Anatomical Terms

Certain terms are used to describe the location and posi­tion of body parts, imaginary planes and sections of the body, various regions, and body cavities. You should be­come familiar with these terms before your study of anatomy and physiology begins. Use of these terms as­sumes that the body is in the anatomical position: standing erect, with face forward, arms at the sides, and palms and toes directed forward.
Relative Positions of Body Parts
The terms used in figure 1.2 describe the location of one body part in relation to another:
Superior means that a body part is located above another part, or toward the head. Inferior means that a body part is below another part, or toward the feet. The superior vena cava is in the chest, and the inferior vena cava is in the abdomen.
Anterior (ventral) means that a body part is located toward the front. Posterior (dorsal) means that a body part is located toward the back. The windpipe (trachea) is anterior to the esophagus, while the esophagus is posterior to the windpipe.
Medial means that a body part is nearer than another part to an imaginary midline of the body. Lateral means that a body part is farther to the side of the midline. The nose is medial to the eyes; however, the ears are lateral to the eyes.
Proximal means that a body part is closer to the point of attachment or closer to the trunk. Distal means that a body part is farther from the point of attachment or farther from the trunk. The upper arm is proximal to the elbow, and the lower arm is distal to the elbow.
Superficial (external) means that a body part is located near the surface. Deep (internal) means that the body part is located away from the surface. Superficial blood vessels are closer to the skin than those that lie deep in the abdominal cavity.
Central means that a body part is situated at the center of the body or a n organ. Peripheral means that a body part is situated away from the center of the body or an organ. The central nervous system is located along the main axis of the body; the peripheral nervous system is outside the central nervous system.
The terms superior/inferior, anterior/posterior, medial/ lateral, proximal/distal, superficial/deep, and central/ peripheral describe the relative positions of body parts.

 Planes and Sections of the Body To observe internal body parts, it is necessary to section (cut) the body. The body is customarily sectioned by these imaginary planes:

A sagittal (vertical) plane is a lengthwise cut that 

divides the body into right and left portions. A section that passes exactly through the midline is called a midsagittal plane. 

A transverse (horizontal) plane is a cut that divides the body horizontally to give a cross section. A transverse cut divides the body into superior and inferior portions. 

A frontal (coronal) plane is a cut that divides the body lengthwise into anterior and posterior portions. 

The terms longitudinal section and cross section are often ap­plied to body parts that have been removed and cut either lengthwise or straight across, respectively. 

The body or its parts may be sectioned (cut) along certain imaginary planes. A sagittal (vertical) cut divides the body into right and left portions. A transverse (horizontal) cut is a cross section. A frontal (coronal) cut divides the body into anterior and posterior parts. 

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