Mediastinum and Heart: Content and Organization Flashcards
Boundaries
Posterior: Vertebral column Anterior sternum and cartilage Lateral: pleura inferior: diaphragm Superior: thoracic inlet
Mediastinum: Superior
Great vessels of the heart, thoracic duct (left), (cardiac, pulmonary, esophageal) autonomic nerve plexuses, recurrent laryngeal nerves, esophagus, thymus, azygos system, parts of trachea
mediastinum: Inferior, anterior
Anterior: lymph tissue, fat
Mediastinum: Inferior, posterior
Posterior: pulmonary arteries and veins, thoracic aorta, azygos veins, sympathetic trunk + thoracic splanchnic nerves, thoracic duct
Mediastinum: Inferior, middle
the heart and its pericardial tissues
Vagus and laryngeal recurrent nerves: how and where do they go
RIGHT vagus anterior to brachiocephalic trunk but posterior to R. brachiocephalic vein/L. brachiocephalic vein
LEFT vagus runs anterior to arch of the aorta and posteriorly to the left subclavian vein
LEFT recurrent laryngeal nerve runs posteriorly to arch of the aorta, loops under it and behind the ligamentum arteriosum to connect with the vagus nerve
Considering the midline of the body, where is the heart located?
left of the midline, posterior to sternum, middle of mediastinum
How is the heart positioned in the middle of the mediastinum?
Rotated such that right side (Right atrium and ventricle) is located more anteriorly
left side is located more posteriorly
posteriosuperior surface of the heart =
formed primarily by left atrium, called the base
What vessels enter the left boarder of the base of the heart?
pulmonary veins
the apex points
slightly anteroinferiorly toward left side of the body
posterior spatial relationships between vessels
- pulmonary veins to pulmonary arteries
- pulmonary arteries to aorta
- aorta to brachiocephalic vein
from anterior to posterior to inferior (front of the heart to the back of the heart to the midline of the heart)
- bilateral pairs of pulmonary veins are inferior to pulmonary arteries
- pulmonary arteries are inferior, posterior to arch of the aorta, diverge into L (one vessel) and R (two vessels) on either side
Pericardium
fibrous, serous sac
held in place within the mediastinum by connective tissue that supports the great vessels external walls superior to the heart and the diaphragm
outer portion is touch, dense connective tissue layer called the fibrous pericardium
Fibrous pericardium
dense connective tissue layer called the fibrous pericardium
attached to both the sternum and diaphragm
Functions of the pericardium
restricts heart movement so it doesn’t bounce and move in the thoracic cavity
prevents heart from overfilling with blood
Inner pericardium
serous pericardium
Layers of the pericardium
Epicardium: visceral layer of serous pericardium
myocardium
Endocardium
The older we get, more fat deposits in what part of the heart?
the epicardium
the thickest muscle layer in the heart is the
myocardium
the muscle surface in the heart is the
endocardium
the endocardium covers the
internal surface of the heart and valves, as well as the external surface of the valves
between the myocardium and the endocardium is a layer called
the subendocardial layer, composed of areolar connective tissue
External anatomy
artria separated from ventricles externally by the coronary sulcus, extends around circumference of the heart
anterior/posterior interventricular sulcus are located between left/right ventricles
these sulci extend inferiorly to the apex of the heart
Functions of the Fibrous skeleton
separates ventricles from atria
anchors heart valves by forming supportive rings of attachment
provides electrical insulation between atria and ventricles
insulations ensures muscle impulses are not separated at random, preventing heart chambers from beating at the same time
provides rigid framework for attachment of cardiac muscle tissue
Right atrium (from memory)
receives blood from IVC/SVC, coronary sinus, has pectinate muscle and separated from Left Atria via interatrial septum
Right Ventricle (from memory)
interventricular spetum separates R/L ventricles
has three papillary muscles which anchor the chordae tendineae
Left atrium
posterior wall contains four openings for pulmonary veins
anterior wall contains small amount of pectinate muscle, and an auricle
Left ventricle
largest of the four chambers
wall is 3 times thicker than Right ventricle because it is supplying blood to the systemic circuit
trabeculae carneae in the left are more prominent
TWO papillary muscles attach to chordae tendineae
Pulmonary trunk
superior end narrows into smooth walled, conical region called conus arteriosus
marks end of right ventricle and entrance of the pulmonary trunk
conduction system of heart
possesses autorhythmicity
contractile muscles in the myocardium
Sinoatrial node and atrioventricular node
Sinoatrial node is located in the posterior, superior wall of the right atrium below the superior vena cava
the atrioventricular node is located between the floor of the AV valve and the coronary sinus
path of conduction
SA node –> AV node –> bundle of His —> purkinje fibers –> spreads from apex throughout ventricular myocardium
Innervation of the heart
symp/parasym via cardiac/coronary plexus
sym INCREASES rate and force of heart contractions
parasym decreases rate, but HAS NO EFFECT ON FORCE OF CONTRACTION, except in special circumstances
Coronary circulation
L/R coronary arteries travel in coronary sulcus (atrioventricular groove) of heart to supply heart wall
Right coronary artery branches into marginal artery, supplies right border of the heart
posterio
marginal artery
branches from the right coronary artery
supplies the right border of the heart
Posterior interventricular artery
branches from the right coronary artery
supplies both left and right ventricles
Left coronary artery branches into
anterior interventricular artery
circumflex artery
LAD
left anterior descending artery, branches from left coronary artery
supplies anterior surface of both ventricles and interventricular septum
circumflex artery
supplies left atrium and ventricle
cardiomyopathies (two kinds)
dilated cardiomyopathy
left ventricle weakened, struggles to pump enough blood to meet the body’s needs
hypertrophic myopathy
left ventricle does not fully relax between heartbeats