DIRECTIONAL TERMS AND PLANES

1. Know the definitions of the directional terms and planes, and visualize the application of these as shown in Figure 1-13

Throughout this book, descriptive terms will be used when referring to the location of body parts.

Definitions of the terms that follow are illustrated in Figure 1-13 and apply to quadrupeds (four­footed animals).

1. Cranial is a direction toward the head. The lungs are cranial to the intestines (closer to the head).

2. Caudal is a direction toward the tail. The intestines are caudal to the lungs (closer to the tail).

3. Rostral and caudal are terms for direction within the head to mean toward the nose (rostral) or toward the tail (caudal). The cerebrum is rostral to the cerebellum.

4. The median plane is one that passes through the body craniocaudally (from head to tail). It divides the body into equal right and left halves.

5. A sagittal plane is any plane parallel to the median plane and, except for the midsagittal plane (which is another name for the median plane), it would be either to the right or to the left of the median plane.

6. A transverse plane is at right angles to the median plane and divides the body into cranial and caudal parts. A cross-sectional view of the body or part would be made on the transverse plane.

7. A horizontal plane is at right angles to both the median and the transverse planes and would divide the body into dorsal (upper) and ventral (lower) segments.

8. Dorsal pertains to the back or upper surface of an animal. Often used to indicate the position of one structure of the body relative to another (i.e., nearer the back surface of the body). The kidneys are dorsal to the intestines.

9. Ventral pertains to the undersurface of an animal and, as with dorsal, is often used to indicate the position of one structure relative to another. The intestines are ventral to the kidneys.

0. Medial relates to the middle or center; nearer to the median or midsagittal plane. The lungs are medial to the ribs.

11. Lateral is opposite to the meaning of medial (i.e., away from the median plane). The ribs are lateral to the lungs. A lateral radiographic (X-ray) view is one with the animal on its side and the film in the sagittal plane.

.2. Superficial pertains to the surface or to a structure situated near the surface. The skin is superficial to the muscles.

.3. Deep refers to a structure situated at a deeper level in relation to a specific reference point. The femur is deep to the quadriceps muscles.

.4. Proximal, when referring to part of a limb, artery, or nerve, means it is nearest the center of the body or the point of origin. The femur is proximal to the hoof.

1.5. Distal means relatively farther from the center of the body. The hoof is distal to the femur.

.6. Palmar refers to the caudally facing surface of the forelimb distal to the carpus (joint connecting the radius, ulna, and carpals). Dorsal refers to its opposite cranially facing side.

1.7. Plantar refers to the caudally facing surface of the hindlimb distal to the tarsus (also known as the hock; joint connecting the tibia, fibula, and tarsals). Dorsal refers to its opposite (cranial) side.

8. Prone refers to a position in which the dorsal aspect of the body or any extremity is uppermost. A radiograph from this position with the film on the ventral aspect is identified as a dorsal-ventral view.

.9. Supine refers to a position in which the ventral aspect of the body or palmar or plantar aspect of an extremity is uppermost. A radiograph from this position with the film on the dorsal aspect is identified as a ventral-dorsal view.

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