Mediastinum And Heart

Question 1

What limits the central compartment of the thoracic cavity?

Answer 1

Connective walls that separate this central region from the pleural cavities on either side
-it is continuous anteriorly/posteriorly from sternum and costal cartilages to the bodies of the vertebrae

Question 2

Describe the superior portion of mediastinum

Answer 2

• continuous with thoracic aperture

- attached inferiorly to the diaphragm

Question 3

-Inferior part of mediastinum is subdivided into?

Answer 3

Anterior, middle, and posterior regions

Question 4

What are the regions of the inferior part of the mediastinum separated by?

Answer 4

Pericardium (connective tissue)

Question 5

What are the thoracic viscera located within the mediastinal regions?

Answer 5

• esophagus
• trachea
• bifurcation to the primary bronchii
• heart
• origin of the great vessels

Question 6

What part of the mediastinum is the pericardium?

Answer 6

Middle region of the inferior part of the mediastinum

Question 7

What does the pericardium consist of?

Answer 7

-2 layers (tough outer latter and inner serous layer)

Question 8

What tissue type is the tough outer layer of the pericardium?

Answer 8

Dense irregular CT

Question 9

What type of epithelium is the inner serous layer of the pericardium?

Answer 9

Simple squamous epithelium (mesothelium)

Question 10

What is the pericardium continuous with?

Answer 10

• the tunica adventitia of the great vessels

- cervical fascia

Question 11

Parietal epicardium

Answer 11

• it is the inner layer of mesothelium

- it is reflected onto the heart as the visceral epicardium or outermost layer of the heart

Question 12

What is the visceral epicardium adhered to?

Answer 12

The muscular myocardium (heart muscle)

Question 13

How many layers of tissue is the heart made up of?

Answer 13

3

• visceral epicardium (outermost)
• myocardium
• endocardium (innermost)

Question 14

What is the myocardium made up of?

Answer 14

Cardiac branched striated muscle

Question 15

How are cardiac sarcomeres attached to each other?

Answer 15

• gap junctions

- Intercalated discs-allows for contraction in a widespread fashion

Question 16

Functions of the fibrous skeleton of the heart:

Answer 16

• supports integrity of cusps and valves

- “insulator” of electrical activity allowing for directing of the depolarizing wave to the AV node `

Question 17

How does depolarizing wave spread from SA node to atria?

Answer 17

Gap junctions allow for spread of calcium

Question 18

Myogenic spread is limited to the atria by?

Answer 18

The fibrous skeleton

Question 19

Flow of deploarizing wave

Answer 19

SA node-atria-AV bundle (bundle of His), ventricles

Question 20

Papillary muscles

Answer 20

• contract first in order to stabilize the 2 AV valves to resist prolapsed and regurgitation of blood back into atria
• have strong connective tissue attachments to the CT of the cusps of AV valves (chordae tendinae)

Question 21

Muscular fiber ridges

Answer 21

• mark the atrial and ventricular walls

- assist in complete contraction of walls of chambers

Question 22

Pectinate muscles

Answer 22

-mark the thin walled atria

Question 23

Trabeculae carneae

Answer 23

Mark the thicker ventricular walls

Question 24

Chordae tendinae

Answer 24

Attach papillary muscles to the cusps of the AV valves

Question 25

Where do the openings of the coronary arteries lie?

Answer 25

Behind the left and right cusps of the aortic valve

Question 26

What are the primary branches of the L coronary artery?

Answer 26

- anterior interventricular artery (LAD) | - circumflex branch of the LCA

Question 27

What are the branches of the right coronary artery?

Answer 27

- marginal branch (travels along the right ventricle) | - terminal posterior interventricular branch

Question 28

Coronary veinous drainage

Answer 28

- drainage parallels the arterial supply - Great cardiac vein in the interventricular groove (anterior) - Middle cardiac vein in the interventricular groove (posterior)

Question 29

Cardiac sinus

Answer 29

- lies in the right AV sulcus posteriorly and drains into right atrium - small cardiac vein and marginal branch of RCA drain here

Question 30

What closes the aortic valve cusps?

Answer 30

The elasticity of the aorta pushing blood back toward the valve

Question 31

Closing of aortic valve causes what to happen?

Answer 31

-blood pools in the aortic sinuses of the L and R aortic cusps

Question 32

Elastic pressure causes what to occur?

Answer 32

Perfusion (flow or spread) of arterial blood into the coronary vessels

Question 33

Fossa ovale

Answer 33

- remnant of fetal circulation - goes from R atrium to L atrium - blood didn't need to go to lungs since it came oxygenated from placenta