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Scribe: Brittney Wise
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Dr. Zehren
Structures of the Cardiovascular System
Page 1 of 8
NOTE: The notes that are found under the slide in the power point have been copied and pasted under each slide
in the transcript (they are italicized).
I.
II.
III.
IV.
V.
Introduction [S1]:
[S2] General Remarks
[S3] Components of the Cardiovascular System - Includes heart, arteries, vein, and capillaries.
[S4] Pattern of Blood Flow Through Heart - Not going to discuss this right now. He will cover this in the next hour.
[S5] Arteries carry blood away from the heart
a. Arteries are defined as vessels carrying blood away from the heart. Although they usually carry oxygen/nutrient
rich blood, this is not always the case. The pulmonary arteries would be a major exception (shown in blue).
Pulmonary arteries carry blood away from the heart but they have unoxygenated blood.
b. Arteries are said to branch. The lumen/diameter of the vessel gets smaller as you get to the level of the
arterioles which leads into the capillary beds.
VI. [S6] Veins carry blood toward the heart
a. Veins are defined as vessels carrying unoxygenated blood toward the heart. The pulmonary veins are carrying
oxygenated blood back to the heart.
b. Veins have tributaries not branches and they get larger and larger as they get closer to the heart.
c. Veins in the limbs are characterized by the presence of valves which ensure that blood only flows to the heart.
Other veins, like the hepatic portal vein for example, has no valves in it. So, veins may or may not have valves,
it depends on whether or not the venous flow has to work against gravity.
VII. [S7] Structure of Blood Vessels
VIII. [S8] Distinguishing Arteries from Veins
a. All blood vessels (with the exception of capillaries) have 3 layers in their walls. If we look at an artery and a vein
of about equal diameter we see that each has
i. Tunica intima (tunica = coat)
1. the innermost coat and is primarily endothelium
2. the integrity of this endothelium is important; if it’s torn that will interrupt blood flow and can lead to a
clot/thrombus formation
ii. Tunica media (middle layer) is smooth muscle which controls the diameter of the lumen and therefore the
blood pressure and the amount of peripheral blood reaching some area
iii. Tunica adventitia (outermost coat) is a connective tissue coat
1. In this layer there are both vessels and nerves
2. Many of the vessels that are here are going to the smooth muscle of the tunica media, making these
autonomic fibers controlling the tone in that muscle
3. There are also blood vessels in the tunica adventitia which supply the vessels itself. Unless the
vessel has an extremely thin wall like a capillary where it can get its own oxygen and nutrients
directly from the blood, vessels need their own blood supply and that is called the vasa vasorum (this
is an important term that means vessels of the vessel)
b. The thickness of the tunica media is the easy way that you can tell arteries and veins apart. Arteries have a
thicker tunica media than veins which gives them a much more rigid wall.
c. Capillaries are the vessels that unite the smallest arteries (arterioles) and the smallest veins (venules).
d. Capillaries only have a tunica intima, only an endothelial coat, which facilitates the exchange of oxygen and
nutrients. The exchange occurs at the level of the capillary beds. They form networks or a capillary bed (shown
in the diagram).
IX. [S9] Arterial System
X. [S10] Head and Neck
a. With regard to the head and neck the chief arteries are the common carotids and the vertebral arteries.
Remember that the right common carotid and the right subclavian artery branch off the brachiocephalic artery or
trunk which itself comes from the aortic arch.
b. On the left side the common carotid and subclavian arteries are independent branches that branch directly off
the aortic arch.
XI. [S11] Common Carotid Arteries and Vertebral Arteries
a. If we go and look at the distribution of the internal carotid arteries and vertebral arteries they are mainly
involved in supplying the brain.
b. Both the ICA’s and the vertebral arteries will come together at the base of the brain and form the arterial Circle
of Willis and this is what supplies the brain.
i. ICA - branches off and goes up through the temporal bone of the skull
Neuro: 1:00 - 2:00
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Monday, April 6, 2009
Proof: Laura Adams
Dr. Zehren
Structures of the Cardiovascular System
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ii. Vertebral arteries - branch off of the subclavian artery, pass through the transverse foramina of the cervical
vertebrae, merge from the uppermost cervical vertebrae, and pass into the skull through the foramen
magnum
c. The ICA has no branches in the neck and the only branch it has that distributes outside the head is the
opthalamic artery.
