Sympathetic Nerve Fibers That Innervate Blood Vessel Walls are Found

Question

Sympathetic nerve fibers that innervate blood vessel walls are found primarily in the
A) tunica intima.
B) tunica media.
C) tunica adventitia.
D) tunica externa.
E) tunica interna.

Accepted Answer

Sympathetic nerve fibers that innervate blood vessel walls are found primarily in the tunica media, which is the middle layer of the blood vessel wall composed of smooth muscle cells. These nerve fibers regulate the diameter of the blood vessel by controlling the contraction and relaxation of the smooth muscle cells.