Cardiovascular and Mediastinum Flashcards
What is the mediastinum?
What are its divisions and demarkations?
Where is the heart located?
Mediastinum is the area that lies in between the lungs
It is divided into a
- superior and
- inferior mediastinum (at sternal angle)
- Inferior mediastinum further divided into
- anterior
- middle
- posterior
- Inferior mediastinum further divided into
The heart is located in the middle mediastinum (inferior mediastinum)
Where is the heart located?
In the middle mediastinum (of the inferior mediastinum)
What is the pericardium?
What are its layers?
The pericardium is a double-walled sac surrounding the heart
It is made of two layers:
- Fibrous pericardium
- Serous pericardium
- Parietal
- Visceral
What is the function (and disadvantages) of the different layers of pericardium?
Name the associated conditions
Fibrous Pericardium:
- tough, thick, protective
- protects from penetrating injuries
- prevent overfilling
but……
- haemopericardium: if the heart bleeds, the blood has nowhere to escape - the pericardial cavity fills with blood
- cardiac tamponade: the increased pressure squashes the heart and can prevent cardiac contraction - ability of heart to contract is reduced
Serous Pericardium:
- secretes serous fluid: membranous, glistening
- reflects back onto itself: parietal and visceral serous pericardium
Label the diagram
Describe the 3 layers of tissue
Epicardium
- visceral serous pericardium
Myocardium
- muscle layer
- main heart muscle
Endocardium
- internal lining
- continuous with endothelium of blood vessels connecting with the heart
Label the diagram and all the vessels
What is the pulmonary trunk?
What does it carry?
The pulmonary trunk from the right ventricle divides into right and left pulmonary arteries, one for each lung
It carries deoxygenated blood to lungs
What are the surfaces of the heart?
How does the heart lie in the anatomical position?
The heart has 3 surfaces:
- Anterior
- Base (Posterior) - opposite the apex
- Inferior - the part that sits on the diaphragm
Anatomical position: With its apex pointing towards the anatomical left
What is MI?
How is it described?
Myocardial infarction (MI) – irreversible death (necrosis) of part of the heart muscle (myocardium) due to blockage of it’s arterial blood supply (not venous blockage)
The “type” of MI is often described clinically according to which SURFACE of the heart has been affected, eg:
- Anterior MI
- Inferior MI
Label the diagram
Which part of the heart is supplied with blood?
Where do the coronary arteries arise from?
Which surface of the heart do they lie on?
Two coronary arteries (left coronary artery and right coronary artery) which arise from the ascending aorta (the first part of the aorta)
The first branch of the aorta is the coronary arteries: arise immediately after the aorta arises from the heart
They lie on the anterior surface of the heart
Describe venous drainage of the heart (name of vein and where it drains into)
Which part of the heart is being drained?
On which surface of the heart does the vein lie?
The Coronary Sinus: drains into the right atrium (not into IVC)
The venous drainage of the myocardium
Lies in between inferior/posterior surfaces of heart
What are the two circulation systems of the body and which side of the hearts are involved?
Systemic circulation and pulmonary circulation
Right side of the heart pumps deoxygenated blood from the systemic circulation to the pulmonary circulation
Left side of the heart pumps oxygenated blood from the pulmonary circulation to the systemic circulation
How many cardiac valves are there (and where)?
What is their function?
There are 4 cardiac valves (1 between each atrium and ventricle; and 1 between each ventricle and the vessel leaving it)
Their function is to ensure uni-directional blood flow
Name the cardiac valves and their location
- Bicuspid (Mitral) valve: between LA and LV
- Aortic valve: between LV and aorta
- Tricuspid valve: between RA and RV
- Pulmonary valve: between RV and pulmonary trunk
What is the function of the conducting system of the heart?
Label the diagram with locations/functions for each arrow
Label the diagram
Label the diagram (with the part of the body supplied)
Which part of the body do the branches of the aorta lie in?
The branches of the aorta lie in the superior mediastinum (above the sternal angle)
Label the diagram
Compare to the aortic branches
Compared to the aortic branches, the branches of the SVC have symmetry of the RHS and LHS
Label the diagram
Which side of the body can this vein be viewed on?
What is its function?
Azygous vein can only be viewed on the RHS
Azygous vein drains deoxygenated blood from the intercostal space (each intercostal vein drains into azygosvein which drains into superior vena cava)
It also connects the SVC and IVC and provides an alternative pathway for venous blood
Label the muscle and nerves and describe the nerve positions
Where are they found?
3 named nerves associated with the superior mediastinum. From lateral to medial:
- Phrenic: nerve supplying diaphragm: cervical spinal nerves C3,4,5
- Vagus: CN10 (cranial nerve 10)
- Recurrent laryngeal branches of the vagus nerve