XII. [S12] Blood Supply to the Brain – (shared most of its information with slide 11)
XIII. [S13] External Carotid Artery and It’s Branches (“SALFOPSM”)
a. This has 8 branches in the neck and gets its name because it supplies to the outside of the skull.
XIV.
[S14] Upper Limb
XV.
[S15] Subclavian Artery and It’s Continuation
a. The chief artery of the upper limb is going to be the subclavian artery (artery shown in blue). The subclavian
artery will arch over the 1st rib (it is directly against the rib and can be compressed against it) and past the 1 st rib
it changes names and becomes the axillary artery.
b. The axillary artery has numerous branches that we won’t name that supply the axillary or armpit region. It then
continues until it reaches the lower border of this muscle, the teres major muscle, and it will change its name
again and will become the brachial artery because now it’s in the arm or brachium.
i. The brachial artery also has many branches and the only one that we will point out is the profunda brachii
artery or deep brachial artery. This is a fairly large artery that winds around behind the humorous and
supplies the posterior compartment of the arm, the muscles, and so forth. Since it is directly against the
bone it can easily be injured if you shatter your humorous at the mid-shaft level.
XVI.
[S16] Radial and Ulnar Arteries
a. The brachial artery will continue down in front of the elbow in the cubital fossa region where it will divide into 2
terminal branches, the radial and the ulnar. The radius is the bone on the lateral side of the forearm and the
ulna on the medial side.
i. Both of these have branches that will supply structures in the forearm.
ii. They both enter the palm of the hand and in the palm of the hand they form 2 arches:
1. The superficial palmar arch which is formed primarily by the ulnar artery.
2. The deep palmar arch which is formed primarily from the radial artery.
iii. From these arches precede other arteries that supply the digits.
XVII.
[S17] Thorax
XVIII. [S18] Blood Supply to Thoracic Wall
a. The thoracic wall itself is supplied by the intercostal arteries. These arteries run between the ribs.
i. Posterior intercostal arteries mostly come directly off the thoracic aorta as segmental branches that run
laterally and supply the tissues of the thoracic wall.
ii. The anterior intercostals arteries arise from the internal thoracic that comes off the subclavian.
b. The upper intercostal spaces receive their anterior intercostal arteries directly off the internal thoracic.
c. Lower down in the thorax, the lower intercostal spaces get their anterior intercostal arteries from a branch of the
thoracic called the musculophrenic.
d. What’s important to notice is that these anterior and posterior intercostals arteries anastomose with each other
in the intercostal space.
XIX.
[S19] Coarctation of Aorta
a. This is a condition where the aorta is severely constructed just beyond the point where the left subclavian
branched off.
b. It’s a congenital deformity.
c. You see the severe constriction and you might ask if this is compatible with life and it is. The reason that it is, is
because you have collateral circulation, essentially a bypass around that obstruction.
i. What happens over time is that the subclavian arteries begin to enlarge, the internal thoracic arteries which
are branches off the subclavian begin to enlarge, and the anterior and posterior intercostal arteries begin to
enlarge; the flow in the anterior intercostals arteries is lateral, away from the sternum (which is a normal
pattern of blood flow), but then when they anastomose with the posterior intercostals there is a reverse
blood flow in the posterior intercostal arteries.
ii. The posterior intercostals carry the blood back to the aorta distal to where the occlusion is, so there is just
a bypass to the point of obstruction allowing the lower part of the body to get adequate blood supply. Over
time these intercostal arteries get so large that they can be palpated on the chest wall and the pulsations of
those intercostal arteries can be felt and they can also erode the ribs as they get larger.
iii. Eventually this can be corrected surgically but a person can live for a number of years with this condition.
XX. [S20] Blood Supply to Heart (Coronary Arteries)
a. We will talk about the details of this in the next hour (so you can skip this slide and come back to it next hour).
XXI.
[S21] Pulmonary Trunk and Arteries
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a. He wanted to reiterate that there are 2 pulmonary arteries that spring from the pulmonary trunk which comes off
the heart. The right and left pulmonary arteries divide sort of like a “T” just below the concavity of the aortic
arch, going into the hialis (spelling?) of the lung on either side.
