Heart and Mediastinum Anatomy Flashcards
systemic circulation
the circulation of the body as a whole bu separate from the pulmonary circulation
caval system
the venous side of the systemic circulation as it returns blood to the heart via the superior and inferior vena cavae
pulmonary circulation
circulation from the heart to the lungs and back
azygous system
system of veins (intercostals and hemizazygous veins) draining the thoracic wall converging on the azygous vein that drains into the superior vena cava
hepatic portal system
venous circulation from GI organ capillaries to the venous sinusoids of the liver via the portal vein and its branches
anastamosis
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
coelomic sacs
enclosed serous sacs that line the body cavities
visceral pleura lines the lung surface
parietal pleura lines the body wall
parietal pericardium
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
visceral pericardium
also known as the epicardium, the serous layer covering the fat/coronary vessels of the heart
cardiac tamponade
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
Describe the position of the heart in the thorax.
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
Describe the orientation of the heart in terms of its anterior, posterior boundaries as well as its right and left margins.
anterior - right ventricle
posterior - left atrium
right margin - right atrium
left margin - left ventricle
What parts of the lungs butt against the heart?
the middle lobe of the right lung and the lingula of the upper lobe of the left lung
Describe the bloodflow through the heart.
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
crista terminalis
crest between pectinate muscle and smooth posterior wall
it contains pacemaker tissue in addition to the sino-atrial node
fossa ovalis
remnant of the fetal foramen ovale, a blood shunt from right to left atrium
conus arteriosus
smooth top of the right ventricle tapering into the pulmonary semilunar valve
trabeculae carnae
“fleshy little beans” of muscle lining most of the ventricles
papillary muscles
specialized trabeculae stabilizing the atrioventricular valves via the chordae tendinae
prevents back swining of the vvalve cusps into the atria during ventricular systole
septomargiinal trabeculae
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
aortic vestibule
a structure of the left ventricle
the smooth upper part of the chamber equivalent to the conus arteriosus of the right ventricle
What prevents the semilunar valves from allowing backflow?
the blood-filled sinus between each valve cusp and arterial wall prevents the open valve cusps from sticking to the wall
Where is the best place to hear the aortic and pulmonary valves?
the 2nd intercostal space
Where is the best place to hear the tricuspid and mitral valves?
the 5th left intercostal space
Describe the arrangement of heart muscle and how this affects the contraction process.
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
What does the left coronary artery branch into?
anterior interventricular (LAD), circumflex, and left marginal branches
What heart structures does the left coronary artery supply?
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
What does the right coronary artery branch into?
marginal, nodal (right atrial), posterior interventricular (descending) branches
What heart structures do the right coronary artery supply?
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
left dominant circulation
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
coronary sinus
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
Where do the anterior cardiac veins drain?
directly into the right atrium
great cardiac vein
begins in the anterior interventricular groove and continues on as the coronary sinus
middle cardiac vein
joins the coronary sinus from the posterior interventricular groove
venae cordis minimae
smallest cardiac veins that connect capillary beds directly to heart chambers, and blood may flow in either direction
stellate ganglion
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
cardiopulmonary splanchnic nerves
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
parasympathetic innerveation of the heart
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
visceral sensory innervation of the heart
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
middle mediastinum
contains the heart and pericardium, beginning of the great vessels, primary bronchi, and the arch of the azygous vein
anterior mediastinum
contains fatty connective tissue, the remains of the thymus gland, deep parasternal lymph nodes, and the internal thoracid (mammary) vessels
posterior mediastinum
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
superior mediastinum
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
azygous system
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
