![](/drem/stage18/labels/S70L.gif)
![head mesenchyme, isthmus of metencephalon, roof plate, root of trochlear nerve (CN IV), subarachnoid space, surface ectoderm, tectum of mesencephalon (M2), vascular plexus](/drem/stage18/Z0/S70N.jpg)
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Carnegie Embryo #4430 | Location: 2-32
Keywords: head mesenchyme, isthmus of metencephalon, roof plate, root of trochlear nerve (CN IV), subarachnoid space, surface ectoderm, tectum of mesencephalon (M2), vascular plexus
Source: The Virtual Human Embryo.