Anatomical Planes

Dissection. Whether that be of a frog, human, mouse, or velociraptor, we've all been presented with the idea of dissecting a specimen for scientific research. Something that you all need to be familiar with, is the various ways that one can separate parts of the body for observation, research, and a better understanding of internal structures and their placement.

A "plane" according to Connie Allen and Valerie Harper in their Anatomy and Physiology laboratory manual is a "flat surface that divides the body or organs, in order to expose internal structures." Click on the following link, to review directional terms, and then look through some introductory information on the different anatomical planes and their titles:
Anatomical Planes Overview
(img:http://www.andrewmoultonmd.com/)

Think about the various anatomical planes you just read about, and compose a list of purposes that the division could serve, one for each of the following: Sagittal (either Mid or Para is fine), Frontal, Transverse, and Oblique. What you'll find is that it is extremely helpful to have these different planes, in order to observe different internal structures and glands of the body.



Just as a brief overview, we'll look at three of the planes present in this picture.
The first to discuss is the plane that is separating the person's front half from his back half. Just thinking about the two parts that are created (front and back), it's fairly easy to remember that this is called a frontal plane. The next one is the plane separating left and right sections of the body. There isn't a cute way to remember this, so just know that it indicates a sagittal plane. Now, the tricky part is that there are two types of sagittal planes; what's nice is that they're easy to distinguish. Mid literally means middle, so midsagittal is almost impossible to forget, because it splits someone right down the middle, into equal right and left halves. Parasagittal, on the other hand, splits the individual into unequal halves. So, midsagittal is a middle slice, while parasagittal incorporates whatever other L/R division is possible. Lastly, the one horizontal plane in this image is the transverse plane. A colleague of mine once said that transverse planes "transform" a human into a centaur which is an adorable way to remember that the cut is a horizontal one, however, transverse planes are not always at the waist, so be careful to remember that.
Note, the other plane that is important to know is the oblique plane. This plane passes through the body at an angle. Conveniently enough, anyone who works out regularly knows that most exercises which are meant to train your obliques involve bending at some angle, so it's intuitive to a handful of people. For the rest of you, you've read it, so remember it. (:

Anatomical Position & Directional Terms

Whether you're studying the anatomy of a human body in a textbook, or you're running a patient through the hospital on a stretcher, the same basic theme applies. Location is everything.
In anatomy, everything has a name, and some of those names are similar, or easily confused when a patient's limbs are sprawled on an operating table.
To describe the location of a limb, there are tons of directional terms to apply to an area of the body, when mentioning it in conversation. Here's a list of the most common terms:

Superior/Inferior
towards the head/towards the foot
*Anterior&Ventral/Posterior&Dorsal
towards the front/towards the back
Proximal/Distal
close to origin or attachment/far from origin or attachment
Medial/Lateral
close to **midline/far from midline
Superficial/Deep
close to surface/far from surface
Ipsilateral/Contralateral
on the same side/on the opposite side
Intermediate: in-between

*Anterior and Posterior: different when describing animals. Refers to head and tail, rather than front and back.
**Midline literally is the area covered if a line was drawn from top to bottom, through the middle of the body.

WHY SO MANY DESCRIPTIVE WORDS?
Put your hand above your head. Your hand is now superior to your shoulder.
Then put your hand down at your side.
...now it's inferior.
Whaaaat?!

Different descriptive words serve different purposes. Depending on the body part/area you're referring to, you may only use one or two words, but those descriptions can't be used to decipher EVERY location.


Something to mention: You usually wouldn't use superior or inferior to describe an appendage for that exact reason stated above. More appropriately, you would say that the hand is distal to the shoulder. That way, regardless of its position, it still holds true.

HOWEVER. to make sure that everyone is on the same page when describing the position of an item on the body, whether it be an appendage, organ, wound, etc, there is a universal "anatomical position" that is used for reference, whenever a location is described.

Anatomical Position...
refers to the view of the body in the image above (http://www.mananatomy.com).
Here's a description: Standing, facing forward, arms down to the side, thumbs away from body, palms up, feet together (approximately below the hips). That's it. This is recognized as a standard reference, so at any point that a textbook or instructor refers to a location on the body, you should ALWAYS assume this position (unless they note otherwise of course).

Now, watch this YouTube clip. It's a phenomenal review of all of this information. Ignore the instructors assignment reviewed at the end, unless you'd like extra credit, then by all means, complete the assignment for a total of ten bonus points.

Let's practice:
Directions: By now, you should be a pro. Answer these questions, and--using the terms from above--place as many directional terms in the blank, in order to make the resulting statements valid. On the top of the page, on the right side, you'll find a pages section with the correct answers (Answer Key includes any reasonable possible answer) Use it to check your work! (:

1) feet are _______ to the torso
2) right arm is _______ to the fingers
3) left hip is _______ to the left leg
4) nose is _______ to the ears
5) eyes are _______ to the elbow
6) left wrist is _______ to the left hand

7) small intestine is _______ to the face

8) left foot is _______ to the right foot

9) neck is _______ to the ears

10) shoulders are _______ to the bellybutton

The Complexity of the Human Body

The human body is unbelievably complex.

This claim, is well understood by just about any researcher who decides to dabble in the subject, by diving into the function of any biological process of the organism. For example, you can take a human body, and break it down to the function of its organ systems. These organ systems include skeletal, digestive, muscular, lymphatic, integumentary, urinary, nervous, cardiovascular, and reproductive systems. Refer to the following images (Illustrations from asweknowit.net):

Each of these organ systems, have their own functions, and are composed of key organs. For our purposes, Take the cardiovascular system. Its main components are the heart, and then the blood vessels (arteries and veins) of the body. Various functions of the cardiovascular system, are to supply oxygen to the cells and tissues of the body, while removing wastes and CO2 from those cells, and providing a source of thermoregulation, through vasoconstriction and vasodilation of the blood vessels.

(Image: American Medical Association)
The organs of the cardiovascular system can be broken down into various tissues: Endothelial tissue, cardiac muscle tissue, and smooth muscle tissue. Each tissue has its own role/function, and all three are required in order for the heart to perform its normal tasks:

These three tissues are composed of individual cells, which contain their own tiny organs, or "organelles" that perform essential tasks for the cells existence. These are functions such as protein synthesis, DNA replication, gas exchange, etc. These tiny organelles are made up of their own monomers, called molecules, which can be broken down even further, into individual atoms.

What's my point?
There's a lot of detail.




There are a lot of tiny pieces, and a lot of whole functions, that all work together to make your body function the way it does. In a way that we commonly refer to in an oh so scientific manner: normal. Not to say that there is one, perfect reference of what is "normal" (we'll get into that later).
Nevertheless, we'll take baby steps. There may be a lot of information about the human body, but let me be neither the first or last to say that it's all some pretty interesting stuff. From the naming of structures, to the variations in placement, we'll start from some basics, and go from there.