XXII.
[S22] Intrapulmonary Blood Circulation
a. If you look at a close up view, these little sac like structures are the alveoli where gas exchange occurs. They
are extremely thin walled. At each alveolus there is a capillary plexus aka an alveolar plexus. You can see that
the pulmonary artery carries unoxygenated blood to the alveoli.
b. After oxygenation the blood is collected via tributaries to the pulmonary veins which then return blood to the
heart.
c. These alveoli appear on what are called respiratory bronchioles. Proximal to the respiratory bronchioles where
there are no alveoli, those parts of the lung receive their own special blood supply. There is a special bronchial
circulation in addition to pulmonary circulation.
d. So, the non-respiratory parts of the lung, that is that parts that don’t have alveoli, need their own nourishment
and oxygen supply and that is supplied by the bronchial arteries which carry O2/nutrient rich blood to them and
bronchial veins which return that blood back to the systemic circulation.
XXIII. [S23]Abdomen
XXIV. [S24] Arteries of Anterior Abdominal Wall
a. The vessels of the abdominal wall: there are 4 major arteries that supply the anterior abdominal wall and they
are shown here.
i. The 2 terminal branches of the internal thoracic called the superior epigastric and the musculophrenic
arteries that are coming in from above.
ii. Coming in from below there is an inferior epigastric and a deep circumflex iliac artery which are both
branches of the external iliac.
b. Again, these anastomose with each other in the anterior abdominal wall.
XXV.
[S25] Arteries of Posterior Abdominal Wall
a. We see here the major vessel is the abdominal aorta which continues from the thoracic aorta.
b. It ends about the L4 vertebral level by dividing into the 2 common iliac arteries.
c. The branches of the abdominal aorta are usually classified as either being paired or unpaired, and either parietal
or visceral.
i. Parietal just means the same thing as somatic; it means that it supplies a structure on the body wall.
Visceral means that it goes to an organ.
d. The chief parietal branches of the abdominal aorta would be the inferior phrenic arteries, which come off almost
immediately as it enters the abdomen and supply the diaphragm, and then 4 pairs of lumbar arteries. These
lumbar arteries are segmental branches which are serially homologous with the intercostal arteries at a higher
level and they run laterally and supply the posterior abdominal wall.
e. The visceral arteries of the abdominal aorta, the paired visceral arteries, would include the renal arteries which
are going to the kidneys, and just below the renal arteries there is this pair of very slender arteries termed the
gonadal arteries (also known as the testicular or ovarian arteries). These gonadal arteries either descend to the
scrotum to supply the testis or to the ovus (spelling?), where they supply the ovaries. These gonadal arteries
arise high up on the posterior abdominal wall because during development the gonads descend and they drag
their nerve and blood supply with them (this is the reason for the high origin of these vessels).
f. There is one other pair of visceral arteries that arise directly from the abdominal aorta and they are known as
the middle suprarenal arteries.
i. These are small arteries and they go to the suprarenal gland which is an endocrine gland and it has a
tremendously rich blood supply.
ii. The middle suprarenal artery is just one of many suprarenal arteries. There are a whole series of superior
renal arteries which come off the inferior phrenic and there is usually a couple of inferior suprarenal arteries
which come off the renal artery.
iii. So, the superior and inferior suprarenal arteries supplement the middle suprarenal artery, but only the
middle suprarenal is the correct branch off the aorta.
XXVI. [S26] Arteries of Gastrointestinal Tract
a. In addition to all these arteries, we have 3 unpaired visceral arteries that come right off the front of the aorta.
These are the arteries that supply the GI tract:
i. celiac artery
ii. superior mesenteric artery (SMA)
iii. inferior mesenteric artery (IMA).
1. These are all unpaired and they all go to the GI tract.
b. Developmentally, the gut tube is divided into 3 parts (foregut, hindgut, and midgut) and each of these arteries is
associated with the foregut, midgut, and hindgut.
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Dr. Zehren
Structures of the Cardiovascular System
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c. When we take up the GI tract we will go into the branches of all of these arteries and the exact areas that they
supply but right now just appreciate that there are 3 visceral arteries supplying the different parts of the
embryonic gut.
