Outer it is the network that forms by collagen fasciculus, be linked together with arachnoid Xiaoliang. 外层是由胶原纤维束组成的网，与蛛网膜小梁相连。
And blood-vessel of haemorrhage sex head is ill, if cerebral hemorrhage is mixed arachnoid haemorrhage finishing speech, also can cause sickness. 而出血性脑血管病，如脑出血和蛛网膜下腔出血，也都可引起呕吐。
