Arterial supply anatomy INCOMPLETE ADD THE LITERAL ARTERIES

• mediastinum

• The ‘space’ located between the lungs, bounded anteriorly by the sternum and posteriorly by the vertebral column

• divided into superior and inferior

go to gray’s anatomy for students and search “subclavian artery” for good pictures

• superior mediastinum

• boundaries formed by superior thoracic inlet/aperture to transthoracic plane

• essentially everything in the thorax above the manubriosternal joint (T4/T5 vertebral level)

• contains great vessels of the heart

superior thoracic inlet/aperture

• forms upper border of superior mediastinum

• upper opening of the thoracic cavity through which major vessels emerge:

  • Aortic arch and its branches

  • Superior vena cava (SVC)

  • Brachiocephalic veins

  • Trachea and esophagus

transverse thoracic plane

• forms lower border of superior mediastinum and upper border of inferior mediastinum

• line from the sternal angle anteriorly → IV disk between T4 and T5 posteriorly

• inferior mediastinum

• Extends from transverse thoracic plane to diaphragm

• divided into anterior, middle and posterior

• anterior mediastinum

• Prevascular compartment

• Potential space with thymus, lymph nodes, fat and nerves

• middle mediastinum

• Visceral compartment

• Contains the heart, pericardium and origins of great vessels

• posterior mediastinum

• Posterior to pericardial sac and anterior to mid/low thoracic vertebrae

• Contains esophagus, descending aorta and thoracic duct

aortic dissection (definition, pain, consequences)

• tear in the tunica intima (innermost layer) creating a false lumen/second passage for blood to flow through

• centralised, sharp chest pain radiating to their back

• Consequences:

  • organ ischemia/infarction:

    If blood flow in the false lumen diverts flow away from branch vessels (e.g., renal arteries → kidney ischemia)

  • Cardiac tamponade:

    If the dissection is in the ascending aorta or aortic arch (inside the pericardial sac)

    → blood leaks into the pericardial cavity, accumulating around and compressing the heart

    → heart can't pump properly

    → death

  • Hemothorax:

    If the aorta ruptures into the thoracic cavity

    → rapid internal bleeding

    → sudden death

aortic dissection predisposing factors

• Chronic hypertension (2/3rds all cases)

  • arteries in tunica adventitia become artheroslcerotic

    → tunica media + intima integrity at risk

• Connective tissue disease (e.g. Marfan syn)

ligamentum arteriosum

• remnant of the fetal ductus arteriosus, a vessel connecting the pulmonary trunk to the aorta in the developing fetus

• thickening of tunica media, distal to ligamentum arteriosum leads to aortic coarction

pericardium

• A fluid-filled membranous sac that encloses the heart and roots of the great vessels

• protects the heart & provides lubrication to reduce friction between heart and surroundings

• three layers:

  • fibrous pericardium

  • Serous pericardium

  • Pericardial cavity

• fibrous pericardium

• fibro-serous sac continuous with the central tendon of diaphragm

• Encloses heart & roots of great vessels

• pericardial cavity

• space between parietal & visceral layers of serous pericardium

• Contains thin film of fluid

serous pericardium

visceral (epicardium) and parietal

acute pericarditis

• inflammation of layers of the pericardium

• Sharp pain localised to middle or left thorax - radiates to neck or shoulders

cardiac tamponade

pericardial cavity becomes overly filled with fluid (pericardial fluid or blood)

pretend the box is two lines up

endocardium

epicardium/visceral serous

myocardium

esophagus

(superior mediastinum)

left brachiocephalic vein

(superior mediastinum)

trachea

(superior mediastinum)

right brachiocephalic vein

(superior mediastinum)

anterior cusp (tricuspid valve)

anterior papillary muscle

• pulls on chordae tendineae when contracted to keep tricuspid valve closed

anterior semilunar cusp (pulmonary valve)

arch of aorta

arches predominantly in the sagittal plane (front to back)

(superior mediastinum)

chordae tendineae

• made from collagen

conus arteriosus

• funneling structure for pulmonary valve

left auricle

left semilunar cusp (pulmonary valve)

posterior cusp (tricuspid valve)

posterior papillary muscle

• pulls on chordae tendineae when contracted to keep tricuspid valve closed

pulmonary trunk

right atrium

right auricle

right semilunar cusp (pulmonary valve)

septal cusp (tricuspid valve)

septal papillary muscle

septomarginal trabecula/moderator band

• made of muscular tissue, connected to wall of ventricle

superior vena cava

(superior mediastinum)

trabeculae carneae

• rugous tissue

great cardiac vein

left anterior descending artery (LAD)

left coronary artery

supplies: left atrium, most of left ventricle, part of right ventricle, anterior two-thirds of IVS (interventricular septum), including the AV bundle

branch from the base of the aorta

middle cardiac vein

posterior descending artery (PDA)

• Right Dominance (70-85% of people):

  • (PDA) originates from the right coronary artery (RCA).

