middle medisatinum Flashcards
what are the boundaries of the middle mediastinum? 5
- anterior= anterior pericardium
- posterior= posterior pericardium
- lateral= mediastinal pleura
- inferior= diaphragm
- superior= T4/5
what are the contents of the middle mediastinum? 5
- heart and pericardium
- ascending aorta
- pulmonary trunk and arteries
- pulmonary veins
- nerves
what do auricles looks like?
a dog on the outside of the heart, and add more volume for blood filling
what are the pulmonary veins?
- two veins from each side, inferior and superior
what are the two regions of the right atrium?
- sinus venarum (smooth walled)
- pectinate muscle
what types of muscle are in the right atrium?
- smooth muscle allowing the flow of blood
-pectinate muscle of the atrium- good to push blood during a contraction
separated by the crista terminalis
how does deoxygenated blood flow into the right atrium?
- superior vena cava
- inferior vena cava
- coronary sinus
describe the muscle in the left atrium?
predominantly smooth walled
what are the structures inside the left and right ventricles? 4
- chordae tendineae
- trabeculae carneae
- papillary muscle
- right ventricle= moderator band
name the cusps of the atrioventricular valves?
- bicuspid= anterior and posterior
- tricuspid= anterior, posterior and septal
what are the cusps of the pulmonary and aortic valves?
- pulmonary= left, right, anterior
- aortic= left, right, posterior
where do the coronary arteries come from?
- right coronary artery from the right cusp
- left coronary artery from the left cusp of the aortic valve
what is the pericardium? 4
- 3 layered sac which the heart is suspended on
- attached to the great vessels superiorly and diaphragm inferiorly
- influenced by the movement of the great vessels, sternum and diaphragm
- phrenic nerve travels over the pericardium
what are the functions of the pericardium?
- protects the heart from overfilling (cardiac distention)
- retains heart in position (pericardial-sternal ligaments)
what are the layers of pericardium? 3
- serous pericardium (internal) (parietal layer, visceral layer/ epicardium)
- fibrous pericardium (external)
- pericardial cavity is located between the parietal and visceral pericardium, contains some serous fluid to allow for uninhibited movement
describe the pericardial sinuses? 3
- a sac or cavity where the parietal and visceral layers of the serous pericardium meet
- transverse sinus- located between the outflow vessels of the heart (AA+PT) and the inflow vessels (SVC+PV) (can be used in surgery to clamp the outflow of blood from the heart)
- oblique sinus- located between the pulmonary veins
describe the coronary circulation? 3
- the heart requires its own blood supply, this is provided by the coronary arteries and veins
- coronary vessels are located in the atrioventricular grooves
- two main coronary arteries arise from the ascending aorta- left and right
what are the right coronary arteries that we need to know? 4
- right coronary artery
- sinus-atrial nodal branch or right coronary artery
- right marginal branch of right coronary artery
- posterior interventricular branch of right coronary artery
what are the left coronary arteries that we need to know? 5
- left coronary artery
- circumflex branch of left coronary artery
- left marginal branch of circumflex branch
- anterior interventricular branch of the left coronary artery
- diagonal branch or anterior interventricular branch
what are anastomoses? 3
- functional (potential) anastomoses exist between the coronary artery branches
- end branches of the anterior interventricular artery with the posterior interventricular artery
- however these do not maintain substantial collateral circulation if major branch is occluded suddenly
explain coronary arteries dominance and variation? 6
- dominance is defined by the artery which gives rise to the posterior IV artery
- 67% of individuals are RCA dominant
- 15% are LCA dominant, where the posterior IV artery branches from the circumflex artery
- variation in the coronary circulation is common
- 4% of individuals have an accessory CA
- 40% of the population- the SA nodal branches come off the circumflex
what are the cardiac veins? 5
- great cardiac veins
- posterior cardiac vein
- coronary sinus (drains into the right atrium)
- small cardiac vein
- middle cardiac vein
what is the location of the sinoatrial node?
what does it initiate?
- close to the crista terminalis at the junction between the SVC and right atrium
- contraction impulses spread through the atrial wall to the AV node
what is the location of the atrioventricular node?
what does it initiate?
- interatrial septum close to coronary sinus opening
- AV node continues into the AV bundle (of His) and divides in the interventricular septum to travel to left and right ventricles to conduct the impulse to the left and right purkinjie fibres
