| • Science | • People | • Locations | • Timeline |
The layer of the artery that is in direct contact with the flow of blood is the tunica intima , commonly called the intima. This layer is made up of mainly endothelial cells. Just deep to this layer is the tunica media , known as the media. This "middle layer" is made up of smooth muscle cells and elastic tissue. The outermost layer (furthest from the flow of blood) is known as the tunica adventitia or the adventitia. This layer is composed of connective tissue.
Aneurysms are also described according to their shape: Saccular or fusiform . Aneurysms can be broken down into two groups: true aneurysms and false aneurysms. A true aneurysm involves an outpouching of all three layers of a blood vessel: the intima , the media, and the adventitia. True aneurysms can be due to congenital malformations, infections, or hypertension. A false aneurysm, also known as a pseudoaneurysm, involves an outpouching of only the intima.
Pseudoaneurysms can be due to trauma involving the intima of the blood vessel. Pseudoaneurysms are a known complication of percutaneousIn surgery, percutaneous pertains to any medical procedure where access to inner organs or other tissue is done via needle-puncture of the skin, rather than by using an "open" approach where inner organs or tissue are exposed (typically with the use of a arterial procedures.Aneurysms can occur anywhere where there is an artery. Most non-intracranial aneurysms (95%) arise distal to the origin of the renal arteries at the infrarenal abdominal aorta, a condition mostly caused by atherosclerosisAtherosclerosis is a disease of arterial blood vessels. Venous vessels are not involved unless surgically moved to function as an artery. Atherosclerosis is commonly referred to as a "hardening of blood vessels", but this is an over-simplification. Vascul. The thoracic aorta can also be involved. One common form of thoracic aortic aneurysm involves widening of the proximal aorta and the aortic root, which leads to aortic insufficiencyAortic insufficiency AI , also known as aortic regurgitation AR , is the leaking of the aortic valve of the heart that causes blood to flow in the reverse direction during ventricular diastole, from the aorta into the left ventricle. Aortic insufficiency.