Spinal cord blank diagrams, and the Field Museum Patagotitan

Here are some blank diagrams I whipped up for drawing in spinal cord pathways.

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 and conscious proprioception. ALS is anterolateral system, which carries pain, temperature, pressure, and itch. The lateral corticospinal tract carries fibers for voluntary control of major muscle groups. Each pathway differs in terms of where it decussates (crosses the midline, left-to-right and vice versa) and synapses (relays from one neuron to the next). The sensory pathways involve primary, secondary, and tertiary sensory neurons, and the motor pathways involve upper motor neurons (UMNs) and lower motor neurons (LMNs).

This one shows cross-sections of the cord at cervical, thoracic, lumbar, and sacral levels, for drawing ascending and descending pathways and thinking about how patterns of somatotopy come to exist.

Somatotopy is the physical representation of the body in the central nervous system. A common abbreviation scheme is A-T-L for arm-trunk-leg, as shown here for ascending sensory and descending motor pathways.

Finally, this one shows the spinal cord and spinal nerve roots at four adjacent spinal levels, for tracking the specific fates of sensory and motor neurons at each spinal level.

This is particularly useful when working out the consequences of an injury, like the spinal cord hemisection (Brown-Sequard syndrome) shown here in pink. The little human figure only shows the zone in which pain and temperature sensation are lost. There would also be losses of discriminative touch, conscious proprioception, and voluntary motor control on the same side as the injury.

Finally, since we’ve had a bit of a sauropod drought lately, here are a couple of photos of the mounted cast skeleton of Patagotitan in Stanley Field Hall at the Field Museum of Natural History in Chicago.

I gotta say, this mount beats the one at the AMNH in every way, because it’s well lit and you can move all the way around it and even look down on it from above. In fact, in terms of getting to move all the way around it, get well back from it to see the whole thing at once, and even walk directly underneath it (without having to ask permission to hop the fence), it might be the best-mounted sauropod skeleton in the world. The Brachiosaurus outside is also pretty great (evidence), but it loses points because you can’t walk around it on an upstairs balcony. Every other mounted sauropod I know of is either in more cramped surroundings, or you can’t get underneath it, or is less well-lit, or some combination of the above. Am I forgetting any worthy contenders? Feel free to make your case in the comments.

Incidentally, the spinal cord of Patagotitan was something like 120 feet long, and the longest DC-ML primary sensory neurons ran all the way from tail-tip to brainstem before they synapsed, making them among the longest cells in the history of life.

A belated thank-you to Josh Matthews and the rest of the Burpee PaleoFest crew for a fun day at the FMNH back in March. I got home from that trip about 3 days before the pandemic quarantine started, so it’s waaaaay past time for me to blog about how awesome that trip was. Watch this space.