  • The right coronary artery supplies both the PDA and the posterior part of the heart.

• Left Dominance (10-15% of people):

  • The PDA originates from the left circumflex artery (LCx), a branch of the left coronary artery (LCA).

  • The left coronary artery thus supplies most of the heart, including the posterior portion.

• Co-Dominance (5-10% of people):

  • The PDA receives contributions from both the right coronary artery and the left circumflex artery.

  • Both arteries share responsibility for the blood supply to the posterior part of the heart.

right coronary artery (RCA)

supplies:

• diaphragmatic surface of the heart

• the right atrium, most of right ventricle, diaphragmatic part of left ventricle, and posterior third of interventricular septum

small cardiac vein

anterior papillary muscle

arch of aorta

chordae tendineae

coronary sinus
largest vein of the heart

left atrium

mitral valve anterior cusp

mitral valve posterior cusp

posterior papillary muscle

pulmonary arteries

pulmonary veins

trabeculae carneae

ascending aorta

brachiocephalic trunk

first branch of aortic arch → carries oxygenated blood to the upper right side of your body

descending aorta

inferior vena cava

left common carotid artery

oxygenated blood → brain, face, and neck

(left originates from aortic arch)

(superior mediastinum)

left pulmonary artery

left pulmonary artery

left subclavian artery

oxygenated blood → head, neck, arms

pulmonary trunk

right common carotid artery

oxygenated blood → brain, face, and neck

(right originates from brachiocephalic trunk)

(superior mediastinum)

right pulmonary artery

right pulmonary veins

right subclavian artery

oxygenated blood → head, neck, arms

superior vena cava

(superior mediastinum)

trachea

Atrioventricular valves

• between atrium and ventricle

• Tricuspid (Right Atrium → Ventricle) (3 cusps)

• Mitral (Left Atrium → Ventricle) (2 cusps)

• After a ventricular contraction, pressure in the ventricles exceeds the pressure in the atria, so the AV valves shut

semilunar valves

• between ventricles and great vessels

• Pulmonary (R.Ventricle → Pulmonary trunk)

• Aortic (L.Ventricle → Ascending Aorta)

• The semilunar valves are closed because the ventricular pressure is lower than the aorta and the pulmonary artery

opening of coronary sinus

crista terminalis

fossa ovalis

musculi pecinati

right auricle

right ventricle

valve of coronary sinus

auscultation site 1

aortic valve (APTM)

R. of sternum at 2nd intercostal space

auscultation site 2

pulmonary valve (APTM)

L. of sternum at 2nd intercostal space

auscultation site 3

tricuspid valve (APETM)

L. of sternum at 4th intercostal space

auscultation site 4

mitral valve (APETM)

L. of sternum at 5th intercostal space (midclavicular line)

auscultation site 5

Erb’s point

L. of sternum at 3rd intercostal space

transverse pericardial sinus

(impressions in the pericardial sac formed between the points where great vessels enter it)

Located posterior to the roots of the ascending aorta and pulmonary trunk

Clinical significance: can be used to identify the arteries of the heart during coronary artery bypass grafting

oblique pericardial sinus

(impressions in the pericardial sac formed between the points where great vessels enter it)

Located posterior to the left atrium; between R and L pulmonary veins

No clinical significance.

neurovascular bundle

structure consisting of an artery, vein and nerve bound together by connective tissue

artery types of branching

• Terminal branch

  • artery ends by dividing/bifurcating into multiple branches

• Collateral branch

  • side branch comes off the main artery

• Continuation

  • artery changes name as it passes a landmark (functionally the same vessel)

• Anastomosis

  • artery connects with another artery, forming arches/circles (backup blood supply if there is an occlusion)

aortic coarctation

narrowing of the aorta that occurs near the ligamentum arteriosum just distal to the origin of the left subclavian artery

• Infantile (pre-ductal): narrowing before the ductus arteriosus. Presents in infancy with heart failure

  • radial-radial delay

• Adult (post-ductal): narrowing after the ductus. Collateral circulation develops (via intercostal and internal mammary arteries)

  • radial-femoral delay