XXVII. [S27] Pelvis and Perineum
XXVIII. [S28] Arteries of Pelvis (Internal Iliac Artery)
a. The chief artery of the pelvis and perineum is the internal iliac artery which is a branch of the common iliac
artery (there is an internal and an external branch of the common iliac artery).
b. The internal iliac has numerous branches. This is a very variable system in terms of the pattern of branching.
Woodburn’s Anatomy book says that the internal iliac system is the most variable system in the entire body.
c. There are differences (not that many) between males and females.
i. Basically re: branches of the internal iliac, whether they are direct branches off the internal iliac or indirect,
we have some that supply the pelvic viscera that would include arteries such as the …
1. Superior vesical arteries, (vesical in the pelvis means bladder) that supply the upper surface of the
bladder
2. Inferior vesical artery which is only found in males; this artery supplies among the prostate gland
below the bladder and the seminal vesicle behind the bladder
3. In the female, there are vaginal and uterine arteries
4. Both sexes have a middle rectal artery which goes to the mid part of the rectum
d. All of these are pelvic organs that are receiving their blood supply from the internal iliac.
e. However, this artery is much more extensive than just the pelvic viscera:
i. It has an obturator artery branch which leaves the pelvis and enters the thigh and supplies the medial part
of the thigh.
ii. It has 2 gluteal arteries (a superior and an inferior) which leave the pelvis and supply the buttocks area, the
hip region.
iii. There is an Iliolumbar artery which runs back up to supply the lower posterior abdominal wall.
iv. There is a lateral sacral artery which gives off branches to supply the contents of the sacral canal
v. Finally, is this internal pudendal artery that leaves the pelvis and enters the perineum which is an area
between the medial thighs that contains the external genitalia. So, internal pudendal is the chief artery of
the perineum having numerous branches itself which are not shown.
XXIX. [S29] Lower Limb
XXX. [S30] Femoral Artery
a. The femoral artery is the major artery of the lower limb. You can see that this is actually a continuation of the
external iliac artery. Once the external iliac artery crosses this boundary which is defined by the inguinal
ligament (fibrous tissue in the groin area) and passes posterior to that inguinal ligament it changes its name and
is now in the thigh and is called the femoral artery.
b. The femoral artery has a number of important branches, one is the deep femoral or profunda femoris artery
which parallels the femoral artery and gives off these perforating branches. These are arteries which run
posteriorly behind the femur and supply the muscles in the posterior compartment of the thigh, mainly the
hamstring muscles.
c. The other 2 branches of the femoral which are quite important are the medial femoral circumflex or medial
circumflex femoral and the lateral circumflex femoral. These arteries encircle the neck of the femur and
anastomose with each other. The medial femoral circumflex is of particular importance because the branches
coming off of it supply the head and neck of the femur.
d. If the neck of the femur is broken, there is a very good chance that the blood supply to the head and neck will be
compromised. This can lead to what’s called avascular necrosis of the head and neck of the femur. This is a
very common problem in elderly people, especially women with osteoporosis who have weak bones. This is
what happens when you hear of elderly people falling and breaking their hip.
i. This is somewhat misleading because what usually happens that the neck of the femur brakes first (not the
hip bone) and then they fall. Usually (unless the person is lucky) these vessels off the medial circumflex
artery that supply the neck and head of the femur will be torn and without adequate blood supply to the
head and neck they will become necrotic and this results in a necessary hip replacement.
XXXI. [S31] Popliteal Artery (Posterior View)
a. The femoral artery will continue into the back of the knee joint. It pierces a muscle called the adductor magnus
(there is an opening or a hiatus) and it changes its name again and now it is called the popliteal artery.
Poplitieal refers to the back of the knee.
b. There are also several (4) genicular arteries that come off by the knee joint.
XXXII. [S32] Arteries of the Leg and Foot
a. The popliteal artery will enter the leg and terminate by dividing into anterior and posterior tibial arteries.
