Our Appendicular System (Carpals, Tarsals & Connections)

I type on keyboards, bake and cook, draw, garden. I am an avid walker, kayaker and practitioner of yoga. I use my hands and feet a lot. Think about everything you do with your hands and feet, including all those little bits like brushing your teeth, and you begin to realize just how much we rely on these appendages. Yet take a look at them – they are so small relative to the rest of our size!

We have eight wrist bones, known as the carpals, consisting of two rows of four bones each. Thankfully, I have not experienced carpal tunnel syndrome (perhaps it is all the yoga that exercises my wrists in multiple directions), but it is not unheard of for intensive computer users to wind up with tingling and discomfort in their wrists.

Extending from our carpals are our metacarpals, five bones that form the palm of the hand and end at the knuckles. As a pre-teen I was a big fan of Archie Comics, and thinking of knuckles makes me think of the term “knucklehead”, which reminds me of Jughead Jones, Archie’s  best buddy.When I was a kid, we used to think of Jughead as a knucklehead, and it was not a flattering term to be called a knucklehead!

Protruding from our metacarpals are our phalanges, more commonly called our fingers. Four of our fingers consist of three phalanges (finger bones) and the stubby thumb has but two. I was curious that our toes are also known as phalanges. It turns out that phalanges are simply the bones in our fingers and toes, and the word comes from the ancient Greek army formation “phalanx” where soldiers would stand side-by-side, aligned just like our fingers and toes.

Down at the bottom of our skeleton we have the tarsals, seven bones that make up our “true ankle” as Marian Diamond refers to them. Turns out our ankle is not the protruding bone on either side of the bottom of our tibia! Five bones form our metatarsal or sole. As you may have noticed, there is a lot of Greek in our anatomy: “meta” as in metacarpal and metatarsal, in this case referring to the bones adjacent to the carpals and tarsals.

Our feet wind down with the phalanges, also called our toes, those piggly wiggly extensions that we take to market with babies. (This little piggy went to market, this little piggy stayed home…)

Of course, our hands and feet are at the very ends of our appendages. Our hands connect to our arms, made up of the humerous at the top (the upper arm) and the forearm at the bottom. Our feet are connected to our legs, made up of the femer at the top (our longest and heaviest bone, the thigh) and the tibia and fibula at the bottom. These bottom sets of our appendages fascinate me because they each consist of two sets of bones.

The forearm is particularly interesting because its two parts, the radius and the ulna, rotate when you turn your arm from hand facing forward to hand  facing backward, with one bone crossing over the other. My younger son is quite familiar with the radius, having broken it twice. (I have no recollection if it was the same forearm or not!)

Finally, there are the two bones of the leg. The tibia is a weight bearing bone and includes the medial malleabus (hammer), one half of the bony parts of the leg that stick out on either side, just above the ankle. It is what I used to refer to as my actual ankle, until Marian Diamond taught me otherwise!

The fibula does not bear any weight and is attached by muscle. The other part of the hammer, the lateral malleabus, is part of the fibula. “Medial” and “lateral” refer to the relative location of the malleabus.

Well, I’ve been at it for awhile this morning, and now it’s time to get my appendages moving to a Saturday morning retreat at school!

@brainbits: Even w/large lecture class, Prof Diamond implores her students– speak out – call out –use your voices to learn by saying. Know it verbally!

@brainbits: I do this http://yogasanctuary.net/ 3-4 times a week, and learning about my anatomy is making a difference in how I move. Very cool!


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