Wednesday, August 17, 2011

How To Clean an Animal Skeleton

OK, I lied. I'm not posting the exciting conclusion of The Dorsal Forearm today. While I realize Part 2 left you with some massive cliffhangers (Are there really two extensor carpi radialis muscles?) you're just going to have to wait. Because I've once again been sidetracked while cleaning and organizing my home office. My last post on anatomical terminology was inspired by an old illustration; this post, my friends, is inspired by my growing collection of animal bones.

Over the years I've found quite a few partial animal skeletons in my garden, and several friends have been kind enough to give me any ossified treasures found on their property. I have mostly raccoons and possums, plus a few very delicate bird skulls. Having spent so much time learning about, drawing, and teaching classes about the human skeleton, I find it an interesting change of pace to observe these animal structures, in particular those of mammals, to look for features analogous to those of the human skeleton.

Before the bones are added to my collection, though, they need to be cleaned. Over the years I've come up with a pretty good method, and I thought I'd share it here, for any other anatomy lovers out there who want to hang on to a found skull or skeleton.

These are the skeletal remains of a possum I found recently. There is a partial skull, the ilia (which are
part of the pelvis) and two vertebrae. I mislabeled them, though. I think they are probably caudal
vertebrae, which are those in the tail.

So, here is the process I've been using for cleaning animal bones:

1) Have roommates who don't mind finding animal bones soaking in the sink.

2) Let the bones sit out in the sun long enough so any remaining particles of flesh are completely dried out. (It may already be at that stage when you find it!)

3) Gently break off as much of the flesh and fur that you can without damaging the bones.

4) Soak the bones in a bucket of soapy water overnight.

5) Use a soft toothbrush and a little soap to very gently scrub the bones. Then rinse them thoroughly.

6) Soak the bones overnight again, but this time in warm water with about 1/4 cup of bleach added to it.

7) Rinse the bones thoroughly.

8) Lay the bones on a towel and let them dry thoroughly. Letting them sit in the sun will speed up this process.

So there you go. Thanks to Dana for providing the skull above (I think?) Donated bones are welcome to my collection at any time! See you next time for another forearm post.

Monday, August 15, 2011

The Lovely Language of Anatomy and Medicine

The art students to whom I teach anatomy often cringe at the idea of learning structure names. "Why?" they implore, "Why do we need to know the names if all we're doing is drawing them?"

My goal is to show them that in order to discuss the structures that define the human body's shape, we have to have the language for it. We could simply point to different structures and call them "this one" and "this one" and this other one," but it wouldn't mean anything. It wouldn't stick.

And while it's true that my students will very likely forget many names of muscles and bones within a few months after completing my course (you know it's true!) I still believe that the fact that they once knew the names, that they once had to burn the impression of that name in their brain, will mean they'll never forget the structure itself. This may not be the most pleasant analogy, but it's sort of like learning the names of the structures is the actual wound, and remembering the structure and what it looks like is the scar. You need to go a little overboard initially in order to leave a lasting impression.

And aside from all that, I love the practicality of anatomical and medical terms. I mean, they're so descriptive! For example, take the muscle name extensor carpi radialis longus. It tells you just about everything you need to know! It's an extensor (extensor). It extends the wrist (carpi.) It's on the radial side of the forearm (radialis) which means it tends to pull the wrist in that direction as well. And finally, it is the longer of two similar muscles (longus.) By the way, its partner is known as extensor carpi radialis brevis; brevis means short, or brief.

There are many words in anatomical terminology that describe a muscle's function. Here are some examples:

- extensor (extends, or increases the angle of a joint) 
- flexor (flexes, or decreases the angle of a joint) 
- abductor (abducts, or pulls a structure away from the midline of the body) 
- adductor (adducts, or pulls a structure toward the midline of the body)
- tensor (tenses, as in tensor fasciae latae, a muscle that tenses the iliotibial band.)
- arrector (erects something, as in the arrector pili muscles, tiny muscles in the hair follicles which make hairs stand erect and give us goose bumps.)

