Thorax IV Flashcards
The Cardiac Skeleton (attachment of the valves)
Collection of dense, fibrous tissue in the form of four rings which interconnect in a plane between the atria and ventricles
Purpose of cardiac skeleton
- Surround the AV orifices, aortic orifice and opening of pulmonary trunk
- Helps maintain integrity of openings and provides attachments for cusps
- Separates muscular wall of atria from ventricles, as well as electrically isolating the ventricles
What is the single connection between these two groups of myocardium
The AV bundle
The Cardiac Skeleton II
Papillary Muscles
- Muscles located in ventricles of the heart.
- Attach to the cusps of the atrioventricular valves (also known as the mitral and tricuspid valves) via the chordae tendineae
- Contract to prevent inversion or prolapse of these valves on ventricular contraction (systole)
Tricuspid Valve (papillary muscles/cusps)
How many papillary muscles in Tricuspid Valve
3 papillary muscles in right ventricle
Anterior: largest
Posterior: may consist of 1-3 structures
Septal: inconsistent (small or absent)
Septomarginal trabecula (moderator band)
- Bridge between lower ventricular (interventricular) septum and base of anterior papillary muscle
- Carries a portion of the cardiac conduction system to anterior wall of right ventricle
The mitrial valve
No Septal papillary
The Semilunar Valves
Major Arteries of the Thorax: Aorta
1 . Ascending Aorta remains within the ______ ___
- Arch of Aorta:
- Lies behind the ______ _______, in front of ______. It arches ______ and backwards. It becomes ________ with descending aorta at level of _____ angle - Aortic arch branches:
- ________ _______(divides into right _____ and right common ____)
- Left common ______
- Left _______
- Ascending Aorta remains within the pericardial sac
- Arch of Aorta:
- Lies behind the manubrium sternum, in front of Trachea. It arches upwards and backwards. It becomes continuous with descending aorta at level of sternal angle - Aortic arch branches:
- Brachiocephalic trunk (divides into right subclavian and right common carotid)
- Left common carotid
- Left subclavian
Mediastinum
Aortic Arch Branches
Features of the Descending Thoracic Aorta
- Begins at about T4-T5 from the arch of the aorta
- Descends in the posterior mediastinum
- Passes through the aortic hiatus of the diaphragm at T12
Descending Thoracic Aorta
Q: Why is it important that the Descending Thoracic Aorta passes through the aortic hiatus of the diaphragm at T12?
So that we don’t get compression of aorta by contraction of diaphragm
Descending Thoracic Aorta: Posterior Intercostal Arteries
Brachiocephalic
The Vena Cavae
All the body’s systemic veins (except cardiac) ultimately drain into either the superior vena cava (SVC) or inferior vena cava (IVC)
The superior vena cava receives blood from…
The head, neck, chest, shoulders and upper limbs
The inferior vena cava collects…
most of the venous blood from organs inferior to the diaphragm (execption Azygous Vein*)
*drains posterior abdominal & thoracic wall eventually into SVC
The azygous system of veins provides an alternative route for….
venous return back to the heart via the superior vena cava in cases where the inferior vena cava is damaged
The Azygous Vein
The Hemiazygos vein