Anterior and Middle Mediastinum Flashcards
What vertebra is the superior mediastinum between
T1 and T5
What vertebra is the inferior mediastinum between
T5 and T9
What vertebra is the sternal angle at
T5
What are the 4 boundaries of the anterior mediastinum
- Body of sternum (anteriorly)
- Pericardium (posteriorly)
- Transverse thoracic plane (superiorly)
- Diaphragm (inferiorly)
What are the 3 main contents of the anterior mediastinum
- Loose connective tissue
- Fat
- Lymphatics
What anterior mediastinal structure is much larger in children
Thymus; turns into fat as you reach adulthood
What 3 structures are within the middle mediastinum
- Heart
- Pericardium
- Roots of great vessels
What 3 structures are adjacent to the middle mediastinum
- Great vessels
- Phrenic nerve
- Lung root structures
Where does the right phrenic nerve attach to the pericardium
Superficial to the right atrium
Where does the left phrenic nerve attach to the pericardium
Superficial to the left atrium and ventricle
What is the tunica adventitia of vessels
It is the outermost tunica of a blood vessel, surrounding the tunica media
What does the fibrous pericardium blend with inferiorly
It is continuous with the central tendon of the diaphragm
What does the fibrous pericardium blend with superiorly
Tunica adventitia of the great vessels
Name the layers of the pericardium, starting with the outermost
- Fibrous
- Parietal (serous)
- Visceral (serous)
Name the space in between the parietal and visceral pericardium
The pericardial cavity
Describe the location of the transverse pericardial sinus
Posterior to the pulmonary trunk, anterior to the SVC and superior to the atria
What is the oblique pericardial sinus
This is the space behind the heart
What are the 6 different sections of the heart
- Base
- Right border
- Inferior border
- Apex
- Left border
- Superior border
Describe what portions of the heart are in each of the different sections
Base = mainly left atrium
Right border = right atrium
Inferior border = right ventricle
Apex = left ventricle
Left border = left ventricle and left auricle
Superior border = right and left atria, and auricles
What runs through the coronary groove
Right coronary artery
What overlies the interventricular septum on the surface of the heart
Anterior interventricular groove
What 2 veins creates the SVC
Right and left brachiocephalic veins
Where does the ligamentum arteriosum attach to
At the superior end, the aorta; at the inferior end, top of the left pulmonary artery
What does the ligamentum arteriosum function as
Acts as the fibrous connection between the pulmonary trunk and the arch of the aorta
What nerve runs posterior to the ligamentum arteriosum
Left recurrent laryngeal
What are the 4 branches of the right coronary artery
- SA nodal
- AV nodal
- Right marginal
- Posterior interventricular
What are the 2 branches of the left coronary artery
- Circumflex (left marginal)
2. Anterior interventricular (diagonal)
What 4 sections of the heart does the right coronary artery supply
- Right atrium and most of right ventricle
- SA and AV nodes
- Posterior 1/3 of the IV septum
- Part of the left ventricle
What 4 sections of the heart does the left coronary artery supply
- Left atrium and most of left ventricle
- AV bundle
- Anterior 2/3 of the IV septum
- Part of the right ventricle
Describe where the cardiac veins drain to
All veins drain to the coronary sinus, except the anterior cardiac which drain directly into the right atrium
What arteries do they great, middle and small cardiac veins run alongside
Great = anterior interventricular Middle = posterior interventricular Small = right marginal
Describe the internal structure of the right atrium
One side is very muscular (musculi pectinati) and one side is very smooth (sinus venarum)
Where is the SA node located
Crista terminalis
What are the muscular ridges in the ventricular wall called
Trabeculae carneae
What conducting shortcut is unique to the right ventricle
Moderator band
Where do the chordae tendinae anchor at
The papillary muscles
What valve is located between the right atrium and ventricle
Tricuspid valve
Describe the internal structure of the left atrium and auricle
Very smooth and thin walled; auricle region has some muscular ridges
What valve is located between the left atrium and ventricle
Mitral (bicuspid) valve
How many pulmonary veins are flowing into the left atrium
Normally 4; 2 left and 2 right
What valves are shut at low pressure
Semilunar
What valves are shut at high pressure
Cuspid
How are the coronary arteries filled with blood
Due to the backflow of blood after the end of systole, as the heart muscle relaxes
What stops the cuspid valves from prolapsing
Papillary muscles contract as the ventricles do, so there is tension in the chordae tendinae (prevents prolapse)
What are the 2 functions of the hearts non-conductive fibrous skeleton
- Support for valves
2. Electrical insulation between atria and ventricles
Where does the SA node receive its innervation from
Autonomic innervation from the cardiac plexus (located between the arch of the aorta and the carina)
What is the function of the SA node
It is the heart’s pacemaker; it depolarises and sets the heart rate
