Diagram of the human brain showing the mesencephalon, or midbrain. The tectum forms the dorsal, or upper, surface of the midbrain. Inmammals, it is divided into two pairs of nuclei: the superior and inferior colliculi. The superior colliculi receive visual information, help coordinate rapid mov...
As is often the case in biology, things get stranger still. In females it’s not just the ovaries that are innervated by the vagus nerve, but part of the cervix and vagina as well. This was hypothesized by Komisaruk et al. (1997), based on the fact that some women with complete spi...
This one shows the whole cord, brainstem, thalamus, and cerebral cortex in coronal section, in cartoon form. It’s for drawing in ascending sensory and descending motor pathways, as shown in this office hours sketch. DC-ML is dorsal column/medial lemniscus, which carries discriminative touch ...
The difference is even more pronounced for primary sensory neurons, some of which run from your toe-tips to your brainstem, and which have somata as small as 0.02 millimeters across, or 1/100,000th of the length of their axons. In a 20-meter whale or sauropod, the axon of a primary ...
with interneurons in the brainstem, a pattern of neural architecture that is present in all extant vertebrates. The nerve cell bodies would have been located in the dorsal root ganglia adjacent to the spinal cord. The diagram of the neuron is based on Butler and Hodos (1996: fig. 2–1B)...
of the spinal cord could achieve orgasm from vaginal stimulation. Their fMRI study showed that the posterior part of the nucleus solitarius in the brainstem–which receives sensory fibers from the vagus nerve–was active in the process. I assume that there is some esoteric bit of embryology that...
) neurons responsible for sensing vibration or fine touch, which runs from the tip of his big toe to his brainstem. (NB: I have not actually dissected Andy to confirm this, or performed any viral neuron tracing on him, this is assumed based on comparative anatomy.) Here’s a diagram:...
of the arachnoid is thesubarachnoid space, where cerebrospinal fluid (CSF) circulates; this space is crossed by numerous strands of arachnoid that reach down to the pia, and which look like spiderwebs in dissection, hence the name ‘arachnoid’ (thin blue radiating lines in the diagram above)...