Anterior and Middle Mediastinum Flashcards
1
Q
Anterior Mediastinum
- Boundaries
- Contents
- Thymus
A
- Body of sternum, pericardium, transverse thoracic plane and diaphragm
- Loose connective tissue, fat and lymphatics
- Makes the anterior mediastinum larger in children but regresses over time
2
Q
Middle Mediastinum
- Contents
- Adjacent structures/nerves
A
- Heart and pericardium, and roots of great vessels
- Great vessels, phrenic nerves and lung root structures
3
Q
Heart Position and Relations
- Heart position
- Phrenic nerves
A
- Slighty to the 1/3 right of sternum and left 2/3
- Right phrenic goes over right atrium, left phrenic goes over left atrium and ventricle. Nerves go down to diaphragm but also provide sensory fibres to pericardium. Root value is C3-C5.
4
Q
Fibrous Pericardium
- Description and borders
A
- Fibrous sack. Blends superiorly with the tunica adventitia of the great vessels, and posteriorly is continuous with the central tendon of the diaphragm.
5
Q
Serous Pericardium
- 2 parts
- Paricardial sinus
- Surrounds
A
- Visceral and parietal serous pericardium
- Formed by reflection of the pericardium
- Veins and arteries separately at their openings
6
Q
Ligamentum Arteriosum
- What is it?
- Useful for?
- Used to be?
A
- Fibrous remnant
- Locating the vagus nerve
- Rectus arteriosus which closes down after birth to become fibrous ligament
7
Q
Arterial Supply
- Origin of coronary arteries
- Right marginal branch runs?
- Blood supply to SAN?
- Left coronary artery almost immediately gives 2 branches - what are these?
A
- Base of aorta
- Along the right margin of the heart
- A branch of the right coronary artery
- Circumflex branch and the anterior interventricular descending brach.
8
Q
_Venous Drainage _
- Largest vein
- All drains to…?
- Exception to above is…?
A
- Great cardiac vein
- Coronary sinus, and from there to right atrium
- Anterior cardiac veins which just drain directly into the right atrium
9
Q
Right Atrium
- Impression in sinus venarum
- Muscles called…?
A
- Fossa ovalis
- Musculi pectinati
10
Q
Right Ventricle
- Muscular ridges in the wall
- Valves connected to and anchored by…?
- Moderator band
A
- Trabeculae carneae
- Tricuspid valves between right atrium and right ventricle connected to chordae tendineae and anchored to papillary muscles
- A shortcut for electrical signals
11
Q
Left Atrium and Ventricle
- Left atrium compared to right
- Left ventricle
A
- Almost entirely smooth walled
- Papillary muscles and such are still present in the left ventricle
12
Q
Innervation
- SAN
- AV node
- Cardiac plexus
- Parasympathetic contribution
- Sympathetic contribution
A
- Used by the ANS to regulate how fast the heart beats. Sits in the upper part of the crista terminalis.
- Allows signals to pass through it. Bundles together and then branches out into the walls of the ventricles and the papillary muscles.
- Recieves input from both the parasympathetic and sympathetic nervous systems
- Vagus nerve (X) going via intrinsic ganglia. Constricts coronary arteries and therefore reduces contraction force and heart rate
- T1-T5/6 levels. Going via cervical and superior thoracic paravertebral ganglia. Increases heart rate and contraction force by increasing blood flow through coronary arteries
13
Q
Fibrous Skeleton
- What does it provide?
A
- Support, and electrical insulation which allows for a delay between the contractions of the atria and ventricles.
14
Q
Valves
- Atrioventricular (AV) valves
- Semilunar (SL) valves
- Trileaflet
- Closing and coronary artery supply
A
- The bicuspid (mitral) valve, on the left side, and the tricuspid valve on the right. These valves are between the atria and the ventricles.
- The aortic valve, on the left side, and the pulmonary valve, on the right side. These valves are for arteries leaving the heart.
- All of the valves are trileaflet with the exception of the mitral valve.
- Backflow of blood causes the closure of the semilunar valves during diastole. As the blood flows back it naturally fills the coronary arteries at the base of the aorta.
