Page 111.4 The Language of Anatomy and PhysiologyClinicians and researchers in anatomy and physiology require a precise language to ensure that they are all discussing the same features and functions. A technical terminology has been developed that describes body position, direction, regions, and body cavities. These technical terms are different from those used in everyday conversation, because the more conversational terms often do not accurately describe location and position or identify structures. For example, the term arm in everyday conversation refers to the entire upper limb, but in anatomy the specificportions of the upper limb are named, and the term arm or brachium refers only to that part of the upper limb between the shoulder and the elbow.Most anatomic and physiologic terms are derived from Greek or Latin, and we frequently provide word origins, pronunciations, and definitions of terms where appropriate throughout this text. We've used Stedman's Medical Dictionary (which defines all medical terms) and Terminologia Anatomica (which lists and categorizes the modern, proper anatomic terms) as references.1.4a Anatomic PositionLEARNING OBJECTIVE1. Describe the anatomic position and its importance in the study of anatomy.Descriptions of any body region or part require a common initial point of reference. Note that terms such as “anterior” or “posterior” can be relative terms. For example, when a person is standing it would be accurate to say “the heart is superior to the stomach,” yet if that person is lying down in a supine position, this statement would seem not to be true. For accuracy and clarity, anatomists and physiologists describe these parts based on the premise that the body is in what is termed the anatomic position, which is then the point of common reference. An individual in the anatomic position stands upright with the feet parallel and flat on the floor, the upper limbs are at the sides of the body, and the palms face anteriorly (toward the front); the head is level, and the eyes look forward toward the observer (figure 1.4). All of the anatomic anddirectional terms used in this book refer to the body in anatomic position.Figure 1.4Anatomic Position and Body Planes.(a) In the anatomic position, the body is upright, and the forearms are positioned so the palms are facing anteriorly. A plane is an imaginary surface that slices the body into specific sections. The three major anatomic planes of reference are the (b) coronal, (c) transverse, and (d) midsagittal planes. APR Module 1: Body Orientation: Planes of SectionLEARNING STRATEGYBreaking a word into smaller parts can help you understand and remember its meaning. In this book, we provide word derivations for new terms following their pronunciations. For example, inthe case of histology, the study of tissues, we give (histos = web, tissue, logos = study).Many biological terms share some of the same prefixes, suffixes, and word roots, so learning the meanings of these common terms can help you figure out the meanings of unfamiliar terms. A review of prefixes, suffixes, and word roots also appears on the inside of the back cover of this book.Page 121.4b Sections and PlanesLEARNING OBJECTIVE2. Describe the anatomic sections and planes through the body.Anatomists and physiologists refer to real or imaginary “slices” of the body, called sections or planes, to examine the internal anatomy and describe the position of one body part relative to another. The term section implies an actual cut or slice to expose the internal anatomy, while the word plane implies an imaginary flat surface passing through the body. The three major anatomic planes are the coronal, transverse, and midsagittal planes (figure 1.4).A coronal (kōr′ō-năl; korone = crown) plane, also called a frontal plane, is a vertical plane that divides the body or organ into anterior (front) and posterior (back) parts. When a coronal plane is taken through the trunk, the anterior portion contains the chest and the posterior portion contains the back and buttocks.A transverse plane, also called a horizontal plane or cross-sectional plane, divides the body or organ into superior (top) and inferior (bottom) parts. If a transverse plane is taken through the middle of the trunk, the superior portion contains the chest and the inferior portion contains the abdomen.A midsagittal (mid-saj′ĭ-tăl; sagitta = arrow) plane, or median plane, is a vertical plane and divides the body or organ into left and right halves. A midsagittal plane through the head will split it into a left half and a right half (each containing one eye, one ear, and half of the nose and mouth). A plane that is parallel to the midsagittal plane, but either to the left or right of the midsagittal plane, is termed a sagittal plane. A sagittal plane divides a structure into left and right portions that may not be equal. Although there is only one midsagittal plane, an infinite number of sagittal planes are possible.In addition to these major planes, there are numerous minor planes called oblique (ob-lēk′) planes that pass through a structure at an angle.Interpreting body sections has become increasingly important for health-care professionals. Technical advances in medical imaging have produced sectional images of internal body structures (figure 1.4b). To determine the shape of any object within a section, we must be able to reconstruct its three-dimensional shape by observing many continuous sections.Sectioning the body or an organ along different planes often results in very different views of that organ or region. For example, different sections through the abdominal cavity exhibit multiple profiles of the long, twisted tube that is the small intestine. These sections may appear as circles, ovals, a figure eight, or maybe a long tube with parallel sides, depending on where the section was taken (figure 1.5). Being able to convert and interpret two-dimensional images into three-dimensional structures is especially important when comparing and understanding histologic and gross anatomic views of the same organ.Figure 1.5Three-dimensional Reconstruction from Planes of Section.Serial sections through an object are used to reconstruct its three-dimensional structure, as in these sections of the small intestine. Often a single section, such as the plane at the lower part of this figure, misrepresents the complete structure of the object.WHAT DID YOU LEARN?What type of