Theme 1: Lecture 3 - The Middle Mediastinum Flashcards
What is the anterior border of the middle mediastinum?
Anterior pericardium
What is the posterior border of the middle mediastinum?
Posterior pericardium
What is the lateral border of the middle mediastinum?
Mediastinal pleura
What is the inferior border of the middle mediastinum?
Diaphragm
What is the superior border of the middle mediastinum?
Transverse thoracic plane or level T4/5 or sternal angle
What are the contents of the middle mediastinum?
- Heart and pericardium
- Ascending aorta
- Pulmonary trunk and arteries
- Pulmonary veins
- Nerves (cardiac plexus and phrenic nerves)
Atrioventricular groove
Groove on the surface of the heart between atria and ventricles
Interventricular groove
Groove on the surface of the heart that divides the two ventricles
What are the auricles?
Flap over the surface of the heart that allows for extra blood volume to enter the atria
Which part of the aorta is in the middle mediastinum?
The ascending aorta
Describe the pulmonary trunk
- Deoxygenated blood leaves the heart via the pulmonary trunk
- Branches into the left and right pulmonary arteries
- Enters the hilum/root of the lung
Describe the pulmonary veins
- Oxygenated blood from lungs to left atrium
- Two veins from each side, left and right, inferior and superior
Describe the vena cava
- Blood enters the heart via the right atrium
- Receives deoxygenated blood from the superior and inferior vena cava
What are the 2 regions of the right atrium?
- Sinus venarum
- Pectinate muscle
What is the sinus venarum?
- Smooth walled muscle in the inner surface of the atria
- Often lies where the inflow and outflow of blood is occurring as the smooth surfaces allow for better blood flow
What is pectinate muscle?
- Parallel muscular columns in the inner surface of the atria
- Aids with contraction
Deoxygenated blood flows into the right atrium from the:
- Superior vena cava
- Inferior vena cava
- Coronary sinus
What is the coronary sinus?
The main vein that drains blood supplying the blood itself
What is the Crista terminalis?
The boundary between the sinus venarum and pectinate muscle
What are the landmarks used to identify the sinoatrial node?
- Superior part of the crista terminalis
- Junction of the superior vena cava with the right atrium
Describe the left atrium of the heart
Predominantly smooth walled but there is some pectinate muscle in the auricle
Moderator band
- Runs from the interventricular septum to the margin and is therefore only in the right ventricle
- Sometimes called the septomarginal band