A familiarity with anatomical landmarks, regions, and directional references will make subsequent chapters more understandable. As you encounter new terms, create your own mental maps with the information provided in the accompanying anatomical illustrations.

Anatomical Landmarks

Important anatomical landmarks are presented in Figure 1-6. Anatomical terms are given in boldface type, common names in plain type, and anatomical adjectives in parentheses. Understanding the terms and their origins will help you remember the location of a particular structure as well as its name. For example, the term brachium refers to the arm; in later chapters, we will consider the brachialis muscle and the brachial artery, which are (as their names suggest) in the arm.

Standard anatomical illustrations show the human form in the anatomical position. When the body is in this position, the hands are at the sides with the palms facing forward. Figure 1-6a shows an individual in the anatomical position as seen from the front, and Figure 1-6b from the back. Unless otherwise noted, all descriptions in this text refer to the body in the anatomical position. A person lying down in the anatomical position is said to be supine when face up and prone when face down.

Anatomical Regions

Major regions of the body are listed in Table 1-1 and shown in Figure 1-6. To describe a general area of interest or injury, anatomists and clinicians often need broader terms as well as specific landmarks. Two methods are used, both concerned with mapping the surface of the abdomen and pelvis. Clinicians refer to four abdominopelvic quadrants. The area is divided into four segments by using a pair of imaginary lines that intersect at the umbilicus (navel). This simple method, shown in Figure 1-7a, provides useful references for the description of aches, pains, and injuries. The location can help the physician determine the possible cause; for example, tenderness in the right lower quadrant (RLQ) is a symptom of appendicitis, whereas tenderness in the right upper quadrant (RUQ) may indicate gallbladder or liver problems.

Anatomists like to use more-precise terms to describe the location and orientation of internal organs. They recognize nine abdominopelvic regions (Figure 1-7b). Figure 1-7c shows the relationships among quadrants, regions, and internal organs.

Anatomical Directions

Figure 1-8 and Table 1-2 show the principal directional terms and examples of their use. There are many different terms, and some can be used interchangeably. For example, anterior refers to the front of the body when viewed in the anatomical position; in humans, this term is equivalent to ventral, which refers to the belly. The terms that appear frequently in later chapters have been emphasized. Before you read further, analyze Table 1-2 in detail, and practice using these terms. If you are familiar with the basic vocabulary, the descriptions in future chapters will be easier to follow. When reading anatomical descriptions, you will find it useful to remember that the terms left and right always refer to the left and right sides of the subject, not of the observer.

FIGURE 1-6 Anatomical Landmarks. Anatomical terms are shown in boldface type, common names in plain type, and anatomical adjectives in parentheses.
FIGURE 1-7 Abdominopelvic Quadrants and Regions. (a) Abdominopelvic quadrants divide the area into four sections. These terms, or their abbreviations, are most often used in clinical discussions. (b) Abdominopelvic regions divide the same area into nine sections, providing more-precise regional descriptions. (c) Overlapping quadrants and regions and the relationship between superficial anatomical landmarks and underlying organs.
FIGURE 1-8 Directional References. Important directional terms used in this text are indicated by arrows; definitions and descriptions are included in Table 1-2.
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