Nerves 3 Spinal Nerves
Okay, this is really exciting,so exciting, because we're going to lookat all of our spinal nerves. We're going to look at all ofthese guys right here. And how many of themdo you think we have? Well, we actually have 31pairs of spinal nerves, and I hope you rememberthat our spinal nerves actually travelout of the spinal they travel awayfrom the spinal cord,
and they have to getout of that main hole, in this hole right here, the spinal cord is travelingthrough that hole, and our spinalnerves have to get out of there so that they can go into theperiphery and do their thing. And, to get out,they have to travel between those intervertebral foramina. This is the bodyof my vertebra vertebra
or vertebra depending on, you know, where you wantto place your emphasis and you can imaginethat the hole, the vertebral foramen,is approximately right here, and through thatvertebral foramen is your entire spinal cord. Do you agreethat if I was a rock star I know you think I am but,
every now and then,not so much but if I was, do you agree that Icould actually draw my little crosssection of spinal cord righton my spinal cord? I could cut it in halfand draw it. And then, do you agreethat I actually would have, you know,a dorsal root ganglion
I just made that.It's supposed to be one. There's my dorsal root ganglion, and it's actuallygoing to combine and form a spinal nerve do you follow what I amdoing right here? I'm trying to show you that allthis is is my big column of spinal cord running throughthe vertebral column and then, my actual spinal nerve,
which we are totallycomfortable with. We've seen these,we've gone in, we've gone out, we've taken our spinal nerve, we've named it,we've circled it, we've split it into an anteriorramus and a posterior ramus, that's going to come out throughthese intervertebral foramina. Those were structures that we learned alreadyin the spinal cord.
Nerves 4 Dermatome Man
This is my frienddermatome man. Dermatome man is a map. He's a map of allthe spinal nerves and the parts of spinal nervethat actually innervate skin. And you'll notice that he hasstripes on him, and the stripes representthe different spinal nerves that are sending somesort of sensory fiber or that are carryingsome sort of sensory fiber
in their spinal nerve highwayto this area of skin. Now, I see that I havethe unlabeled version of dermatome man here. I have one dermatome memorizedand that is the belly button. This isthe skinof the belly button, that stripe of dermatome man,the sensory neurons that come from this stripearound your belly button, travel through spinal nerve T10.
Interestingly, the sensoryinformation from your appendix also travels through T10 and,if you think about that, that it hasal significance, because there's a concept calledreferred pain where you actually sometimesperceive visceral pain, like pain in a structure likethe appendix or your small intestineor your heart, you perceive it as pain inone of your dermatomes.
Patients will sometimes come into a 's office and say, oh my god, my belly button. There's something wrong withmy belly button. It really hurts. And the will look atthe belly button and be like, dog pound, you don't haveanything wrong with your belly button. It looks just fine.
But, knowing that the samespinal nerve is carrying fibers from the skin aroundyour belly button, as well as from your appendix, your brain sometimes getsthe messages mixed up and interprets the message asmy belly button hurts even though it's actuallymy appendix hurts. It's a reallyinteresting phenomenon. You will not have to memorizedermatome man.
I recommend throwing a labeledpicture of dermatome man in your external brain, andthat's so that you can actually have it to refer to. On an exam I would definitelyhave a picture of dermatome man for you to refer to if I weregoing to ask you questions about that. A question could be somethinglikeI'm going to have to use the T10 once againbecause I don't know