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b. These arteries simply descend in the posterior compartment of the leg or the anterior compartment of the leg
and supply the muscles in those 2 compartments.
c. The posterior tibial artery will enter the sole of the foot and divide and divide into 2 plantar arteries. Plantar is a
term that means sole of the foot. You can see that the lateral plantar artery actually forms a deep arch in the
sole of the foot similar to the deep palmar arch in the hand.
d. The anterior tibial artery continues in front of the ankle joint and will become the dorsal artery of the foot or the
dorsalis pedis artery.
e. Often time clinicians will take a pulse of the dorsalis pedis artery to see if the anterior tibial is patent. If it is
patent then you should get a good pulse.
XXXIII. [S33] Venous System
XXXIV. [S34] Head and Neck
XXXV. [S35] Dural Venous Sinuses
a. The cranial cavity is primarily drained by these dural venous sinuses that are embedded in the dura mater.
Remember that all these venous sinuses are valveless and they are connected, at least some of them, with
veins outside the skull by means of emissary veins, which are tiny veins that penetrate the skull. Like the
venous sinuses, the emissary veins are valveless which allows a route for infection to spread from outside the
skull to the inside via these emissary veins.
b. Eventually this blood will accumulate at the base of the skull and be drained via the IJV.
c. Make sure to review this slide on your own.
XXXVI. [S36] Internal Jugular Vein (IJV) and Tributaries
a. This shows you the IJV as it descends in the neck. It is the largest veins in the neck. It begins as a continuation
of the sigmoid sinus and it ends at the root of the neck by uniting with the subclavian vein. So it’s logical to call
that larger vein formed by the junction of the subclavian vein and the IJV the brachiocephalic vein.
i. brachio = arm and cephalic=head
ii. The brachiocephalic vein drains the upper limb and head on that side.
iii. The 2 brachiocephalic veins unite to form the superior vena cava.
b. Again there are numerous tributaries of the IJV that you can review on your own.
XXXVII. [S37] Superficial Veins of Head and Neck
a. The main ones here would be the facial vein, the anterior jugular vein (draining the front of the neck), and the
external jugular vein (has a wide area of distribution.
b. The EJV will drain the scalp area, the deep infratemporal area, and even drain the shoulder area via these
tributaries it receives down here.
c. It finally terminates in the subclavian vein.
XXXVIII.
[S38] Upper Limb
XXXIX. [S39] Superficial Veins of Upper Limb
a. There are 3 superficial veins of the upper limb that you should know:
i. Basilic vein – begins on the dorsum (back) of the wrist; this vein ascends on the medial or ulnar side; tends
to remain superficial (in the superficial fascia just deep to the skin); this vein remains superficial until about
the mid-arm level and then it goes deep and continues up and eventually becomes continuous with the
axillary vein
ii. Cephalic vein – begins on the dorsum (back) of the wrist; this vein ascends on the lateral side of the upper
limb (the radial side); tends to remain superficial (in the superficial fascia just deep to the skin); the cephalic
remains superficial all the way up to the shoulder area and finally goes deep and terminates in the axillary
vein
iii. Median capital vein – connecting the basilic and cephalic vein; it connects them in front of the elbow; this
oblique cross channel is called the median cubital vein (look at the slide for a good visual)
XL. [S40] Axillary and Subclavian Veins
a. This slide is just showing you that there are deeper veins in the upper limb as well, and these veins usually
accompany the deeper artery. For example, the brachial artery which is deeply placed has a pair of deep veins
running with it called deep brachial veins or just brachial veins. You can see that they are joining the basilic vein
right here to form the axillary vein.
b. Here again you can see the termination of the cephalic vein going deep and ending in the axillary vein.
c. The axillary vein becomes the subclavian vein at the outer border of the 1st rib just like the artery.
d. So we have these deeper veins in the upper limb as well as the superficial veins.
XLI.
[S41] Median Cubital Vein and Venipuncture
a. This is the vein that connects the basilic vein with the cephalic vein in front of the elbow. Either this vein or the
cephalic or basilic, any of these veins can be used for venipuncture. They can be used for blood transfusions,
administration of drugs, or taking a blood sample.
