Intro to Anatomy & Physiology
First, what are Anatomy & Physiology? “Anatomy” comes from Greek, meaning “to cut up”. Anatomy is the study of the structures in the Body. Physiology is the study of how those structures function. They’re technically two different, distinct fields of study but we always talk about them together because form follows function. In other words, the way something works, depends on its form or shape.
For example, studying the shape of bone features (all of the bumps, grooves, rough spots, etc.) will tell you something about how that bone interacts with other bones. All of the macroscopic structures (things that are visible to the naked eye) are thoroughly well understood at this point. Modern Anatomists and Physiologists study the body at the cellular or molecular level.
We always start A&P courses with an introduction to anatomical terminology. It involves memorizing a lot of new terms, most of which are in Latin, Greek, or both. There are 3 basic areas that we have to understand before moving on:
- Regional Terms
- Directional Terms
- Body Planes and Sections
These terms are used to refer to regions or locations in the body. They can be broad or specific. For example, Cephalic refers to the head, Facial refers to the face, and Cranial refers to the bony vault that surrounds the brain. Cephalic would be pretty broad, while Facial and Cranial are more specific.
- Cephalic — the head. You might remember that octopi are known as cephalopods. This terms combines the Latin words for “Head” and “Foot”, which describes an octopus pretty well.
- Facial — the face. You really shouldn’t need a mnemonic device for this one.
- Cranial — the cranium is the vault of bone that surrounds the brain. It’s the top, sides, back, and bottom of the skull. You may be asking, “What’s in the front?” That would be the face.
- Orbital — the area around the eye. You may remember the orbits of planets and satellites are circular (or ellipsoidal) and that the area around the eye is similarly round.
- Mental — the chin. This one actually could be pretty confusing. In class, I always hold my chin and take on a thoughtful expression, to help students remember the mental region.
- Cervical — the neck. This one also confuses a lot of students because most have only heard of the cervix in female anatomy. That cervix is the neck of the uterus.
- Acromial — the shoulders.
- Axillary — the armpits. Temperatures can be taken orally (by mouth), axillary (in the armpit), or rectally.
- Brachial — the arm. To be clear, when an Anatomist talks about the arm, or “arm proper,” they are talking about the upper arm, which starts at the shoulder and ends at the elbow.
- Antecubital — the front of the elbow. We frequently place I.V. needles in the median cubital vein, which is found here.
- Olecranal — the back of the elbow.
- Antebrachial — the forearm. Technically not part of the arm, this region extends from the elbow to the wrist.
- Carpal — the wrist. You’ve probably heard of Carpal-Tunnel Syndrome, which is a repetitive stress injury, which involves tendons that pass through the carpal region.
- Palmar — the palm of the hand.
- Manual — the hand.
- Digital — the fingers, which are also known as “digits”.
- Pectoral — the upper region of the front of the chest, where we find the Pectoralis Major muscle, commonly known as the “Pecs.”
- Mammary — the lower region of the front of the chest, where we find the breast.
- Abdominal — the abdomen or “tummy.” This is a large region, which is usually broken down into 4 Abdominopelvic Quadrants or 9 Abdominopelvic regions. The abdomen contains all of the digestive organs, as well as the spleen and kidneys.
- Pelvic — the “no-no zone.” Here, we find the reproductive organs, the bladder, and the rectum.
- Coxal — the hip.
- Femoral — the thigh. Named for the Femur, which is the longest, strongest bone in the body. This region starts at the hip and ends at the knee.
- Popliteal — the back of the knee.
- Patellar — the front of the knee, where we find the Patella, or “knee cap.”
- Sural — the back of the lower leg, also known as the “calf”
- Crural — the front of the lower leg, also known as the “shin”
- It may be helpful to remember that Crural and Sural start with “C” and “S”. “Calf” and “Shin” also start with “C” and “S”.
- But then you have to remember that the “C” and “S” are reversed.
- Crural = “shin”, Sural = “calf”
- Tarsal — the ankle. The ankle bones are probably a little bit lower than you think. In fact, the “heel” of the foot is actually a tarsal bone.
- Plantar — the bottom of the foot, similar to the palm of the hand.
