heart, SA and chambers Flashcards
what is the angle of louis in relation to the mediastinum?
- formed by the junction of the manubrium (upper part of sternum) and the body of the sternum (lower part)
- located typically at the level of the 2nd rib and the IV disc between T4 and T5
What does the anterior mediastinum contain?
-contains no major structures
-thymus gland - seen in children in surgery but seen as more fibrotic tissue in adults
-fat
-lymphatic vessels and lymph nodes
what are the subdivisions of the mediastinum?
- superior mediastinum
- inferior mediastinum - which is divided into 3 further parts - anterior, middle and posterior
what does the middle mediastinum contain?
- largest subdivision of the inferior mediastinum
-contains the heart and its pericardium
-contains the tracheal bifurcation into the left and right bronchi
-associated with the origins of the ascending aorta, pulmonary trunk, superior vena cava
what is the pericardium?
a double walled membrane that surrounds the heart
what are the roles / functions of the pericardium?
-protection
-prevention of overstretching
-lubrication - the pericardial fluid in the pericardial cavity reduces friction between the layers allowing heart to move smoothly during contractions
what are the 2 layers of the pericardium?
- fibrous layer - tough fibrous sac that provides protection to the heart and anchors it to the chest cavity
- serous pericaridum - inner layer, more delicate and thin - produces a lubricating liquid called pericardial fluid
what 2 layers is the serous pericardium divided into?
- parietal layer -llines the fibrous pericardium
-visceral layer (epicardium) - close to the surface of the heart
what is the fibrous pericardium attached to?
- great vessels
-central tendon of diaphragm
-sternum - sternopericardial ligament
-parietal layer of serous pericardium
what is the pericardial cavity?
space within the pericardium between the parietal and visceral layer of the serous pericardium
what does the pericardial cavity contain and why?
-pericardial fluid
-this helps to facilitate gliding mats - beating of the heart
what are the pericardial sinuses?
-spaces within the pericardial cavity - there are 2 main ones
- these are the transverse pericardial sinus and the oblique pericardial sinus
Describe the great vessels of the heart
-major blood vessels that are connected to the heart
1. aorta - originates from LV, largest artery in body
2. pulmonary artery- originates from right ventricle, carries de ox blood from heart to lungs
3. superior vena cava - large vein that carries deoxygenated blood from upper part of body (head, neck,arms ) to right atrium of heart
4. inferior vena cava- large vein that brings deoxygenated blood from lower part of body (trunk, abdomen and legs) to right atrium of heart
5. pulmonary veins - 4 in total , 2 from each long, carry ox blood from lungs to left atrium of heart
what are the pericardial vessels and nerves?
- vessels and nerves that are associated with the pericardium - they contribute to the vascular supply and innervation of the pericardium
- eg pericardiophrenic arteries arising from the internal thoracic arteries, phrenic nerves (sensory info to pericardium)
What does the phrenic nerve innervate?
-mixed nerve
-motor innervation to the diaphragm
-sensory info to pericardium
what are the 4 chambers of the heart?
-right atrium
-right ventricle
-left atrium
-left ventricle
Describe the right atrium
- right atrium receives does blood from the superior and inferior vena cavae
- it forms the right border of the heart
-there is a right auricle (muscular pouch) attached to it
-inferior can be divided into 2 parts which are separated by the muscular ridge called the crista terminals
what are the 2 divisions of the right atrium?
-sinus venarum - located posterior to the crista terminals - this part receives blood from both vena cave
-atrium proper - located anterior to the crista terminals and includes the right auricle- rough muscular walls
what is the function of the auricles attached to the atrium?
they act to increase the capacity of the atrium
what is the interatrial septum?
-solid muscular wall that separates the right and left atria
what is the septal wall in the right atrium marked by?
a small oval shaped depression called the fossa ovalis - the remnant of the foramen vale in the feral heart
describe the left atrium
-LA receives ox blood from the 4 pulmonary veins and pumps it through to the LV
-LA forms the base of the heart and also contains a left auricle
Describe the right ventricle
- receives does blood from the RA and pumps it into the pulmonary artery
-divided into an inflow and outflow portion - which is separated by a muscular ridge called the supraventricular crest
what are the series of irregular muscular elevations in the RV called?
trabeculae carnae
what are the papillary muscles?
-small muscles located within the ventricles of the heart
- important for the functioning of the av valves - mitral and tricuspid valves
-they are connected to the chord tendinae
what happens when the papillary muscles contract?
- they pull on the chord tendineae
what is the inter ventricular septum?
a septum that separates the 2 ventricles
what is the function of the papillary muscles?
-They attach to the cusps of the atrioventricular valves via the chordae tendineae and contract to prevent inversion or prolapse of these valves during ventricular contraction
describe the LV
-receives ox blood from the LA and pumps it into the aorta
-lV forms the apex of the heart and the left and diaphragmatic borders
-also divided into an inflow and outflow portion like the RV
how many papillary muscles are in there in the RV and LV & what do they attach to?
-RV - 3 papillary muscles - attach onto the cusps of the tricuspid valve
-LV - 2 papillary muscles - attach onto the cusps of the mitral valve
what is the apex beat?
the lowest and most lateral point on the chest wall where you can feel the heart beating
-5th left intercostal space
what is an atrial septal defect?
hole in the wall between the 2 atria
congenital - born with it
what is a ventricular septal defect
-hole in the wall between the 2 ventricles
- congenital
what are the branches of the aortic arch?
-brachiocephalic trunk
-left common carotid artery
-left subclavian artery
what is the aortic arch?
a curved or arched segment of the aorta
what does the brachiocephalic trunk divide into?
- the right common carotid artery
-right subclavian artery
what are the valves in the heart?
- atrioventricular valves - tricuspid valve and biscupid valve
-semilunar valves - pulmonary and aortic valves (located between the ventricles and their corresponding artery)
describe the tricuspid valve
-located between the RA and RV
-3 cusps - anterior , septal and posterior
-each base of the cusp is anchored to a fibrous ring
describe the mitral valve / bicuspid valve
-between the LA and LV
-2 cusps - anterior and posterior
-base of each cusp is anchored to a fibrous ring
describe the pulmonary valve
-located between the RV and the pulmonary trunk
-3 cusps - left, right and anterior (named by position in the foetus)
describe the aortic valve
-located between the LV and ascending aorta
- 3 cusps - right, left and posterior
-anterior cusp is right cusp, posterior cusp is right posterior cusp and left cusp is left posterior cusp
what is aortic stenosis & list causes ?
narrowing of the aortic valve - which restricts the flow of blood leaving the heart
-age related calcification, congenital defects
what is auscultation & give examples?
medical technique that involves listening to internal sounds within the body using a stethoscope
eg heart sounds- sub-dub, lung sounds during breathing
