great vessels aorta and branches of the aorta in this video we'll talk about the
great vessels of the heart we'll also discuss the major distribution networks of the aorta
by region we'll outline the regions served by the common internal and external carotid arteries
and we'll discuss the major arterial branches of the thoracic part of the descending aorta
so the great vessels of the heart refer to any vein or artery that is connecting to the heart
veins conduct blood back to the heart arteries conduct blood away from the heart
so in this particular photograph we can see the superior portion of the heart
contained within the pericardium here are the lungs that are lateral to the heart
here is the ascending aorta going into the arch of the aorta here going into the
descending aorta and here are some of the branches of the arch of the aorta
what we can also see is that the venous
supply of the anterior thoracic here has been cut let me erase this to show you what i mean
so here and here are stumps from the left brachiocephalic vein this vein would have crossed
the superior mediastinum like so covering over these branches of the arch of the
aorta so the two brachiocephalic veins come together to feed into the superior vena cava
in terms of systemic circulation the major venous systemic root is the caval system
the cable system consists of all blood that flows into the superior and the inferior
vena cava the superior vena cava drains everything superior to the diaphragm the thorax the upper
limbs the head and neck the inferior vena cava drains everything inferior to the diaphragm
the abdominopelvic cavity and the lower limbs both of these veins converge in the right atrium
so systemic venous blood returns to the heart at the right atrium from the right atrium
blood is conducted through the tricuspid valve into the right ventricle
the right ventricle sends blood out through the pulmonary semilunar valve
into the pulmonary trunk keeping in mind this is deoxygenated blood
that pulmonary trunk divides into right and left main pulmonary arteries
and those pulmonary arteries conduct blood to the capillary beds of the alveoli of the lungs
where that blood picks up oxygen and dumps carbon dioxide oxygen is necessary for
chemiosmosis so that we can generate atp carbon dioxide is a byproduct of cellular metabolism
that richly oxygenated blood returns back to the heart through pulmonary veins now mind you these
pulmonary veins are conducting some of the most oxygenated blood in the body so we need to divorce
ourselves from the concept that veins carry deoxygenated blood and arteries carry oxygenated
blood that may hold true for the systemic loop but it falls apart for the pulmonary loop
that richly oxygenated blood from the pulmonary veins is delivered to the left atrium
the left atrium sends blood through an atrioventricular valve called the bicuspid
or mitral valve into the left ventricle the left ventricle then sends blood through the semilunar
aortic valve into the ascending aorta that ascending aorta then
goes into the arch of the aorta the arch of the aorta then feeds into the descending aorta
which has both thoracic and abdominal parts as we'll see now in this particular image here
we can see the superior vena cava we can see at least part of the ascending
aorta we can see the arch of the aorta and the beginning of the thoracic part of the
descending aorta coming off of this arch of the aorta we have typically three major vessels
there's the brachiocephalic trunk the left common carotid artery and the left subclavian artery
the brachiocephalic trunk bifurcates into the right common carotid artery
and the right subclavian artery so as you see we have two common carotid arteries
and two subclavian arteries and we'll discuss their major branches momentarily
so let's start at the very beginning of this story with the ascending aorta the ascending aorta
is conducting the blood from the left ventricle there is a valve there called the
semilunar aortic valve and just above the cusps of those valves are two sinuses
they're the coronary sinuses oftentimes referred to as the sinuses of valsalva now it's here
that we have the origins of the coronary arteries the coronary arteries are the arteries that supply
the heart with blood and there are two there is a left coronary artery
that we'll call the lca and a right coronary artery that we'll call the r ca
and over here on this image we can see there's the ascending aorta here is the lca
and there is the rca and you can see that these arteries have branches that take
themselves over the surface of the heart to supply the various muscular walls of the heart with blood
and we'll discuss those branches in detail when we discuss the heart
now as you recall that arch of the aorta has a brachiocephalic trunk
a left common carotid and then a left subclavian artery so the subclavian arteries can originate
either from the brachiocephalic trunk if you are the right subclavian artery
or the arch of the aorta if you are the left subclavian
artery the subclavian artery has three parts to it these are all relative to this muscle here
which is the anterior scalene muscle and this is the root of the neck so it's the transition
between the neck and the thorax in the upper limbs so the first part of the subclavian artery
is from there to there so everything that is medial to the medial edge of anterior scalene
is going to have three major branches one two three that we'll discuss in detail
when we discuss the upper limb the second part of the subclavian artery which is deep to this
anterior scalene muscle has one branch and then the third part of the subclavian artery which is
everything lateral to the lateral edge of anterior scalene out to the lateral margin of rib one also
has one branch so three one and typically one branches the subclavian artery is going to serve
the brain in the interior of the cranial cavity it's going to serve the neck it's going to serve
the thoracic wall and even the abdominal wall it's going to serve muscles of the neck and of
the shoulder and the continuity of the subclavian artery is known as the axillary artery which is
traversing the axilla which is then destined for the remainder of the upper limb
there are also as you recall common carotid arteries and these arteries on the right side
originated the brachiocephalic trunk and on the left side originate on the arch of the aorta
these common carotid arteries ascend the neck in the carotid sheath bound to the internal
jugular vein and also snuggled up with the vagus nerve which you can't see very well
it's behind this limb of ansys cervicalis there so that is vagus or cranial nerve 10.
