Perivascular Sheath?

[RicSum]

Hello,

 

I have been trying to find info regarding the "perivascular sheath" but can not find a simple explanation anywhere.

 

A medical journal that I read some time ago said that when an artery is completely transected, vasospasm occurs and the artery then often retracts into the perivascular sheath.

 

I fully understand the concept of vasospasm, but have never heard of the perivascular sheath before.

 

Am I right to believe that it is similar to the carotid sheath - i.e a connective sheath which surrounds arteries? If so, do all arteries have such a sheath or only certain sized arteries?

 

Also, what exactly is the purpose of this sheath?

 

I look forward to any replies but please do not suggest googling "perivascular sheath", as I have already tried that but could not find a clear explanation.

 

Thank you all in advance.

[SMF]

I have not heard this term in reference to a specific structure and it isn't in Steadman's medical dictionary. It probably is just an anatomical description. All blood vessels have an outer connective tissue layer called the adventitia, and I suspect that this is what is referred to, but it could also refer to the larger regions of connective tissue that contain and protect larger arteries, veins, and nerves. SM

[ewmon]

Perivascular sheaths are the adventitial sheaths or the adventitia, which define/restrict the course that arteries, veins and nerves take through the body. I know it by the name tunica externa, and it's also known as the tunica adventitia. Adventitia do not exist for capillaries because they would interfere with the transfer of nutrients and wastes between the blood and tissues.

[Joshua201]

its usually refers to the adventitia of the blood vessels(excluding capillaries).