Anatomy Basic

What is anatomy?

Anatomy includes those structures that can be seen grossly (without the aid of magnification) and microscopically (with the aid of magnification). Typically, when used by itself, the term anatomy tends to mean gross or macroscopic anatomy—that is, the study of structures that can be seen without using a microscopic. Microscopic anatomy, also called histology, is the study of cells and tissues using a microscope.

 Observation and visualization are the primary techniques a student should use to learn anatomy. Anatomy is much more than just memorization of lists of names. Although the language of anatomy is important, the network of information needed to visualize the position of physical structures in a patient goes far beyond simple memorization. Knowing the names of the various branches of the external carotid artery is not the same as being able to visualize the course of the lingual artery from its origin in the neck to its termination in the tongue. An understanding of anatomy requires an understanding of the context in which the terminology can be remembered.

HOW CAN GROSS ANATOMY BE STUDIED ?

The term anatomy is derived from the Greek word temnein, meaning “to cut.” Clearly, at its root, the study of anatomy is linked to dissection. Dissection of cadavers by students is now augmented, or even in some cases replaced, by viewing prosected (previously dissected) material and plastic models, or using computer teaching modules and other learning aids.

Anatomy can be studied following either a regional or a systemic approach.

  • With a regional approach, each region of the body is studied separately and all aspects of that region are studied at the same time. For example, if the thorax is to be studied, all of its structures are examined. This includes the vasculature, nerves, bones, muscles, and all other structures and organs located in the region of  the body defined as the thorax. After studying this region, the other regions of the body (i.e., the abdomen, pelvis, lower limb, upper limb, back, head, and neck) are studied in a similar fashion.
  • In contrast, in a systemic approach, each system of  the body is studied and followed throughout the entire body. For example, a study of the cardiovascular system looks at the heart and all of the blood vessels in the body. This approach continues for the whole body until every system, including the nervous, skeletal, muscular, gastrointestinal, respiratory, lymphatic, and reproductive systems, has been studied.

IMPORTANT ANATOMICAL TERMS

The anatomical position

Fig. The anatomical position, planes, and terms of location 

Fig. The anatomical position, planes, and terms of location

The anatomical position is the standard reference position of the body used to describe the location of structures . The body is in the anatomical position when

  • standing upright with feet together,
  • hands by the side, and
  • face looking forward.
  • The mouth is closed and the facial expression is neutral.
  • The rim of bone under the eyes is  in the same horizontal plane as the top of the opening to the ear, and the eyes are open and focused on something in the distance.
  • The palms of the hands face forward with the fingers straight and together and with the pad of the thumb turned 90° to the pads of the fingers.
  • The toes point forward.

Anatomical planes

Three major groups of planes pass through the body in the anatomical position (Fig.).

  • Coronal planes are oriented vertically and divide the body into anterior and posterior parts.
  • Sagittal planes also are oriented vertically, but are at right angles to the coronal planes and divide the body
    into right and left parts. The plane that passes through the center of the body dividing it into equal right and
    left halves is termed the median sagittal plane.
  • Transverse, horizontal, or axial planes divide the body into superior and inferior parts.

Terms to describe location

Anterior (ventral) and posterior (dorsal),  medial and lateral, superior and inferior are three major pairs of terms are used to describe the location of structures relative to the body as a whole or to other structures (Fig.).

  • Anterior (or ventral) and posterior (or dorsal) describe the position of structures relative to the “front” and “back” of the body. For example, the nose is an anterior (ventral) structure, whereas the vertebral column is a posterior (dorsal) structure.
  • Medial and lateral describe the position of structures relative to the median sagittal plane and the sides of  the body. For example, the thumb is lateral to the little finger.
  • Superior and inferior describe structures in reference to the vertical axis of the body. For example, the head is superior to the shoulders.

Proximal and distal, cranial and caudal, and rostral Other terms used to describe positions include proximaland distal, cranial and caudal, and rostral.

  • Proximal and distal are used with reference to being closer to or farther from a structure’s origin, particularly in the limbs. For example, the hand is distal to the elbow joint. These terms are also used to describe the relative positions of branches along the course of linear structures, such as airways, vessels, and nerves. For example, distal branches occur farther away toward the ends, whereas proximal branches occur closer to and toward the origin.
  • Cranial (toward the head) and caudal (toward the tail) are sometimes used instead of superior and inferior, respectively.
  • Rostral is used, particularly in the head, to describe the position of a structure with reference to the nose. For example, the forebrain is rostral to the hindbrain.

Superficial and deep are two other terms used to describe the position of  structures in the body are superficial and deep. These terms are used to describe the relative positions of two structures with respect to the surface of the body. For example, the sternum is superficial to the heart.

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