CHAPTER 1 Introduction to the Human body 1.15 Why are the palms given an orientation that seems unnatural? During early embryonic development, the palms are supine(facing forward or upward). Later, an axial rota- tion of each forearm puts the palms in a prone position(facing backward or downward). Thus, the anatom- ical position orients the upper extremities as in early development Objective G To identify the planes of reference used to locate and describe structures within the body A set of three planes (imaginary flat surfaces) passing through the body is frequently used to ey depict structural arrangement. The three planes are termed the midsagittal, coronal, and trans verse p Coronal plane Figure 1.13 For descriptive purposes, the Figure 1.14 Planes of reference through the body. anatomical position provides a standard reference framework for the body 1.16 Distinguish between the principal body planes Three cardinal planes are use to divide and describe the anatomy of the body. The sagittal plane divides the body into right and left portions, the coronal(frontal) plane divides the body into anterior and pos terior portions, and the transverse(horizontal) plane divides the body into superior and inferior por tions. The sagittal plane that divides the body into right and left halves is known as the midsagittal median) plane(see fig. 1. 14) 1. 17 With reference to the planes of the body, discuss the advantage of computed tomography (CT or CAt scans and magnetic resonance images(MRIs)over conventional x-rays Conventional radiographs or x-rays are of limited clinical value because they are taken on a vertical plane thus, images of various structures are often superimposed. One major advantage of CT scans and MRis is that they can display images along transverse or sagittal planes. These images are similar to those that could otherwise be obtained only in actual sections through the body1.15 Why are the palms given an orientation that seems unnatural? During early embryonic development, the palms are supine (facing forward or upward). Later, an axial rota￾tion of each forearm puts the palms in a prone position (facing backward or downward). Thus, the anatom￾ical position orients the upper extremities as in early development. Objective G To identify the planes of reference used to locate and describe structures within the body. A set of three planes (imaginary flat surfaces) passing through the body is frequently used to depict structural arrangement. The three planes are termed the midsagittal, coronal, and trans￾verse planes. 8 CHAPTER 1 Introduction to the Human Body Survey Figure 1.13 For descriptive purposes, the anatomical position provides a standard reference framework for the body. Figure 1.14 Planes of reference through the body. 1.16 Distinguish between the principal body planes. Three cardinal planes are use to divide and describe the anatomy of the body. The sagittal plane divides the body into right and left portions, the coronal (frontal) plane divides the body into anterior and pos￾terior portions, and the transverse (horizontal) plane divides the body into superior and inferior por￾tions. The sagittal plane that divides the body into right and left halves is known as the midsagittal (median) plane (see fig. 1.14). 1.17 With reference to the planes of the body, discuss the advantage of computed tomography (CT or CAT) scans and magnetic resonance images (MRIs) over conventional x-rays. Conventional radiographs or x-rays are of limited clinical value because they are taken on a vertical plane; thus, images of various structures are often superimposed. One major advantage of CT scans and MRIs is that they can display images along transverse or sagittal planes. These images are similar to those that could otherwise be obtained only in actual sections through the body