Descriptive Terms

A. Aspects of the Body and Cardinal DirectionsNote: Regardless of how the specimen is viewed by the observer, the aspects of the body and anatomical directions always refer to the normal horizontal position of the animal (erect position in man).1. Cephalic/cranial/anterior (superior in human anatomy) – the head end of the animal; the

direction towards or beyond the head.2. Caudal/posterior (inferior in human anatomy) – the tail end of the animal; the direction

towards or beyond the tail3. Dorsal (posterior in human anatomy) – the back or upper side of the animal; the direction

towards or beyond the back4. Ventral (anterior in human anatomy) – the underside of the animal; direction towards or

beyond the underside5. Lateral (same as in human anatomy) – the sides of the animal (sinistral, the left side; dextral,

the right side); the direction towards or beyond the side6. Median (same as in human anatomy) – the middle; the direction towards the middle

B. Oblique DirectionsThe oblique directions which are expressed by hyphenated terms, are used to indicate directions between two or three of the cardinal directions. Two or three of the cardinal directions are combined to form these hyphenated terms wherein the terminal letters of the word preceding the hyphen are substituted with the letter “o.” For example, from a particular structure or point of reference, anterodorsal would refer to the direction between the anterior and dorsal directions; postero-dorso-lateral would be the direction between the posterior, dorsal and lateral directions

C. Planes and AxesOther than the cardinal and oblique directions are the planes and axes which may serve as references for structures of animal anatomy.1. Median Plane or section – a vertical longitudinal plane extending from the imaginary mid-

dorsal line to the imaginary mid-ventral line passing through the longitudinal axis2. Sagittal plane or section – any vertical longitudinal plane through the body. If it coincides

with the median plane, it is called the medial sagittal plane. Any plane or section parallel with but lateral to the median sagittal plane is called parasagittal.

3. Horizontal plane or section (frontal in human anatomy) – any plane at right angles to the median plane and parallel to the dorsal and ventral surfaces of the body

4. Transverse or cross plane or section – any plane that cuts vertically across the body at right angles to the sagittal and horizontal planes

5. Longitudinal or antero-posterior axis – an imaginary line along the middle of the median sagittal plane extending from the anterior to posterior ends of the body

6. Sagittal or dorso-ventral axis – an imaginary line along the middle of the median sagittal plane extending from the dorsal to ventral surfaces of the body

7. Transverse or medio-lateral axis – an imaginary line at right angles to the longitudinal and sagittal axes extending from side to side of the body

D. Other Descriptive Terms1. Proximal – near the main mass of the body; near a major point of reference2. Distal – away from the main mass of the body; away from a major point of reference3. Peripheral – near the surface of the body or organ4. Central – near or at the middle of the body or organ

5. Superficial or ectal – on the outer surface of the body or organ6. Deep or ental – inner or below the surface of the body or organ7. Superior – above8. Inferior – below9. Preaxial – toward the inner or near the axis or median plane10. Postaxial – away or far from the axis or median plane of the body

The Frog as a Representative Animal

1. The frog’s anatomy shows numerous similarities in basic structure and organization with those of other vertebrates, including man

2. The frog’s size is convenient enough for easy handling during dissection. Its small size requires less chemical preservative and space for storage

3. Since the frog’s physiology is well studied, the frog may be used in simple experiments to easily demonstrate various fundamental physiological principles

4. A cheap and steady supply of laboratory specimens can easily be obtained because of the abundance and availability of the frog throughout the year.

5. A frog’s life cycle can be readily observed and demonstrated under either natural or laboratory conditions