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Dr. Zehren
Structures of the Cardiovascular System
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b. It’s important to realize that there are some pretty important structures related to these veins that can cause
some complications. In particular, if you look at this slide you can see that there are some cutaneous nerves.
c. There is a nerve here that runs parallel with the cephalic vein and is called the lateral cutaneous nerve of the
forearm and on the medial side there is a medial cutaneous nerve to the forearm that accompanies the basilic
vein. If a person is giving a venipuncture and should hit one of those nerves the patient is going to have a lot of
severe burning pain in the region of distribution of those cutaneous nerves. This is called paresthesia, meaning
an abnormal sensation (burning, tingling, that sort of thing).
d. Even more serious, if the needle goes to deep, there is a fibrous structure just deep to the medial cubital vein
called the bicipital aponeurosis (an aponeurosis is a flat tendon). The tendon of the biceps muscle is inserting
into the radius right about this region, but before it inserts it gives off this fibrous expansion called the bicipital
aponeurosis. That is all that separates this vein from these deeper structures namely the brachial artery and the
median nerve. These are 2 very important structures. If you were to damage the median nerve you would have
both sensory and motor problems with the forearm and hand because it’s a mixed nerve. If you hit the artery,
besides getting just hemorrhage, if you inject a drug into an artery that can have very serious consequences. It
can cause the artery to spasm and potentially you could lose your blood supply to the forearm and hand if a clot
formed or it if had a big enough spasm (this could result in necrosis).
e. This can also be called this the grace of God tendon, because the median nerve and the brachial artery are
spared/protected by this tendon when you give a venipuncture.
XLII.
[S42] Thorax
XLIII. [S43] Veins of Thoracic Wall
a. The veins draining the thoracic wall usually parallel the arteries.
b. You have anterior and posterior intercostals veins and the anterior intercostal veins are either direct or indirect
tributaries to the internal thoracic vein which goes to the brachiocephalic vein and back to the superior vena
cava.
c. The posterior intercostal veins, those on the right side of the body, most of them drain directly into this un-paired
vein called the azygos vain. You can see the azygos vein as it ascends along the vertebral column, and then
arches forward and empties its blood into the superior vena cava.
d. On the left side the drainage is a little more indirect. The posterior intercostal veins on the left side of the body,
drain first into either the accessory hemiazygos or the hemiazygos veins. Both of those veins themselves cross
the midline and empty into the azygos vein. So, ultimately, all the venous blood from the thoracic wall gets into
the superior vena cava and back to the heart.
XLIV. [S44] Veins of Heart (Cardiac Veins) (Anterior View)
a. We will take these up next hour.
XLV.
[S45] Pulmonary Veins
a. Just know that there are 4 of them: 2 on each side, superior and inferior. These are also valveless veins that
are returning oxygenated blood from the lungs to the left atrium of the heart (the base of the heart).
XLVI. [S46] Abdomen
XLVII. [S47] Veins of Anterior Abdominal Wall
a. Again the veins typically parallel the arteries. You have musculophrenic and superficial or superior epigastric
veins which are tributaries to the internal thoracic. We also have inferior epigastric and deep circumflex iliac
veins which drain to the external iliac. So, again there are veins corresponding to their arteries.
b. There are also superficial veins in the anterior abdominal wall just beneath the skin. Some of them around the
umbilicus anastomose with deeper veins, in particular what are called paraumbilical veins. He is going to come
back to this point later because it is of some importance (the anastomoses of the superficial veins of the
abdominal vein in the region of the umbilicus and the paraumbilical veins.
XLVIII. [S48] Veins of Posterior Abdominal Wall
a. The major vein here is the IVC (Inferior vena cava; aka “big blue”).
b. This is the largest vein in the body in terms of its diameter. It begins just a little more inferior than the aorta
about the L5 vertebral level and you can see it is formed by the union of the common iliac veins, the right and
left.
c. The IVC ascends on the posterior abdominal wall just to the right of the aorta. It finally penetrates the
diaphragm around the level of the 8th vertebra. It’s quite long and then immediately it enters the heart.
