In both cases, the parasympathetic nerve fibers in the cavernosal spaces release acetylcholine from their nerve endings.

在这两种情况下，副交感神经纤维在海绵体间隙通过神经末梢释放乙酰胆碱。

Running down the centre of each corpus cavernosum is a large artery called the deep artery which gives off smaller arteries that supply the cavernosal spaces.

在每个海绵体的中心都有一条大动脉，称为深动脉，由它发出较小的动脉，为海绵体间隙供血。

This leads to a fall in intracellular calcium levels causing the smooth muscles to relax, and allowing the cavernosal spaces to expand and fill with blood.

这导致细胞内钙水平下降引起平滑肌放松，并允许海绵体间隙扩张及充满血液。