In the transerse scan the normal neural arch appears as a closed circle with an intact skin coering , whereas in spina bifida the arch is " u " shaped and there is an associated bulging meningocele ( thin - walled cyst ) or myelomeningocoele 在横切面上，正常神经弓表现为闭合的环，有完整的皮肤覆盖，然而在脊柱裂，弓变成“ u ”型，有相应的脑膜膨出（薄壁的囊型结构）或脊髓脊膜膨出。