There are also anatomical terms that describe different areas of the body, such as:

- cranial: having to do with the cranium (as in cranial nerves, cranial arteries, epicranius muscle)
- cervical: having to do with the neck (as in cervical vertebrae, those found in the neck)
- thoracic: having to do with the thorax (as in thoracic vertebrae, those attached to ribs)
- costal: having to do with ribs (as in costal cartilage or intercostal muscles)
- abdominal: having to do with the abdomen (as in the abdominal aorta or the rectus abdominis muscle)
- lumbar: having to do with the lower back (as in lumbar vertebrae, those found in the lower back)
- femoral: having to do with the thigh (as in the rectus femoris muscle, or the femoral artery)
- brachii: having to do with the upper arm (as in the biceps brachii muscles, or the brachialis muscle)
- carpi (wrist; as in extensor carpi ulnaris muscle, or the carpal bones)
- digitorum (fingers or toes; as in extensor digitorum longus muscle in the lower leg, which extends the toes)
- digiti minimi (small finger; as in extensor digiti minimi muscle in the forearm, which extends the little finger)
- pollicis (thumb; as in the many muscles that move the thumb: extensor pollicis longus and brevis, abductor pollicis longus and brevis, flexor pollicis longus and brevis)
- hallicus (big toe; as in extensor hallicus longus, the muscles that extends the big toe)

You'll notice some of the names of aforementioned structures included the term rectus, which brings me to anatomical terms which describe direction and shape:

- rectus: running straight up and down, as in rectus abdominis muscle and rectus femoris muscle.
- oblique: running at an oblique angle, as in external obliques and internal obliques.
- transversus: running transversely or side-to-side, as in the transversus abdominis muscle.
- deltoid: shaped like a Greek delta (triangular) 
- quadratus: four sided, as in the quadratus labii inferioris muscle (four-side muscles inferior to the lower lip) or the pronator quadratus muscle (a four sided muscle deep in the forearm that helps pronate it.)
- serratus: jagged or serrated in shape, such as the serratus anterior muscle.
- trapezius: Muscle on the back that is trapezoid in shape.
- rhomboids: As in rhomboid major and minor, muscles on the back that are shaped like rhombuses. Or is it rhombi?

Some more odd examples of structures named for shape are:

- gastrocnemius: belly shaped
- soleus: fish shaped (and some say this means sandal shaped.)

By now you'll have also noticed many muscle names that describe relativity between two similar muscles:

- longus, brevis (longer and shorter versions of similar muscles, such as extensor pollicis longus and extensor pollicis brevis.)
- maximus, medius, minimus (large medium and small versions of similar muscles, such as gluteus maximus, gluteus medius and gluteus minimus.)
- superficialis, profundus (superficial and deep versions of similar muscles, such as flexor digitorum superficialis and flexor digitorum profundus.)

There are also some pretty cool roots for different internal areas of the body, such as:

- gastro- stomach
- hepato- liver (as in hepatitis, which is inflammation of the liver, or hepatocyte, which is a liver cell.)
- arthro- joint (as in arthritis, which is inflammation of the joints)
- renal: related to the kidney (as in renal artery, or renal calculi, which are kidney stones)
- spondylo- spine (as in spondylitis, which is inflammation of the spine.)
- cardio- heart (as in cardiac muscle)
- pulmo- lungs (as in pulmonary arteries)
- cyto- cells (as in cytology-- the study of cells, or hepatocyte, which is a liver cell.)
- dermo- skin (as in dermatology, the study of skin, or epidermis, which is the outer layer of skin.)

Illustration of gallstones or cholecystolithiasis. Chole = bile; cysto = sac; litho = stones; iasis = process.  Cholecystolithiasis is the process by which stones are formed in the gallbladder, which is basically a sac of bile.

The last example of a beautiful and practical medical term brings us back to the image I found today. It illustrates gallstones, or cholecystolithiasis, whose name can be broken down like this: Chole- means bile; cysto- means sac; litho- means stone; iasis means process. Soooo... cholecystolithiasis is: The process by which stones collect in the gallbladder (which is essentially a sac of bile.) 

Ah, well I've gotten that out of my system. Until next time, anatomy lovers. I promise we will return to Part 3 of the forearm then!