- Pedal — the foot. Remember that a Podiatrist is a doctor who works on feet. Or remember the cephalopod example at the top of the list.
- Digital (again) — the toes. This one’s easy, fingers and toes are both known as “digits.”
Directional Terms are used to describe the location of a structure, compared to other structures. For instance, I could say “the elbow is closer to the trunk of the body than the wrist is.” But it wouldn’t be science if it wasn’t in Latin, so we say “the elbow is proximal to the wrist.” I guess that’s easier to say, too.
The above example explains the general idea somewhat well, but it’s really not useful. A better example would be: There are 3 bones in most fingers. The one closest to the trunk in the Proximal Phalanx, the one furthest from the trunk is the Distal Phalanx, and the one in the middle is the Middle Phalanx.
- Superior vs Inferior
- Superior means “above.” Think, “Superior quality” or your “superiors” at work.
- Inferior means “below.” Again, think “Inferior quality means lower quality.”
- We could say “The mouth is inferior to the nose.”
- Proximal vs Distal
- Proximal means “closer to the trunk or point of attachment.” Think about similar words, such as “proximity” or “approximate” which both refer to closeness.
- Distal means “further away from the trunk or point of attachment.” Think “distant.”
- Students frequently get these terms confused with superior and inferior. They have very different meanings, but because humans stand upright, we look at the arm and say “of course the elbow is above the wrist.” But technically, it isn’t.
- Just remember that superior and inferior are used in the head, neck, and trunk. Proximal and distal are used in the limbs.
- Anterior vs Posterior
- Anterior means “in front of.” The root, “ante” means before. You could think about “antebellum,” meaning before war or “ante up,” which is where you place a bet in poker before seeing the flop.
- Posterior means “behind.” When I was a kid, my mom used to say, “I’m gonna beat your posterior.” Maybe yours did too.
- Ventral vs Dorsal
- These terms are actually the same as Anterior and Posterior.
- Ventral = Anterior
- Dorsal = Posterior. You may remember that dolphins have a dorsal fin on their back.
- These terms can be used interchangeably, but don’t mix them.
- Saying “Anterior and Posterior” or “Ventral and Dorsal” is okay.
- Saying “Anterior and Dorsal” or “Ventral and Posterior” is not.
- Lateral vs Medial vs Intermediate
- Lateral means “further away from the midline.” This is referring to the imaginary midline that divides the body into two mostly equal parts. The kidneys are lateral to the spine.
- Medial means “closer to the midline.” The eye is medial to the ear.
- Intermediate means “between two structures.” The mouth is intermediate to the cheeks. The bridge of the nose is intermediate to the eyes.
Body planes are imaginary lines that divide the body. What good could that possibly do? Understanding body planes is important when trying to make sense of medical imaging, such as MRI or CT scans (or even X-rays). These imaging devices take a “slice” of the body and if we want to understand what we’re seeing, it’s important to know how the image is oriented.
Sections are actual cuts that we make in the body. These are useful for understanding tubular structures on a microscope slide.
- Sagittal Plane — The sagittal plane divides the body into left and right parts.
- The mid-sagittal plane runs through the imaginary midline of the body and divides it into two mostly equal parts.
- A parasagittal plane divides the body into left and right parts that are not equal.
- Coronal (a.k.a. Frontal) Plane — The coronal plane divides the body into “front” and “back” parts.
- Transverse (a.k.a. Horizontal) Plane — Trans means “across” and -verse means “running.” So, while the other two planes are vertical, this plane runs horizontally across the body, dividing it into upper and lower parts.
- Cross Section — This cut runs across the structure. Think about cutting a hotdog into slices.
- Longitudinal Section — This cut runs the length of the structure. Imagine cutting a hotdog down the middle, into two long pieces. I don’t know why you would do this, but it’s a free country. Maybe to stuff it with cheez?
- Oblique Section — Oblique means “at an angle,” so oblique cuts are cut at an angle and tend to be somewhat oval shaped, when looking at tubules or blood vessels.
Wow. That’s kind of a lot, when you look at it all at once. Take some time, review the terms, and quiz yourself often. Next up, we’ll cover Chemistry. Not… much of it — just enough to understand basic physiology. I promise.