Vessel Wall 101
This is the innermost blood vessel layer, lined by endothelial cells and directly facing the blood.
What is the tunica intima? Blood vessels have tunica intima, media and externa/adventitia layers.
Put this pathway in order: veins, arteries, capillaries, venules, arterioles.
What is arteries → arterioles → capillaries → venules → veins?
Standard vascular flow proceeds from larger arteries to arterioles to capillaries and then back through venules and veins.
This circulation sends blood from the gut through the liver before it returns to the systemic circulation.
What is hepatic portal circulation?
This barrier is formed by specialised brain microvascular endothelial cells and tight junctions, with support from pericytes and astrocytic end-feet.
What is the blood–brain barrier?
This groin artery is the classic “workhorse” arterial access site for many endovascular procedures
What is the common femoral artery?
This vessel type generally has a thicker tunica media, more smooth muscle/elastic tissue, and handles higher pressure than its counterpart.
What is an artery?
This part of the vascular tree is where exchange is maximised because the total cross-sectional area is highest.
What are capillaries?
This portal system allows hypothalamic signals to reach the pituitary at high concentration.
What is pituitary, or hypothalamic–hypophyseal, portal circulation?
Compared with extracranial arteries, intracranial arteries generally have less of this outer supportive layer.
What is adventitia?
This wrist artery is increasingly used for neurointerventional access and may be helpful in difficult arch anatomy.
What is the radial artery?
These structures help veins prevent backward flow, especially when blood is returning from the limbs against gravity.
What are venous valves?
As blood travels from the aorta to the right atrium, this haemodynamic parameter continuously decreases.
What is blood pressure?
This circulation supports maternal–foetal exchange of gases and nutrients.
What is placental circulation?
Intracranial arteries generally lack this elastic layer that is more typical of many extracranial arteries
What is the external elastic lamina?
This common human arch variant has the left common carotid sharing a common origin with, or arising from, the brachiocephalic/innominate artery — although the term is a misnomer.
What is the so-called “bovine arch”?
This Latin term means “vessels of the vessels” and refers to small vessels that supply the walls of larger vessels.
What are vasa vasorum?
At any given moment, about this percentage of blood volume is in arteries, capillaries and veins, respectively.
What is about 30%, 5% and 65%?
How is portal circulation fundamentally different from normal systemic circulation?
What is blood passing through two capillary beds in series before returning to the systemic circulation?
These intracranial venous channels are endothelial-lined spaces between the periosteal and meningeal layers of dura mater.
What are dural venous sinuses?
During a stroke thrombectomy from femoral access, difficulty advancing catheters from the arch to the carotid circulation is more likely in patients with this aortic arch classification.
What is a Type III aortic arch?
A healthy artery loses blood supply to its vasa vasorum. Histologic studies suggest this layer would be most vulnerable to ischemic injury.
What is the middle third of the tunica media?
This is the main functional reason capillaries are thin-walled and slow-flow zones.
What is exchange of gases, nutrients and waste?
Larger vessel walls need their own blood supply because diffusion from the lumen is not enough for the outer vessel wall.
What is the purpose of vasa vasorum?
This is why many intracranial arteries are usually described as lacking distal vasa vasorum
What is that they are surrounded by nutrient-rich CSF and have different wall structure than extracranial arteries?
A stroke physician abandons femoral access because of a hostile arch and directly punctures the neck vessel supplying the anterior circulation. Which vessel was most likely accessed?
What is the common carotid or internal carotid artery (direct carotid access)?