Heart and Mediastinum Anatomy

Question 1

systemic circulation

Answer 1

the circulation of the body as a whole bu separate from the pulmonary circulation

Question 2

caval system

Answer 2

the venous side of the systemic circulation as it returns blood to the heart via the superior and inferior vena cavae

Question 3

pulmonary circulation

Answer 3

circulation from the heart to the lungs and back

Question 4

azygous system

Answer 4

system of veins (intercostals and hemizazygous veins) draining the thoracic wall converging on the azygous vein that drains into the superior vena cava

Question 5

hepatic portal system

Answer 5

venous circulation from GI organ capillaries to the venous sinusoids of the liver via the portal vein and its branches

Question 6

anastamosis

Answer 6

connections between the small branches of two larger arteries or veins

it provides for collateral circulation between them if one is occluded

end arteries have no anastomoses such as renal arteries or the central artery of the retina of the eye

Question 7

coelomic sacs

Answer 7

enclosed serous sacs that line the body cavities

visceral pleura lines the lung surface

parietal pleura lines the body wall

Question 8

parietal pericardium

Answer 8

the sac that surroudns the heart with visceral and parietal serous layers that reduce friction as the heart beats

has a fibrous pericardium on the outside and a serous inner layer

Question 9

visceral pericardium

Answer 9

also known as the epicardium, the serous layer covering the fat/coronary vessels of the heart

Question 10

cardiac tamponade

Answer 10

compression of the heart from an abnormal collection of fluid in the pericardial cavity

fibrous pericardium has low compliance, so increased fluid accumulation increases pressure outside the heart

this restricts filling of the heart with blood

Question 11

Describe the position of the heart in the thorax.

Answer 11

spans anterior ribs 2-6, the length of the body of the sternum

a horizontal plane through the ventricles is at vertebral body T7/T8

Question 12

Describe the orientation of the heart in terms of its anterior, posterior boundaries as well as its right and left margins.

Answer 12

anterior - right ventricle

posterior - left atrium

right margin - right atrium

left margin - left ventricle

Question 13

What parts of the lungs butt against the heart?

Answer 13

the middle lobe of the right lung and the lingula of the upper lobe of the left lung

Question 14

Describe the bloodflow through the heart.

Answer 14

superior and inferior vena cava -> right atrium -> right atrio-ventricular (tricuspid) valve -> right ventricle -> pulmonary semilunar valve -> pulmonary trunk -> pulmonary arteries -> lungs -> pulmonary veins -> left atrium -> left atrio-ventricular (mitral or bicuspid) valve -> left ventricle -> aortic semilular valve -> aorta -> systemic circulation

Question 15

crista terminalis

Answer 15

crest between pectinate muscle and smooth posterior wall

it contains pacemaker tissue in addition to the sino-atrial node

Question 16

fossa ovalis

Answer 16

remnant of the fetal foramen ovale, a blood shunt from right to left atrium

Question 17

conus arteriosus

Answer 17

smooth top of the right ventricle tapering into the pulmonary semilunar valve

Question 18

trabeculae carnae

Answer 18

“fleshy little beans” of muscle lining most of the ventricles

Question 19

papillary muscles

Answer 19

specialized trabeculae stabilizing the atrioventricular valves via the chordae tendinae

prevents back swining of the vvalve cusps into the atria during ventricular systole

Question 20

septomargiinal trabeculae

Answer 20

ridges between the smooth conus arteriosus and the trabecular wall below

a significant one is the moderator band from the interventricular septum to the papillary muscles

Question 21

aortic vestibule

Answer 21

a structure of the left ventricle

the smooth upper part of the chamber equivalent to the conus arteriosus of the right ventricle

Question 23

What prevents the semilunar valves from allowing backflow?

Answer 23

the blood-filled sinus between each valve cusp and arterial wall prevents the open valve cusps from sticking to the wall

Question 24

Where is the best place to hear the aortic and pulmonary valves?

Answer 24

the 2nd intercostal space

Question 25

Where is the best place to hear the tricuspid and mitral valves?

