Now, we’ll take a look at the brachiocephalic
veins and their tributaries. We mentioned
earlier that the right and left first posterior
intercostal veins or tributaries, but now,
let’s take a look at some of the others. The
brachiocephalic veins in this illustration
are here for the right brachiocephalic vein.
Your left brachiocephalic vein is shown here
and again, it is longer than the right one.
The tributaries to point out will be the internal
thoracic vein, the inferior thyroid vein and
then the last one to reference will be the
left superior intercostal vein.
This slide demonstrates the internal thoracic
vein. It’ll be a right internal thoracic vein
and a left internal thoracic vein. The right
internal thoracic vein is shown here and it’ll
empty into your right brachiocephalic vein.
It’ll run and accompany the internal thoracic
artery. Your left internal thoracic vein is
running on the left margin of the sternum
and will empty blood into the left brachiocephalic
vein. The internal thoracic veins are going
to be formed by the union of the superior
epigastric veins and the musculophrenic and
these veins will convey blood from the territories
supplied by the arterial counterparts.
The left superior intercostal vein is going
to drain the more superior posterior intercostal
spaces on the left. And those spaces are typically
intercostal spaces 2 and 3. Once it does so,
it will form the left superior intercostal
vein that courses over the aorta, arch of
the aorta and then, will empty into the left
brachiocephalic vein. In addition, the left
bronchial vein would empty in to your left
superior intercostal vein. And then the left
superior intercostal veins are simply going
to drain the territory supplied by the posterior
intercostal arterial counterparts. And because
you have a left bronchial vein being a tributary,
you’ll have some blood being drained from
We also have inferior thyroid veins that are
tributaries of the brachiocephalic vein. And
we see those inferior thyroid veins located
here. They are going to dive posterior to
the manubrium, right in the vicinity of the
jugular notch that we see here. And then you
can see those inferior thyroid veins emptying
into the left brachiocephalic. These will
help drain blood from the esophagus, larynx,
trachea, as well as the thyroid gland and
parathyroid glands. The thyroid gland is here.
This would be the left one. The right portion
of that gland has been removed.
Now, we’re looking at the veins of the vertebral
column and there are venous plexuses that
are associated with the vertebral column.
There’s an external venous plexus and we see
some of the elements of the posterior venous
plexus on the anterior portions of the vertebral
bodies. And then we also have some components
of the external vertebral plexus that are
located along the posterior vertebral arch
components here. The internal vertebral plexus
is within the vertebral foramen, as we see
in through here. And then within the body
of the vertebra, you can see some fairly significant
veins that will then join and empty into the
internal venous plexus and this large vein
that comes out of the vertebral body is referred
to as the basivertebral vein. And then you
have interconnecting veins between the internal
venous plexus and the external venous plexus.
And these are the intervertebral veins. Blood
that makes its way into the external vertebral
venous plexus, this plexus does have anastomotic
connections or anastomoses with your posterior
intercostal veins. In addition, veins of the
spinal cord can drain into this system.
Now, we’re shifting our attention to a structure
that makes a brief appearance in the thoracic
cavity and this venous structure is your inferior
vena cava. Most of it lies within the abdominal
cavity, within the retroperitoneum and once
it enters the thoracic cavity by passing through
the caval hiatus in the diaphragm, it will
do so at vertebral level T8. It’s going to
be a very, very short venous structure because
the right atrium is there to receive it. So,
it’s only about 2.5 cm in length within the
thoracic cavity. And we do see the cut edge
of the inferior vena cava here and where it’s
cut, it’s been cut from the right atrium.
That now brings us to our summary slide. So,
what are some of the key take-home messages
from this lecture?
First, branches of the pulmonary trunk and
branches (direct and indirect) of the aorta
supply thoracic structures.
The aorta within the thorax is divided into
the following parts: ascending, arch and descending
(the thoracic portion).
The aortic arch normally gives rise to three
branches, though variations may be present.
And pulmonary veins and tributaries of the
azygos vein drain most of the thoracic structures.
Thank you for joining me on this lecture on
arteries and veins of the thorax.