Veins and Fetal Circulatory Structures (Q3,P6) Flashcards
Venous plexuses
Multivein Bundles
3 Unique Patterns of Venous Drainage
- Dural Sinuses
- Hepatic Portal System
- Azygos System (veins)
Dural Sinuses
- a group of sinuses or blood channels that drains venous blood circulating from the cranial cavity
- Drain most of the blood of the brain
- most veins of the brain drain into the intracranial dural sinuses
- Empty into the internal jugular veins
Names of the Dural Sinuses
- Superior and inferior sagittal sinuses
- Straight sinus
- Transverse sinuses
- Sigmoid sinus
Where are the Dural Sinuses Located?
Are located between the layers of cranial dura mater:
Periosteal layer (dura mater outer layer)
Sinuses
Meningeal layer (dura mater inner layer)
What sinus turns into the Internal Jugular Vein?
s-shaped sigmoid sinuses drain/become the internal jugular veins
Brachiocephalic Veins
- A pair of large veins deep in the upper chest.
- Each brachiocephalic vein returns blood to the heart from the head, neck, arm, and chest
Superior Vena Cava
Returns blood from body regions superior to the diaphragm
Inferior Vena Cava
Returns blood from body regions inferior to the diaphragm
Where do the Superior and Inferior Vena Cava empty?
Empty into the right atrium
Veins of the Head and Neck
- Internal jugular veins
- External jugular veins
- Vertebral veins
Internal Jugular Veins Location
- at the top (superiorly), lies lateral to the internal carotids,
- lower down (inferiorly), it lies lateral to the common carotids.
What does the Internal Jugular Vein Become?
At the base of the neck, the internal jugular vein joins (and empties into) the subclavian vein, to form the brachiocephalic vein.
External Jugular Veins
- Superiorly, its tributaries drain the posterior scalp, lateral scalp, and some of the face
- Descends through the neck on the surface of the SCM.
- Empty into the subclavian drain
Does the External Jugular Veins have an accompanied artery?
Are not accompanied by any corresponding artery.
Where do the Vertebral Veins Begin and End?
C1-C6. At C6, they become one vein and later join the brachiocephalic vein
- Originating inferior to the occipital condyle, each vertebral vein descends through the transverse foramina of vertebrae C1-C6 in the form of a venous plexus;
- exit from C6 as a single vein, continue inferiorly to join the brachiocephalic vein in the root of the neck.
What do the Vertebral Veins Drain?
- Unlike the vertebral arteries, the vertebral veins do not serve much of the brain.
- Drains the cervical vertebrae, cervical spinal cord, and muscles in the superior neck region.
Deep Veins of the Upper Limbs
- Follow the paths of companion arteries
- Have the same names as the companion arteries
Superficial Veins of the Upper Limbs
- larger than the deep veins
- Visible beneath the skin
- Many anastomoses
- 4 Veins: Cephalic vein, Basilic vein, Median cubital vein, Median antecubital vein of the forearm
Cephalic Vein
- starts at the lateral side of the dorsal venous network (backside of the hand), bends around the distal radius to enter the anterior forearm
- Then ascends through the anterolateral side of the entire limb and ends inferior to the clavicle, where it joins the axillary vein
Basilic Vein
- arises from the medial aspect of the hand’s dorsal venous network, then ascends along the posteromedial forearm and the anteromedial surface of the arm.
- In the axillary region, the basilic vein joins the brachial vein to become the axillary vein.
Median Cubital Vein
- on the anterior aspect of the elbow joint, in the region called the antecubital fossa,the median cubital vein connects the basilic and cephalic veins.
- Often used for a blood draw or IV line
Median Vein of the Forearm
- ascends in the center of the forearm;
- its termination point at the elbow is highly variable.
Veins of the Thorax
- Azygos vein
- Hemiazygos vein
- Accessory hemiazygos vein
Azygos System
- Drains intercostal spaces
- Empties into the superior vena cava
- Comprised of azygos vein, hemiazygos vein, and accessory hemiazygos vein.
Where does the blood from the intercostal spaces empty?
- Blood draining from the first few intercostal spaces empties into the brachiocephalic veins.
- Blood from the other intercostal spaces drains into a group of veins called the azygos system.
Azygos Vein
- Name means unpaired
- Ascends along the right or the center of the thoracic vertebral bodies.
- Receives all of the right posterior intercostal veins, plus the subcostal vein.
Where does the Azygos Vein empty?
At about the level of T4, the azygos arches over the great vessels that run into the root of the right lung and joins the superior vena cava.
Hemiazygos Vein
- Ascends on the left side of the vertebral column, corresponds to the inferior half of the azygos on the right.
- At about midthorax, the hemiazygos runs horizontally across the vertebrae and joins the azygos vein.
Accessory Hemiazygos Vein
Superior continuation of the hemiazygos.
Course along the right to join the azygos vein.
Veins of the Abdomen
- Blood returning from the abdominopelvic viscera and the abdominal wall reaches the heart via the inferior vena cava.
- Most venous tributaries of this great vein share the names of their corresponding arteries.
Hepatic Veins
- The right and left hepatic veins exit the liver superiorly and empty into the most superior part of the inferior vena cava.
- These veins carry all the blood that originated in the digestive organs in the abdominopelvic cavity and arrived via the hepatic portal system.
The Hepatic Portal System
- A specialized part of the vascular circuit
- Picks up digested nutrients from the stomach and intestines and delivers these nutrients to the liver for processing and storage. (Also picks up toxins)
- Series of vessels in which two separate capillary beds lie between the arterial supply and the final venous drainage
Tributaries of the Hepatic Portal Vein
- Superior Mesenteric Vein
- Splenic Vein
- Inferior Mesenteric Vein
Veins of the Pelvis and Lower Limbs
- Deep Veins: Share the name of the accompanying artery
- Superficial Veins: Saphenous Veins issue from the dorsal venous arch (frequent anastomoses)
Great Saphenous Vein
- empties into the femoral vein
- Longest vein in the body; ascends along the medial side to empty into the femoral vein just distal to the inguinal ligament.
Small Saphenous Vein
- vein empties into the popliteal vein
- Runs along the lateral side of the foot and then along the posterior calf. Posterior to the knee, it empties into the popliteal vein.
Fetal Circulation
All major vessels in place by month 3 of development
Differences between fetal and postnatal circulation
- Fetus must supply blood to the placenta
- Very little blood is sent through the pulmonary circuit
- Some blood is also shunted from the fetal liver
Umbilical Vessels - Fetal Circulation
- Umbilical vessels run in the umbilical cord
- carries blood to and from the placenta
Paired umbilical arteries - Fetal Circulation
branch from the internal iliac arteries and carry blood to the placenta to pick up oxygen and nutrients; after birth becomes the medial umbilical ligaments
Unpaired umbilical vein - Fetal Circulation
returns blood from the placenta to the fetus; after birth becomes the ligamentum teres (round ligament)
Ductus venosus - Fetal Circulation
shunts some blood away from the fetal liver; after birth becomes the ligamentum venosum
Foramen ovale - Fetal Circulation
a hole in the interatrial septum; after birth becomes the fossa ovalis
Ductus arteriosus - fetal circulation
a shunt from the pulmonary trunk to the aortic arch; after birth becomes the ligamentum arteriosum