Answer 25

the 5th left intercostal space

Question 26

Describe the arrangement of heart muscle and how this affects the contraction process.

Answer 26

the muscle layers are arranged in a spiral fashion, and contraction proceeds form the apex upwards, squeezing blood toward the AV valves like wringing a towel

Question 27

What does the left coronary artery branch into?

Answer 27

anterior interventricular (LAD), circumflex, and left marginal branches

Question 28

What heart structures does the left coronary artery supply?

Answer 28

most of the left atrium and ventricle anterior part of the right ventricle adjacent to anterior interventricular artery anterior 2/3 of the IV septum AV bundle branches in the septum

Question 29

What does the right coronary artery branch into?

Answer 29

marginal, nodal (right atrial), posterior interventricular (descending) branches

Question 30

What heart structures do the right coronary artery supply?

Answer 30

most of the right atrium and ventricle posterior part of the left ventricle adjacent to the posterior interventricular artery posterior 1/3 of the IV septum SA (60%) and AV (80%) nodes

Question 31

left dominant circulation

Answer 31

a variation where the left coronary artery gives rise to the posterior interventricular artery (fromt he circumflex, the anterior interventricular, or both) in addition to its typical branches

Question 32

coronary sinus

Answer 32

an endothelial-lined, venous channel _imbedded in heart muscle_ in the posterior atrioventricular groove rather than a typical, free-standing vein it drains blood from most of the heart into the right atrium

Question 33

Where do the anterior cardiac veins drain?

Answer 33

directly into the right atrium

Question 34

great cardiac vein

Answer 34

begins in the anterior interventricular groove and continues on as the coronary sinus

Question 35

middle cardiac vein

Answer 35

joins the coronary sinus from the posterior interventricular groove

Question 36

venae cordis minimae

Answer 36

smallest cardiac veins that connect capillary beds directly to heart chambers, and blood may flow in either direction

Question 37

stellate ganglion

Answer 37

the enlarged, star-shaped ganglion of the **sympathetic trunk** that supplies much of the heart and lungs it is the fusion of the **inferior cervical ganglion** and **T1 ganglion** sympathetics from the stellate ganglion and visceral sensory fibers that pass through it from T1 supply the ventricless

Question 38

cardiopulmonary splanchnic nerves

Answer 38

nerves that carry fibers from **lower cervical** and **upper thoracic** levels of the sympathetic trunk postsynaptic neurons whose _cell bodies are in the sympathetic trunk_

Question 39

parasympathetic innerveation of the heart

Answer 39

comes from the vagus nerve via the plexus on the bifurcation of the trachea the postsynaptic parasympathetic neurotransmitter acetylcholine functions on the SA node to slow the heart rate

Question 40

visceral sensory innervation of the heart

Answer 40

sensory fibers travel from the heart via the **cardiopulmonary splanchnic nerves** from the sympathetic trunk they travel in **communicating rami into the spinal nerves** and enter the **spinal cord via dorsal roots** cell bodies are in the **dorsal root ganglia**

Question 41

middle mediastinum

Answer 41

contains the heart and pericardium, beginning of the great vessels, primary bronchi, and the arch of the azygous vein

Question 42

anterior mediastinum

Answer 42

contains fatty connective tissue, the remains of the thymus gland, deep parasternal lymph nodes, and the internal thoracid (mammary) vessels

Question 43

posterior mediastinum

Answer 43

contains the esophagus, thoracic duct, azygous and hemiazygous veins, thoracic sympathetic trunk and splanchnic nerves, thoracic (descending) aorta, posterior intercostal arteries and nerves, and lymph nodes

Question 44

superior mediastinum

Answer 44

contains the great vessels, trachea, upper esophagus and thoracic duct, ,vagus and phrenic nerves, left recurrent laryngeal nerve, and upper part of the thymus gland

Question 45

azygous system

Answer 45

a system of veins that receives blood from the intercostal veins left posterior intercostal veins drain into the hemiazygous veins that pass over the vertebral bodies to join the azygous vein it arches over the root of the right lung to empty all intercostal blood into the superior vena cava