In some of its facets human anatomy is closely related to embryology, comparative anatomy and comparative embryology, through common
roots in evolution; for example, much of the human body maintains the ancient segmental pattern that is present in all vertebrates with
basic units being repeated, which is particularly obvious in the vertebral column and in the ribcage, and can be traced from very early embryos.
The human body consists of biological systems, that consist of organs, that consist of tissues, that consist of cells and connective tissue.
Click here for the Levels of Body Organization
What you will be learning in this human anatomy course is the names of locations and structures of the human body.
It will be presented by organ systems. It will require a lot of memorization, visualization, imagination and time.
As a standard point or frame of reference, the human body is described as being in the anatomical position when it is standing erect, facing you, feet together flat on the floor, the arms slightly raised from the sides with the palms facing forward. Here is a list of useful directional terms. Know not only what they mean, but how to correctly use them.
Supine................lying face up
Prone.................lying face down
Anterior (Ventral)............at the front
Posterior (Dorsal)............at the back
Cranial (Cephalic)...............toward the head
Caudal..............toward the tail
Medial..............nearer the midline of the body or a structure
Lateral..............Farther away from the midline of the body or a structure
Ipsilateral...............On the same side of the body or structure
Contralateral..............On the opposite side of the body or structure
Proximal...................Closer to a structure
Distal....................Further away from a structure
Superficial................Closer to the surface
Deep.....................Farther down below the surface
(1:Coronal Section; 2:Transverse (Horizontal) Section; 3:Ventral (Anterior); 4:Dorsal (Posterior);
5:Midsagittal; 6:Proximal; 7:Distal; 8:Superior; 9:Inferior; 10:Medial; 11:Lateral
A different type of cut would be to cut, or section, a specimen in a vertical direction so that you are left with a front piece and a back piece. This type of section is called a coronal section or plane. For example, if you wanted to look at the interior structures of the brain and how their shapes vary as you move from front to back inside the brain, you would need to make a series of coronal sections to follow the changes in the shape of the internal structures.
The third direction that you may wish to cut a specimen, or the entire body, is to cut it into a right piece and a left piece. This type of section is called a sagittal section or plane. Now be careful, I think we all automatically think to cut something equally in half right down the middle, but a sagittal section does not always have to be right down the middle. To cut a specimen right down the middle producing equal right and left halves is called a midsagittal section. To section a secimen into right and left pieces that are not necessarily equal (on off-center cut in the sagittal plane) is to make a parasagittal section.
Remember, we are cutting up a organ or part of the body in order to better visualize the internal structures of that organ or area of the body. You will have to then use your imagination to visualize in your mind how it looks uncut.
So how do we place organs into these cavities and have them stay in place? Even trickier, how to we place an organ that is always moving, say the heart or the lungs or even your intestines, into one of these hollow cavities and keep it in place without firmly attaching it to the inside walls of the cavity since the organ needs to be able to move freely? Let's start with the heart as an example. If you imagine my closed fist as my heart, picture then a balloon right next to my 'fist/heart'. As I push my 'fist/heart' up against the balloon, one side of the balloon is in direct contact with my 'fist/heart' while the opposite side of the balloon is not touching my 'fist/heart'. As I continue to push my 'fist/heart' into the balloon, by 'fist/heart' will become completely surrounded by the balloon.
Yet the other side of the balloon is not touching my 'fist/heart', but is separated from it by the air in the balloon. Assume that the balloon is stick on the outside so that when I push my 'fist/heart' up against it farther and farther, the balloon sticks to my 'fist/heart'. If I hold the other side of the balloon with my other hand, my 'fist/heart' will not fall to the ground since it is stuck to the sticky surface of the balloon (remember, my 'fist/heart' is not suppost to be attached at the wrist). So now all I need to do is place this side of the balloon that is not in contact with the 'fist/heart' up inside my ribs and it will also stick. I've done it. My heart is free to beat and move, yet it won't fall down or wiggle loose since the other side of the balloon is attached to the insides of my ribs. Why this works so well is that it is just one single balloon. But one single balloon with two surfaces. One surface attached to the 'fist/heart' and the other surface attached to the insides of my ribs. This balloon is called the pericardium. Instead of the balloon being filled with air, it is filled with fluid, the pericardial fluid. Now the pericaridium can be named according to what surface you are talking about, the surface stuck to the heart or the surface stuck to the insides of the ribs. This is anatomy, so we give a name to each surface of the pericardium. The part of the pericardium that is stuck to the heart itself is called the visceral pericaridum while the other surface of the pericardium that is attached to the insides of the ribs is called the parietal pericardium. The pericardium has both the visceral portion and the parietal portion, but it is still one continuous balloon, one continuous membrane called the pericardium.
You will very quickly discover in this course that we will be spending a lot of time looking at the different human organs, tissues and cells with a microscope. To look at and learn the surface anatomy of the liver is useful, but to really understand what the liver does, we will need to look directly at liver cells under the microscope. The common term for microscopic anatomy is histology. In fact, you may want to look into some of the very nice internet histology sites to practice learning what the various human cells look like under the microscope. There are also some very nice histology atlases for sale that might be useful to you for a course like this. But check out the internet sites first, since they are free, and any type of atlas is going to be expensive.
In contrast to histology, when you study all the parts of the human body that you can see just with your eyes, with your 'naked eyes' as they say; this is referred to as gross anatomy. So, for example, a gross anatomical structure would just be something you can see without the need for a microscope.
In order to better examine certain organs and tissues, sometimes it is necessary to gently touch these structures. This is referred to as palpation. In order to feel your pulse, you would have to palpate the skin above a blood vessel.
If you listen to the heart, or the lungs inflating and deflating, this is referred to as auscultation. And when the doctor thumps or gently taps on your body, this is referred to as percussion.