these common carotid arteries bifurcate into internal and external carotid
arteries that i'll cover in detail in a subsequent video but suffice it to say
the internal carotid artery has no branches in the neck it ascends into the cranial cavity where it
supplies the brain with blood as well as helping to supply the spine with blood it's also going to
supply the orbit with blood and there will be branches that will come out of the orbit to supply
the the brow or the forehead with blood whereas the external carotid artery heading that way
supplies the neck with blood it supplies the face with blood it supplies the scalp with blood
and it has very many branches in the neck
so moving beyond the arch of the aorta we have the descending aorta so we can kind of see
there's the arch of the aorta coming around you know um and here is the thoracic aorta and it's
descending down the thorax just snuggled up adjacent to the esophagus that's right there the
thoracic part of the descending aorta or just the thoracic aorta has both visceral
and parietal branches the visceral branches are serving viscera the parietal branches are serving
the body wall now in this cartoonish transverse section we can get a sense for
the directionality of these branches so this way is anterior that way would be posterior
we can see that visceral branches tend to be more anteriorly oriented perhaps
not perfectly anteriorly oriented whereas parietal branches are more posterior lateral
in their orientation so i think that the parietal branches are going to be the easiest to understand
as these are intercostal arteries so they're coming out with
segmental regularity underneath the ribs so they are inter costal costa ribs um and
coming off of this thoracic part are intercostal arteries three through eleven the first and second
intercostal spaces are served by branches from the second part of the subclavian artery
so they're they're coming down from high whereas 3 through 11 are direct branches coming off of
the thoracic aorta below the 12th rib we have the subcostal arteries which are going out to supply
the lateral aspect of the thoracic and abdominal walls the abdominal aorta is going through or i
guess i should say it's partly surrounded by the vertebral column and the diaphragm at the
aortic hiatus which is about the t12 or the 12th thoracic vertebral level the diaphragm is a dome
and so it is going through the lowest level of that dome
some of the visceral branches include branches to the bronchial tree and portions of the parenchyma
of the lungs called the bronchial arteries typically there are two left and one right
bronchial artery the two left come directly off of the thoracic part whereas the one right bronchial
artery typically comes off of a left bronchial artery there can be several pericardial arteries
serves the pericardium as you can see someone has named these exquisitely well
there are also variably esophageal arteries to supply the esophagus with blood and then
finally these can be quite variable and they could be included in the parietal branches
superior phrenic arteries which supply the diaphragm with blood once
the aorta is on the other side of the diaphragm that descending aorta is known as the abdominal
part of the descending aorta or just the abdominal aorta and we'll also learn in
subsequent videos that there are inferior phrenic arteries from that abdominal part
and that leads us to the assessment question
which is the brachiocephalic trunk predominantly serves which areas of the body with blood
head neck and upper limbs that's that sounds pretty decent left head and neck uh
no let's see um brachiocephalic trunk supplies the right subclavian artery and the right common
carotid artery so anything with left in it is out so left out left out right head and neck
that's sounding pretty good i mean that's that's true it does do that um right head and neck
upper limb and portions of thoracic wall yeah there we go and we we know this because
the first part of the subclavian artery is going to have the internal thoracic artery supplying
the thoracic and even portions of the abdominal wall as well thank you very much for your time