Human Anatomy, Color Atlas and Textbook 6th Edition (2017), Basic anatomical Concepts, Terms of Position and Movement, Free Medical Atlases
Terms of Position and Movement
To avoid ambiguity and confusion, anatomical terms of positionand movement are defned according to an internationally accepted convention. This convention defnes the anatomical position as one in which the human body stands erect with the feet together and the face, eyes and palms of the hands directed forwards (Fig. 1.1).
With the subject in the anatomical position, three sets of planes, mutually at right angles, can be defned.
Vertical (or longitudinal) planes are termed either coronal or sagittal. Coronal (or frontal) planes (Fig. 1.2) pass from one side to the other, while sagittal planes (Fig. 1.3) pass from front to back
Fig. 1.1 Anatomical position and the terms used
in anatomical description.
Fig. 1.2 Coronal section through the head
Fig. 1.3 Sagittal section through the trunk. This section lies
to the left of the median sagittal plane
One particular sagittal plane, the median sagittal (midsagittal) plane, lies in the midline and divides the body into right and left halves (Fig. 1.4).
Horizontal (or transverse) planes (Fig. 1.5) transect the body from side to side and front to back.
Sections cut at right angles to the long axis of an organ or parts of the body are also known as transverse. Similarly, longitudinal sections are cut parallel to the long axis.
The terms medial and lateral are used to indicate the position of structures relative to the median sagittal plane. For example, the ring fnger lies lateral to the little fnger but medial to the thumb. The front and back of the body are usually termed the anterior (or ventral) and posterior (or dorsal) surfaces, respectively (Fig. 1.1). Thus one structure is described as anterior to another because it is placed farther forwards. Superior and inferior are terms used to indicate the relativehead/foot positions of structures (Fig. 1.1). Those lying towards the head (or cranial) end of the body are described as superior to others, which are inferior (or caudal). Thus the heart lies superior to the diaphragm; the diaphragm is inferior to the heart. In the limbs, the terms proximal and distal have comparable meanings.
For example, the elbow joint is proximal to the wrist but distal to the shoulder. These terms are also used to indicate the physiological direction of flow in tubes, such as the oesophagus is proximal to the stomach.
The terms superfcial and deep indicate the location of structures in relation to the body surface. Thus the ribs lie superfcial to the lungs but deep to the skin of the chest wall (Fig. 1.5).
Fig. 1.4 Median sagittal section through the trunk
Fig. 1.5 Transverse section through the thorax at the level of the intervertebral disc between the sixth and seventh thoracic vertebrae. Inferior aspect
Movements at joints are also described by specifc terms. From the anatomical position, forward movement of one part in relation to the rest of the body is called flexion. Extension carries the same part posteriorly (Fig. 1.6). However, because in the fetus the developing upper and lower limbs rotate in different directions, the movements of flexion and extension in all joints from the knee downwards occur in opposite directions to the equivalent joints in the upper limb. In abduction, the structure moves away from the median sagittal plane in a lateral direction, whereas adduction moves it towards the midline (Fig. 1.7). For the fngers and toes, the terms abduction and adduction are used in reference to a longitudinal plane passing along the middle fnger or the second toe, respectively. Movement around the longitudinal axis of part of the body is called rotation. In medial (or internal) rotation, the anterior surface of a limb rotates medially, while lateral (or external) rotation turns the anterior surface laterally (Fig. 1.8). Movements that combine flexion, extension, abduction, adduction and medial and lateral rotation (for instance, the ‘windmilling’ action seen at the shoulder joint) are known as circumduction.
Fig. 1.6 Movements of flexion and extension of the shoulder joint
Fig. 1.7 Movements of abduction and adduction. In adduction, flexion of the
shoulder joint allows the limb to be carried anterior to the trunk
Fig. 1.8 Movement of the forearm indicates medial and lateral rotation at the
shoulder joint. The elbow is flexed.
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