Mediastinum and Heart: Content and Organization

Question 1

Boundaries

Answer 1

Posterior: Vertebral column
Anterior sternum and cartilage 
Lateral: pleura 
inferior: diaphragm 
Superior: thoracic inlet

Question 2

Mediastinum: Superior

Answer 2

Great vessels of the heart, thoracic duct (left), (cardiac, pulmonary, esophageal) autonomic nerve plexuses, recurrent laryngeal nerves, esophagus, thymus, azygos system, parts of trachea

Question 3

mediastinum: Inferior, anterior

Answer 3

Anterior: lymph tissue, fat

Question 4

Mediastinum: Inferior, posterior

Answer 4

Posterior: pulmonary arteries and veins, thoracic aorta, azygos veins, sympathetic trunk + thoracic splanchnic nerves, thoracic duct

Question 5

Mediastinum: Inferior, middle

Answer 5

the heart and its pericardial tissues

Question 6

Vagus and laryngeal recurrent nerves: how and where do they go

Answer 6

RIGHT vagus anterior to brachiocephalic trunk but posterior to R. brachiocephalic vein/L. brachiocephalic vein

LEFT vagus runs anterior to arch of the aorta and posteriorly to the left subclavian vein

LEFT recurrent laryngeal nerve runs posteriorly to arch of the aorta, loops under it and behind the ligamentum arteriosum to connect with the vagus nerve

Question 7

Considering the midline of the body, where is the heart located?

Answer 7

left of the midline, posterior to sternum, middle of mediastinum

Question 8

How is the heart positioned in the middle of the mediastinum?

Answer 8

Rotated such that right side (Right atrium and ventricle) is located more anteriorly

left side is located more posteriorly

Question 9

posteriosuperior surface of the heart =

Answer 9

formed primarily by left atrium, called the base

Question 10

What vessels enter the left boarder of the base of the heart?

Answer 10

pulmonary veins

Question 11

the apex points

Answer 11

slightly anteroinferiorly toward left side of the body

Question 12

posterior spatial relationships between vessels

1. pulmonary veins to pulmonary arteries
2. pulmonary arteries to aorta
3. aorta to brachiocephalic vein

Answer 12

from anterior to posterior to inferior (front of the heart to the back of the heart to the midline of the heart)

1. bilateral pairs of pulmonary veins are inferior to pulmonary arteries
2. pulmonary arteries are inferior, posterior to arch of the aorta, diverge into L (one vessel) and R (two vessels) on either side

Question 13

Pericardium

Answer 13

fibrous, serous sac

held in place within the mediastinum by connective tissue that supports the great vessels external walls superior to the heart and the diaphragm

outer portion is touch, dense connective tissue layer called the fibrous pericardium

Question 14

Fibrous pericardium

Answer 14

dense connective tissue layer called the fibrous pericardium

attached to both the sternum and diaphragm

Question 15

Functions of the pericardium

Answer 15

restricts heart movement so it doesn’t bounce and move in the thoracic cavity

prevents heart from overfilling with blood

Question 16

Inner pericardium

Answer 16

serous pericardium

Question 17

Layers of the pericardium

Answer 17

Epicardium: visceral layer of serous pericardium

myocardium

Endocardium

Question 18

The older we get, more fat deposits in what part of the heart?

Answer 18

the epicardium

Question 19

the thickest muscle layer in the heart is the

Answer 19

myocardium

Question 20

the muscle surface in the heart is the

Answer 20

endocardium

Question 21

the endocardium covers the

Answer 21

internal surface of the heart and valves, as well as the external surface of the valves

Question 22

between the myocardium and the endocardium is a layer called

Answer 22

the subendocardial layer, composed of areolar connective tissue

Question 23

External anatomy

Answer 23

artria separated from ventricles externally by the coronary sulcus, extends around circumference of the heart

anterior/posterior interventricular sulcus are located between left/right ventricles

these sulci extend inferiorly to the apex of the heart

Question 24

Functions of the Fibrous skeleton

Answer 24

separates ventricles from atria

anchors heart valves by forming supportive rings of attachment

provides electrical insulation between atria and ventricles

insulations ensures muscle impulses are not separated at random, preventing heart chambers from beating at the same time

provides rigid framework for attachment of cardiac muscle tissue

Question 25

Right atrium (from memory)

Answer 25

receives blood from IVC/SVC, coronary sinus, has pectinate muscle and separated from Left Atria via interatrial septum

Question 26

Right Ventricle (from memory)

Answer 26

interventricular spetum separates R/L ventricles has three papillary muscles which anchor the chordae tendineae

Question 27

Left atrium

Answer 27

posterior wall contains four openings for pulmonary veins anterior wall contains small amount of pectinate muscle, and an auricle

Question 28

Left ventricle

Answer 28

largest of the four chambers wall is 3 times thicker than Right ventricle because it is supplying blood to the systemic circuit trabeculae carneae in the left are more prominent TWO papillary muscles attach to chordae tendineae

Question 29

Pulmonary trunk

Answer 29

superior end narrows into smooth walled, conical region called conus arteriosus marks end of right ventricle and entrance of the pulmonary trunk

Question 30

conduction system of heart

Answer 30

possesses autorhythmicity contractile muscles in the myocardium

Question 31

Sinoatrial node and atrioventricular node

Answer 31

Sinoatrial node is located in the posterior, superior wall of the right atrium below the superior vena cava the atrioventricular node is located between the floor of the AV valve and the coronary sinus

Question 32

path of conduction

Answer 32

SA node --> AV node --> bundle of His ---> purkinje fibers --> spreads from apex throughout ventricular myocardium

Question 33

Innervation of the heart

Answer 33

symp/parasym via cardiac/coronary plexus sym INCREASES rate and force of heart contractions parasym decreases rate, but HAS NO EFFECT ON FORCE OF CONTRACTION, except in special circumstances

Question 34

Coronary circulation

Answer 34

L/R coronary arteries travel in coronary sulcus (atrioventricular groove) of heart to supply heart wall Right coronary artery branches into marginal artery, supplies right border of the heart posterio

Question 35

marginal artery

Answer 35

branches from the right coronary artery supplies the right border of the heart

Question 36

Posterior interventricular artery

Answer 36

branches from the right coronary artery | supplies both left and right ventricles

Question 37

Left coronary artery branches into

Answer 37

anterior interventricular artery | circumflex artery

Question 38

LAD

Answer 38

left anterior descending artery, branches from left coronary artery supplies anterior surface of both ventricles and interventricular septum

Question 39

circumflex artery

Answer 39

supplies left atrium and ventricle

Question 40

cardiomyopathies (two kinds)

Answer 40

dilated cardiomyopathy left ventricle weakened, struggles to pump enough blood to meet the body's needs hypertrophic myopathy left ventricle does not fully relax between heartbeats