d. On its course in the abdomen the inferior vena cava receives a number of tributaries (listed below):
i. Inferior phrenic veins draining the diaphragm
ii. 4 pairs of lumbar veins from the posterior abdominal wall
iii. It also receives veins from the viscera lying on the posterior abdominal wall like the …
1. pararenal veins (you can see the long left renal vein crossing the midline and you can see the
shorter right renal vein)
2. the right gonadal vein (direct tributary to IVC)
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Structures of the Cardiovascular System
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3. the right suprarenal vein (direct tributary to IVC)
4. On the left side there is some asymmetry; the left suprarenal vein and the left gonadal vein don’t
drain directly into the IVC they go 1st into the left renal vein and then over to the IVC
XLIX. [S49] Veins of Gastrointestinal Tract (Hepatic Portal Vein)
a. There is another very important vein in the abdomen and this is the hepatic portal vein.
b. This carries blood from the GI tract including the pancreas, gall bladder, and the spleen.
c. The entire GI tract’s (plus the spleen’s) collected venous blood is transported to the liver via the hepatic portal
vein.
d. A portal vein is defined as a vein that begins in capillaries and ends in capillaries before the blood goes back to
the heart. The hepatic portal vein is collecting the blood from the capillary beds in the GI tract and it’s
transporting that venous blood to the liver, and in the liver that hepatic portal vein will break up into smaller veins
which at the capillary level are called hepatic sinusoids.
e. The blood then from the liver is then re-collected by hepatic veins which then empty directly into the vena cava.
So the vena cava doesn’t receive this blood from the GI tract directly, it has to go first through the liver via the
hepatic portal vein.
f. This is a huge system of veins. It’s estimated that about 1/3 of the total volume of blood in your body lies in this
hepatic portal system.
g. The 2 main tributaries of this are the splenic vein, which drains the spleen and the spleen itself is very vascular
organ, and the superior mesenteric vein. These 2 veins unite behind the pancreas to form the hepatic portal
vein. As you can see there are numerous tributaries draining into this portal system.
h. So, this blood, after you have eaten a meal all the products of digestion, other than fats which are absorbed in
the lymphatics, are carried to the liver via the hepatic portal vein so that he cells in the liver can metabolize
those products of digestion.
L. [S50] Hepatic Veins
a. Here you see the hepatic portal vein (a very large vein lying directly in front of the IVC) and it’s entering the liver
and branching and ultimately forms these liver sinusoids (capillary like structures in the liver), the blood is then
recollected by 2 or 3 large hepatic veins which drain the liver and empty directly into the IVC.
b. So, the hepatic portal vein carries blood to the liver and the hepatic vein carries blood away from the liver.
LI. [S51] Portal – Systemic Anastomoses
a. There are points where tributaries of the hepatic portal vein will anastomose with tributaries of either the
superior or inferior vena cava. These points of anastomoses are called portacaval or portal - systemic
anastomoses. These are important clinically.
b. The hepatic portal vein along with some of its tributaries are shown here on the slide in deep blue. Systemic
veins would be the superior vena cava and the inferior vena cava and their tributaries.
c. At various points there are areas where these tributaries anastomose.
i. For example, on the lower end of the esophagus right here you see that’s this tributary to the portal vein
anastomoses with this tributary of the azygos vein which itself drains to the superior vena cava. So, here is
one portacaval anastomoses on the lower esophagus.
d. Another one is down here on the rectum. The superior rectal vein which is a tributary of the portal system,
anastomoses with the middle and inferior rectal veins which are tributaries to the inferior vena cava.
e. There is another one around the umbilicus where the paraumbilical vein, a tributary to the portal vein,
anastomoses with the veins of the abdominal wall.
f. This is important clinically because when someone has portal hypertension, which means increased blood
pressure in the portal system (this can be due to liver disease, say cirrhosis of the liver which destroys the liver
tissue and makes blood flow through the liver difficult). Since the hepatic portal vein is valveless, the blood
backs up into the portal vein and all of it’s tributaries and can become greatly engorged, that blood tries to get
back to the heart via another route because it can’t get through the liver because it’s blocked. So, these small
anastomoses will enlarge and they may rupture causes severe bleeding. This can all be a consequence of
portal hypertension.
i. When these esophageal veins become enlarged and rupture it’s called esophageal varices and if they
rupture the person will vomit blood and this is critical because the person can lose a lot of blood.
ii. Rectal veins can also become enlarged and this is what hemorrhoids are.
iii. The veins around the umbilicus can enlarge. What happens here can be seen on the next slide.
