Anatomy - An Essential Textbook, Latin Nomenclature (eBook)

1Introduction to Anatomic Systems and Terminology

Anatomy of the human body can be studied by inspection of all the systems that occupy a specific region or by considering the global aspects of a particular system throughout the entire body. The first approach tends to focus on anatomic relationships while the second is better suited to studying physiologic influences. Most systems, however, are conveniently confined to one or two regions, and in this text are discussed in the units devoted to those regions. Some systems, however, (those included in this chapter) are more pervasive throughout the body, and a fundamental understanding of their basic organization is important before undertaking the study of the systems they support.

1.1Structural Design of the Human Body

The most preliminary inspection of the human body reveals that it is structurally divided into a head and neck region, a trunk, and paired upper and lower extremities (limbs). Each is further divided into smaller regions (Fig. 1.1; Table 1.1). These house the structures that make up the functional organ systems that perform the basic bodily functions (Table 1.2). Although the primary organ of a system is often confined to a single anatomic region (e.g., the brain resides in the head), systems extend beyond regional borders, both anatomically and physiologically, to integrate their influences on normal function and growth.

Table 1.1 Regional Subdivisions of the Body

Table 1.2 Functional Subdivisions by Organ Systems

Table 1.3 General Terms of Location and Direction

1.2Terms of Location and Direction, Cardinal Planes, and Axes

—All locational and directional terms used in anatomy, and in medical practice, refer to the human body in the anatomic position, in which the body is upright, arms at the side, with the eyes, palms of the hands, and feet directed forward (Fig. 1.2, Table 1.3).

—Three perpendicular cardinal planes and three axes based on the three spatial coordinates can be drawn through the body (Fig. 1.3).

•The plana sagittalia passes through the body from front to back, dividing it into right and left sides.

•The plana coronalia passes through the body from side to side, dividing it into front (anterior) and back (posterior) parts.

•The plana transversalia (axial, horizontal, cross-sectional planes) divides the body into upper and lower parts. A particular ­transverse section is often given the designation of the corresponding vertebral level, such as T IV, which passes through vertebra thoracica T IV.

•The axis longitudinalis passes along the height of the body in a craniocaudal direction.

•The axis sagittalis passes from the front to the back (or the back to the front) of the body in an anteroposterior direction.

•The axis transversalis (horizontal axis) passes through the body from side to side.