterior

chordae tendineae w/ papillary muscles

prevent eversion of AV valves into atrium

aortic valve

semilunar valve; posterior to pulmonary semilunar valve; 3 valvules— left, right, posterior; prevents regurgitation into ventricle

obstruction of coronary arteries can cause

myocardial infarction or transient ischemic attack

left coronary artery

arises from sinus of left cusp of aortic valve; divides into anterior interventricular artery and circumflex branch

anterior interventricular artery

in sulcus of same name; supplies entire left ventricle and portions of right ventricle

weak anastomosis exists with the posterior interventricular branch of right coronary artery

left ventricle blood supply

anterior interventricular artery

left circumflex branch

major branch of left coronary artery, passes to posterior surface in coronary groove; terminates as posterior ventricular branch

right coronary artery

arises from right cusp of aortic valve; passes into coronary sulcus, giving rise to SA nodal branch, right marginal branch, then it becomes posterior interventricular branch, giving off AV node

anastomoses of heart vasculature

anterior interventricular artery and posterior interventricular artery

circumflex artery with right coronary artery

coronary sinus receives

great cardiac vein (ascends in anterior interventricular sulcus w/ artery to coronary sulcus, continues to left with circumflex artery to posterior surface)

middle cardiac vein (ascends in posterior interventricular sulcus w/ artery)

small cardiac vein: from front in the coronary sulcus with right coronary artery

coronary sinus drains into

right atrium

great cardiac vein

(ascends in anterior interventricular sulcus w/ artery to coronary sulcus, continues to left with circumflex artery to posterior surface)

middle cardiac vein

(ascends in posterior interventricular sulcus w/ artery)

small cardiac vein

from front in the coronary sulcus with right coronary artery

anterior cardiac veins

4 surface cardiac veins that drain directly into right atrium

SA node

pacemaker initiating contraction of heart muscle; located in right atrial wall between right auricle and superior vena cava at upper end of crista terminalis

crista terminalis

separating the smooth posterior (sinus venarum) from the rough, muscular anterior part (pectinate muscles of the right atrial appendage)

AV node location

near ostium of coronary sinus within interatrial septum

AV node function

creates lag so ventricles are full before contraction

Atrioventricular bundle function

bundle of his; pale colored purkinje fibers specialized for conduction of impulses to cardiac muscle fibers

helps create a milking action of ventricles (creating lag so ventricles full before contraction)

atrioventricular bundle location

extends from AV node into pars membranacae where it divides into the R and L crus of AV bundle

R crus crosses cavity via septomarginal trabecula/moderator band to base of anterior papillary muscle, ending in right ventricular wall

L crus passes deep to endocardium to left ventricular wall, close to valves

parasympathetic innervation of heart

right vagus— SA node

left vagus— AV node

sympathetic innervation to heart

T1-T4/5

right sympathetics— SA node

left sympathetics— AV node

right recurrent laryngeal nerve loops

inferior to right subclavian artery

left recurrent laryngeal nerve loops

ant, inf, posterior to arch of aorta

aortic arch

level of sternal angle (t4), 3 branches (BCT, LCCA ,LSCA), anterior then left of trachea

left vagus and left phrenic nerves cross on anterior surface

ascending aorta

enclosed within pericardial sac, origin of L and R coronary arteries in aortic sinus of aortic semilunar valve

semilunar valves

pulmonary and aortic

branches of descending thoracic aorta

pericardial, brochial, esophageal, mediastinal

posterior intercostal, subcostal, superior phrenic

descending aorta location

T4/5-T12; passes POSTERIOR to root of left lung

pulmonary trunk location

within pericardial sac, arising from conus arteriosus of right ventrical, ascending obliquely then passing anterior than left of ascending aorta near undersurface of aortic arch bifurcating into R and L pulmonary arteries

