The internal layer of the dura mater lies above the arachnoid mater and the two are separated by the subdural space.

硬脑膜的内层在蛛网膜之上，这两层中间的腔隙叫做硬膜下隙。

These two layers of the dura mater travel together, but at certain spots, the internal layer of the dura mater separates from the external one to form the meningeal folds.

两层硬脑膜共同运动，但在某些地方，硬脑膜内层和外层分开，形成一些脑膜折叠。

Looking at a cross-section of a bone, there's a hard-external layer known as the cortical bone and a softer internal layer of spongy bone or trabecular bone that is composed of trabeculae.

来看一根骨头的横截面，这个硬质的外层叫皮质骨，而软一些的松质骨内层，由骨小梁构成。