You may have heard the expression used to explain the three rules of real estate: location, location, location. The same expression applies to the specific terms doctors use to describe one body part relative to another. It's all about the location. For example, if I'm facing a patient and examining her left shoulder, I could, logically enough, refer to it as her left shoulder or, I might describe it as a problem on her right side since, when I'm facing the patient, her left is my right. Right? Fortunately, medical terminology has evolved to include a standard system of descriptors that, at its best, leaves no chance for this sort of misunderstanding. That's great for doctors, but what about the non-medical person who's trying to understand the technical terms being used to explain a diagnosis or treatment? Read on to learn what your doctor is really saying about which end is up, literally. When it comes to deciphering your doctor's language, you'll never be lost again. The Starting Point: The Anatomic Position Without a starting point, it's hard to imagine how any two people would describe the same spot on the body in the same way. For doctors, home base when referring to various locations on the body is the "anatomic position" where the patient is standing, arms at the side, palms facing outward toward the observer. This helps avoid confusion when referring to the front, back or side of the body.
So a point close to the center of the body is called "medial" and one that is away from the center is called "lateral." For example, the medial parts of the arm and forearm are on the same side as the little finger (pinky). And the lateral arm and forearm are on the same side as the thumb. Similarly, anything "above" (closer to the head) is "superior" while anything below (closer to the feet) is "inferior." A pain in the stomach or upper abdomen is superior to the navel but inferior to the ribs. Less common terms for superior and inferior are "cephalad"—above or toward the head— and "caudal"—under or toward the feet. Different Parts, Different Terms Different parts of the body use different language to describe location. For example, the abdomen is divided into four equal sections, called "quadrants." They are named according to the person's anatomic position. So, the right upper quadrant is the right side of the abdomen above the navel on the same side as the right arm. Pain that arises from an inflamed appendix is usually in the right lower quadrant while left lower quadrant pain is more typical of diverticulitis. The lungs, meanwhile, are commonly described in "fields." Your doctor may hear normal air movement in the upper lung fields through the stethoscope but congestion or decreased sounds in the lower lung fields (or the very bottom of the lungs). While the abdomen has quadrants and the lungs have fields, the fingers are numbered starting with the thumb as number one, the index finger as number two, and so on. The toes are similarly numbered. The front of the body is called "anterior" or "ventral," while "posterior" or "dorsal" refers to the back. So, a physician might say there is a laceration (cut) on the dorsal aspect of the hand. Remember, the anatomic position means a person is facing an observer with palms up, so the dorsal aspect is the back of the hand not the palm. The posterior cerebral artery provides blood to the back of the brain. The middle of the back or the abdomen itself is usually called (oddly enough!) the "middle" but often the term "midline" or "mid" is used instead. So, a scar might be called midline or pain might be described as mid-epigastic (meaning in the middle abdomen, overlying the stomach). The parts of the body furthest away from the middle are "lateral." For example, doctors might call the region just under the armpit the lateral thorax while the outside part of the thigh would be called the lateral thigh. By convention, the right and left sides of the body are described from the patient’s perspective. So in the example I used in the introduction, when I'm facing a patient and examining the left shoulder, it doesn't matter that her left is my right. I still refer to it as the left shoulder. Getting around in an unfamiliar place is tough. When that place is your own body and you aren't feeling well, it can be confusing and intimidating. Don't let the unfamiliar terms get you lost – just learn a bit more about what your doctor is saying, and you'll be on the right track. Robert H. Shmerling, M.D. is associate physician at Beth Israel Deaconess Medical Center and associate professor at Harvard Medical School. He has been a practicing rheumatologist for over 20 years at Beth Israel Deaconess Medical Center. He is an active teacher in the Internal Medicine Residency Program, serving as the Robinson Firm Chief. He is also a teacher in the Rheumatology Fellowship Program.
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