Right pulmonary artery

longer and larger than left, running posterior to ascending aorta and SCV, ANTERIOR to Right bronchus, dividing into 2 branches near right lung hilus (superior, inferior/middle)

left pulmonary artery

shorter, smaller

passes anterior to descending aorta and left bronchus

connects at origin to aortic arch via ligamentum arteriosum

to the left is the left recurrent laryngeal nerve, to the right is the superficial cardiac plexus

two branches: superior lobe, inferior lobe

pulmonary artery function

bring deoxygenated blood from heart to alveolar sacs for gaseous exchange (pulmonary respiration)

pulmonary trunk arises from

conus arteriosus (right ventricle)

ligamentum arteriosum

connects origin of left pulmonary artery to aortic arch

Brachiocephalic vein is formed by

internal jugular and subclavian veins

longer brachiocephalic vein

left brachiocephalic vein is 2.4”, right brachiocephalic vein is 1”

superior vena cava is formed by

junction of L+R brachiocephalic veins forms

tributaries to right brachiocephalic vein

same as left: R vertebral vein, R internal thoracic v, R inferior thyroid v

DIFFERENT: R 1st posterior intercostal (supreme) vein

tributaries to left brachiocephalic vein

same as right: L vertebral vein, L internal thoracic vein, L inferior thyroid vein

DIFFERENT: L highest (superior) intercostal vein

Azygos vein

UNPAIRED vein; begins opposite 1st or 2nd lumbar vertebrae form R ascending lumbar vein and a branch from IVC, passes over root of R lung (P-A) to SVC

Azygos vein relationship to lung

passes over root of lung P-A

Combine to from azygos vein

R ascending lumbar vein and IVC branch

tributaries to azygos vein

R highest (superior) intercostal vein, R posterior intercostal veins 5-11, R subcostal vein, hemiazygos v (T9), Accessory hemiazygos vein(T8 or joins hemiazygos), R bronchial veins

number of pulmonary veins

2/side=4 total

pulmonary vein function

returns oxygenated blood to left atrium

right pulmonary vein location

posterior to right atrium and SVC

left pulmonary vein location

anterior to descending thoracic aorta

superior mediastinum division

1st rib to level of sternal angle, T4/T5 disc

inferior mediastinum division

sternal angle to respiratory diaphragm; anterior, middle, posterior divisions

superior mediastinum contains

origins of sternohyoid + sternothyroid, thymus, proximal BCT, LCC, LSC arteries, upper 1.2 of SCV, L+R BCVs, thoracic duct posterior to aortic arch, trachea, esophagus, vagus nerves (L recurrent laryngeal n of vagus in tracheoesophageal groove), cardiac + phrenic nerves, lymph nodes, aortic arch

anterior mediastinum borders

S: lower border of superior mediastinum

I: diaphragm

A: sternal body

P: fibrous pericardium

anterior mediastinum contains

next to nothing, thymic remnants and fat

middle mediastinum borders

S; lower border of superior mediastinum

I: diaphragm

A: pericardial sac

P: pericardial sac

middle mediastinum contains

pericardial sac+ heart, lower ½ SVC, azygos termination, origin of pulmonary arteries, phrenic nerves (anterior to root of lung, then in external pericardial sac), pulmonary veins to left atrium, lymph nodes

phrenic nerves relation to lung

pass anterior to root of lung, then in external pericardial sac

thoracic duct drains

left internal jugular and subclavian veins

posterior mediastinum borders

s: lower border of superior mediastinum

I: diaphragm, until T12

A: pericardial sac

P: vertebral column

posterior mediastinum contains

, descending thoracic aorta + origins of posterior intercostal arteries, azygos v (right side), hemiazygos v (left side), R+L brongus, thoracic duct, thoracic splanchnic nerves, vagus nerves

most posterior structure on right side of posterior mediastinum

azygos vein

azygos vein relationship with bronchus

arches over right bronchus P-A

side of hemiazygos vein in posterior mediastinum

left posterior mediastinum

right vagus nerve in posterior mediastinum

near trachea, passes posterior to root of right lung, then runs on POSTERIOR surface of esophagus

Left vagus nerve in posterior mediastinum

passes over anterior L side of aortic arch, gives of L recurrent laryngeal nerve, then posterior to root of lung before running ANTERIOR surface of esophagus