Lesson 1, Topic 1
In Progress

07-Body Regions

April 12, 2021

The body can be divided into two large regions. The axial region is composed of the head, neck, and torso or trunk, whereas the appendicular region is composed of the upper and lower extremities. Body structure and function vary among individuals and also throughout an individual’s life span. For example, atrophy (which is a decrease in size) may occur when an organ is not used.


Abdominopelvic regions
Another and perhaps more precise way to divide the abdominopelvic cavity is shown in Figure 1-7. Here, the abdominopelvic cavity is subdivided into nine abdominopelvic regions defined as follows:

1. Upper abdominopelvic regions—the right hypochondriac region, left hypochondriac region, and the epigastric region lie above an imaginary line across the abdomen at the level of the ninth rib cartilages.
2. Middle abdominopelvic regions—the right lumbar region, left lumbar region, and the umbilical region lie below an imaginary line across the abdomen at the level of the ninth rib cartilages and above an imaginary line across the abdomen at the top of the hip bones.
3. Lower abdominopelvic regions—the right iliac region, left iliac region (also called inguinal regions), and the hypogastric region lie below an imaginary line across the abdomen at the level of the top of the hip bones.

Some of the organs in the largest body cavities are visible in Figure 1-8 and are listed in Table 1-1. Find each body cavity in a model of the human body if you have access to one. Try 11to identify the organs in each cavity, and try to visualize their locations in your own body. Study Figure 1-5 and Figure 1-8 and explore the layers of the Clear View of the Human Body insert located in this book after.

Body regions
To recognize an object, you usually first notice its overall structure and form. For example, a car is recognized as a car before the specific details of its tires, grill, or wheel covers are noted. Recognition of the human form also occurs as you first identify overall shape and basic outline. However, for more specific identification to occur, details of size, shape, and appearance of individual body areas must be described. Individuals differ in overall appearance because specific body areas such as the face or torso have unique identifying characteristics. Detailed descriptions of the human form require that specific regions be identified and appropriate terms be used to describe them.

The ability to identify and correctly describe specific body areas is particularly important in the health sciences. For a patient to complain of pain in the head is not as specific, and therefore not as useful to a health professional, as a more specific and localized description would be. Saying that the pain is facial provides additional information and helps to more specifically identify the area of pain. By using correct anatomical terms such as forehead, cheek, or chin to describe the area of pain, attention can be focused even more quickly on the specific anatomical area that may need attention.

Familiarize yourself with the more common terms used to describe specific body regions identified in Figure 1-9 and listed in Table 1-2. Explore the Clear View of the Human Body insert located in this book after p. 8 to find the major body regions.

The body as a whole can be subdivided into two major portions or components: axial and appendicular. The axial portion of the body consists of the head, neck, and torso or trunk. The appendicular portion consists of the upper and lower extremities (or limbs). Each major axial and appendicular area is subdivided as shown in Figure 1-9. Note, for example, that the torso is composed of thoracic, abdominal, and pelvic areas, and the upper extremity is divided into arm, forearm, wrist, and hand components.

Although most terms used to describe gross body regions are well understood, misuse is common. The word leg is a good example: it refers to the area of the lower extremity between the knee and ankle and not to the entire lower extremity.
The structure of each person’s body is unique. Even identical twins have some variations in the size, shape, and texture of various tissues and organs.

The structure of the body also changes in many ways and at varying rates during a lifetime. Before young adulthood, the body develops and grows. After young adulthood, the body gradually undergoes changes related to aging. For example, with the reduced activity of the body as one advances through older adulthood, body organs and tissues decrease in size and therefore change in their functions. A degenerative process that results from disuse is called atrophy. In many cases, atrophy can be reversed with therapy. Some tissues simply lose their elasticity or ability to regenerate as we get older. Nearly every chapter of this book refers to a few of the changes that occur through the life cycle.

Before moving ahead, we pause to consider what seems like an overwhelming number of scientific terms introduced in the preceding sections. It is important to know that such terminology is a “new language” that you must learn as you continue your studies. Now is a good time to review the introduction to this new language in Appendix B at evolve.elsevier​.com. Then, in upcoming chapters, make it a habit to read through the new terms in the chapter word lists—pausing to pronounce each term out loud and glance at its word parts—before starting your reading. Such a strategy will help you slowly and comfortably build a mastery of scientific language.