And finally, the outermost layer of your blood vessels is the tunica externa.

最后，你的血管的最外层是外膜。

The tunica externa also has nerve fibers, lymphatic vessels, and in the biggest vessels, the protein elastin.

外膜也有神经纤维、淋巴管，在最大的血管中也有弹性蛋白。

To make things really wild, some huge vessels have a tunica externa that's so thick that it needs its own blood supply.

神奇的是，一些大血管拥有非常厚的外膜，以至需要有自己的血液供应。

Finally, there's the tunica externa or outside tunic which is made up of loosely woven fibers of collagen protein that protect and reinforce the blood vessel and anchor it in place.

最后的外膜，由疏松结缔组织组成，含弹性纤维和胶原纤维，可保护和加固血管并使其固定。

So there are tiny blood vessels, called the vasa vasorum, which means vessels of the vessels that creep along the tunica externa to bring nutrients to specifically that layer of the blood vessel wall.

所以有些微小的血管，叫血管滋养管；拉丁语义为“血管的血管”：它们沿外膜走行，为血管壁提供营养。