Final answer:
Two smooth muscle layers surround the seminal gland: an inner circular layer and an outer longitudinal layer, both critical for ejaculation.
Step-by-step explanation:
The seminal gland (often referred to as the seminal vesicle) is surrounded by two layers of smooth muscle: an inner circular layer and an outer longitudinal layer. This musculature is part of the muscularis layer, which is commonly found in the walls of various organs.
The circumferential arrangements of the circular muscle fibers work to constrict the gland, while the longitudinal fibers help to shorten and widen it. These actions are critical during ejaculation, as they aid in forcibly propelling the semen along the reproductive tract. The smooth muscle layers, supported by a framework of collagenous fibers, are a standard organization found in the alimentary canal and other organs, including those of the male reproductive system, contributing to the functionality of these structures.
The two layers of smooth muscle surrounding the seminal gland are the circular layer and the longitudinal layer.