The Human Body

The Human Body is a complex organization of cells. These cells are organized into sheets of tissue, the tissue is organized into structures called organs, the organs are organized into organ systems and those organ systems are organized into an organism which we call "The Human Body." Each system in the body serves to assist other systems for the good of the organism. An understanding of the body's organ systems is important, if the EMT is to understand what can go wrong, should one of the systems be damaged or unable to function. In this section we will go through the human body, discussing each system in as much detail as we feel is necessary in order to adequately familiarize you with the function of that system, and how it interrelates with other systems. For the purposes of this course, we will discuss the Skeletal System, the Muscular System (referred to as the Musculoskeletal System, when it's interaction with the skeletal system is discussed,) the Respiratory System, the Circulatory System (sometimes referred to as the Cardiovascular System, when it does not include the Lymphatic sub-system,) the Nervous System, the Integumentary System, the Endocrine system, the Digestive System, the Urinary System, and the Reproductive System. Before we begin our discussion of the various systems of the human body, we need to set some ground work regarding terminology.

The Human Body

Basic Terminology

This illustration depicts a position called the "Anatomical Position." We will refer to it many times during the course of this website dissertation. It represents the basis from which all directions and directional concepts will be developed. In addition to the "obvious," please note, that the subject is standing with his arms at his side and the palms of the hands are facing forward.

There are five surfaces (sometimes referred to as "planes" or "aspects") that need definition. The anterior surface of this subject's body is that surface that can be seen (the front,) and the posterior surface is that surface that can not be seen (the back.) The midline is kind of self-explanatory. It is a line drawn down the anterior (or posterior) aspect dividing the body into left and right halves. There are four other such lines, (not illustrated here). Two of which, are referred to as midclavicular (one left, one right,) which originate at the approximate midpoint of a bone called the clavicle (more about bones, later.) and define planes which are parallel to the midline and divide each half in half again. The other two lines, referred to as midaxillary (again, left and right,) originate under the arms, an area referred to as the axilla. They divide each half (as defined by the midline) into quarters.

There are eight pairs of directional concepts to define. Left and right, always refer to the patient's left or right. To the left or right of the midline, moving away from it or back toward it, is a concept that defines lateral or medial. Lateral being farther from the midline, medial being closer to the midline. Superior is closer to the head, than inferior which is closer to the feet (simply stated higher or lower.) Proximal and distal refer to directions or relationships between different structures or aspects of the extremities (arms and legs.) For example the elbow is proximal to the wrist, and the elbow is distal to the shoulder. Superficial and deep are "measurements" of depth from the surface of the skin, and don't need much explanation. Ventral and dorsal refer to the anterior and posterior aspects of the torso (generally used when the patient is not in the "anatomical position," or the "patient" is not customarily thought of as one who walks upright.) Our "trick" for remembering which is which (ventral or dorsal,) is to picture a shark gliding through the water with it's "dorsal" fin exposed (that's the fin that is on the sharks "back.") These two terms are also useful to describe aspects of the feet and hands, but more specifically the ventral (inferior) aspect of the foot is referred to as plantar and the ventral (anterior) aspect of the hand as palmar.) Bilateral and unilateral are used to describe structures or occurrences in the body. Eyes, for example are bilateral (one on either side of the midline,) whereas some organs are unilateral (the spleen.) A patient might be a bilateral amputee (having lost both legs,) or might be experiencing unilateral paralysis secondary to a stroke. Contralateral and ipsilateral refer to the same side or different sides. A patient might have pain that originates in an area just superior to the left ear, travels over the superior aspect of the skull and travels down the contralateral aspect of the upper torso. (pain starts just over the left ear, goes over the top of the head and down the right side of the body,) or may have sustained superficial burns to the medial aspect of the right upper extremity, with superficial and deep burns to lateral aspect of the ipsilateral lower extremity (superficial burns to the inside of the right arm and superficial and full thickness burns to the outside of the right leg.)

That's medical terminology, cool, Huh?

To help "locate" injury or pain in the abdomen, it has been divided into quadrants. The quadrants are defined by the intersection of the midline and a horizontal line drawn through the umbilicus, dividing the abdomen into right upper (RUQ,) right lower (RLQ,) left upper (LUQ,) and left lower (LLQ) quadrants. If a joint is designed to move, it can rotate, flex or extent, abduct or adduct. Rotation is a simple concept, but if it's one that you don't understand, shake you head "NO." You just rotated the skull at the Atlas (C-1) around the Axis (C-2.) In general, flexion and abduction are movements away from the anatomical position, for example, bending the arm forward or leg backwards, or the trunk forward (away from the anatomical position) is flexion, and moving the legs or arms to the side (away from the anatomical position) is abduction. Extension and adduction are movements back toward the anatomical position. Two exceptions are the head and feet. From the anatomical position, moving the foot upward is flexion (extension would be the opposite, "pointing your toes") and moving the top of the head posteriorly would be extension (you've all taken CPR classes, and should understand the concept of "hyperextension.")

You need some terminology for the different positions in which patients may be found or transported. Recumbent is lying down and erect is standing up. Prone is lying face down, supine is face up, and lateral is lying on the side. A patient found "left lateral recumbent" is lying down on the left side. Fowler's position is sitting with the knees slightly bent. Some texts further break this position down into low Fowler's and high Fowler's depending on the amount of flexion added to the upper torso. Trendelenburg's position is where the head is lower than the body and there is no flexion in the torso. The shock position is where the feet are raised a few inches (according to local protocol) and the torso is slightly flexed at the hips (sometimes referred to as modified Trendelenburg's position.) If the patient has a hip injury, this modified Trendelenburg's position should not be used, for obvious reasons. Transporting a patient in the prone position is, from our experience, dangerous. The patient's airway CAN NOT be maintained when a patient is transported while pronated, but it's important to know because the patient may be found lying prone. The recovery position is left lateral recumbent (or "right" with sustained injury to the left side) with some flexion added to the extremities.

Decortication and decerebration are rather advanced concepts of positioning but you may find a patient in either and we feel that given the proper information, you should be able to recognize them. Both are indications of profound brain damage, one being worse than the other. At the "on-set" of this profound brain damage, the patient will decorticate (upper extremities flex toward the midline and lower extremities adduct. Both upper and lower extremities become rigid,) as the damage continues the patient begins to decerebrate (extremities flail away from the midline and abduct, and rigidity subsides.) In the presence of either of these two positions, coupled with unresponsiveness, look for indications of head injury or rising intracranial pressure.

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