LII. [S52] Caput Medusae
a. In Greek or Latin, caput means head and medusa was a character in Greek mythology and was the lady with
snakes coming out of her head. This resembles the head of medusa with these enlarge veins radiating out from
the umbilicus looking like snakes coming out of the head of the medusa. It could be the result of portal
hypertension which causes the veins to back up and try to get into the superior or inferior vena cava through
these anastomoses.
Neuro: 1:00 - 2:00
Scribe: Brittney Wise
Monday, April 6, 2009
Proof: Laura Adams
Dr. Zehren
Structures of the Cardiovascular System
Page 8 of 8
LIII. [S53] Portal – Systemic Shunts
a. What can be done in portal hypertension, surgically, is you can take the portal vein since it is right in front of the
vena cava, and they perform a side to side anastomoses. You take the portal vein and anastomose it with the
IVC and that blood can get direct backflow into the IVC. This is called a portacaval shunt.
b. Another thing that can be done is to remove the spleen, take the splenic vein and anastomose or suture it into
the left renal vein which is a tributary to the vena cava.
LIV.
[S54] Pelvis and Perineum
LV. [S55] Veins of Pelvis and Perineum
a. The internal iliac vein and likely the internal iliac artery is the chief vein draining the pelvis and perineum.
b. Many of the pelvic viscera have venous plexuses around them like the prostatic plexus. Although these venous
plexuses do drain to the internal iliac, they also communicate with veins in the vertebral canal (the internal
vertebral plexus).
i. This is important because these plexuses and these communications with the internal vertebral plexuses
are valveless. This means that if these pelvic organs become cancerous (like prostate cancer) if those
malignant cells enter the venous system they can metastasize via the venous system into the vertebral
canal and become embedded in the vertebral column or sometimes they can go all the way up into the
skull because the internal vertebral plexus communicates at the foramen magnum with the dural sinuses.
So, you can get prostatic cancer spreading up into the brain via this pathway.
c. Internal pudendal vein is one of the major tributaries of the internal iliac and this one drains the perineum.
LVI.
[S56] Lower Limb
LVII.
[S57] Superficial Veins of Lower Limb
a. Like in the case of the upper limb, you have superficial and deep veins.
b. There are 2 major superficial veins in the lower limb and they are called the great and the small saphenous
veins. (saphenous means “easily seen”).
i. Both of these veins begin on the dorsum of the foot.
ii. The great saphenous starts at the medial side of the foot and ascends along the medial side of the lower
limb all the way up to the groin area where it finally goes deep and empties into the femoral vein.
iii. The small saphenous vein begins on the lateral side of the foot and ascends in the back of the calf and
then goes deep and ends in the popliteal vein.
c. Both of these superficial veins have numerous valves to prevent backflow of blood working against gravity.
d. These superficial veins are also connected with deep veins of the leg via perforating veins.
LVIII.
[S58] Deep Veins of Lower Limb
a. The deep veins of the lower limb are again veins that go along with the deep arteries in the leg. We have a pair
of anterior and posterior tibial veins which drain the front and back of the leg. These veins unite in the knee
region forming the single popliteal vein which is quite large and very deeply placed. The popliteal vein ascends
through the adductor hiatus and becomes the femoral vein in the thigh and the femoral vein receives near it’s
termination the deep femoral vein and then it becomes the external iliac vein once it crosses behind the inguinal
ligament. So, pretty much this is just a reverse with what we saw with the arteries.
LIX.
[S59] End of Lecture
LX. [S60] The Renal Arteries … (answer is in bold)
a. assist in the supply of the suprarenal glands
b. are branches of the celia trunk
c. are branches of the superior mesenteric artery
d. are classified as paired parietal branches
e. none of the above is correct
LXI.
[S61] The brachiocephalic vein is formed by the junction of the … (answer is in bold)
a. Internal and external jugular veins
b. External jugular and subclavian veins
c. Internal jugular and subclavian veins
d. Internal jugular and axillary veins
e. External jugular and axillary veins
LXII.
[S62] The inferior vena cava … (answer is in bold)
a. Begins at vertebral level L5
b. Pierces the diaphragm at vertebral level T12
c. Lies to the left of the abdominal aorta
d. Receives the hepatic portal vein as a direct tributary
e. Contains numerous valves
[end 48:44 min]