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Animals typically have one end with a head and mouth, with the opposite end often having the anus and tail. The head end is the cranial end; the tail end is the caudal end. Within the head itself, rostral refers to the direction toward the end of the nose, and caudal is still used to refer to the tail direction.
The surface or side of the body normally oriented upwards, away from the pull of gravity, is the dorsal side; the opposite side, typically the one closest to the ground when walking on all legs, swimming or flying, is the ventral side. For example: in vertebrates, the spine or nerve chord is located on the dorsal side of the organism. A cow's udder is on the ventral side. A dolphin's dorsal fin is, unsurprisingly, on the dorsal side.
The right and left side (sometimes in Latin: dexter - right, and sinister - left) are given as viewed from the animal that is described.
In human anatomy, the body and its parts are always described using the assumption that the body is in anatomical position, i.e. standing upright.
Portions of the body which are closer to the head end are "superior" ("upper"); those which are farther away are "inferior" ("lower") -- superior corresponds to cranial, and inferior to caudal. Objects near the front are "anterior"; those near the rear are "posterior" -- these correspond respectively to "ventral" and "dorsal". On the limbs, an object closer to the main body is "proximal"; an object farther away is "distal".
The terms "anterior" and "posterior" should not be used when referring to most animals however, and are particularly incorrect for quadrupeds.
Three basic reference planes are used in zoological anatomy. The sagittal plane divides the body into left and right halves. A coronal plane divides the body into dorsal and ventral halves. A transverse plane divides the body into cranial and caudal halves.
Sometimes the orientation of certain planes need to be distinguished, for instance in medical imaging techniques such as CT scans, MRI scans or PET scans. One imagines a human in anatomical position (standing, arms hanging down with palms to the front) and an X-Y-Z coordinate systemCartesian means relating to the French mathematician and philosopher Descartes, who, among other things, worked to merge algebra and Euclidean geometry. This work was influential to the development of analytic geometry, calculus, and cartography. The idea with the X-Y plane parallel to the ground, the X-axis going from left to right, the Y-axis passing from front to back, and the Z-axis going up and down.
Structures near the midline are called medial and those near the sides of animals are called lateral. Therefore, medial structures are closer to the midsagittal plane, lateral structures are further from the midsagittal plane. Structures in the midline of the body are median. For example, your cheeks are lateral to your nose and the tip of the nose is in the median line.
Structures that are close to the center of the body are proximal or central, while ones far removed are distal or peripheral. For example, the hands are at the distal end of the arms, while the shoulders are at the proximal ends. These terms can also be used relatively to organs, for example the proximal end of the urethraIn anatomy, the urethra is a tube which connects the urinary bladder to the outside of the body. The urethra has an excretory function in both sexes, to pass urine to the outside, and also a reproductive function in the male, as a passage for sperm. The e is attached to the bladderIn the anatomy of mammals, the urinary bladder is the organ that collects urine excreted by the kidneys prior to disposal by urination. Urine enters the bladder via the ureters and exits via the urethra. Anatomy The urinary bladder is a hollow, muscular a.
Structures on or closer to the body´s surface are superficial (or external) and those further inside are profound or deep (or internal).
When speaking of inner organs, visceral means close to or attached to the organ, while parietal is more distant. For example, the visceral pleuraIn anatomy, the pleural cavity is the potential space between the lungs and the chest wall. It has virtually nothing in it in the normal non-diseased state, except a small amount of pleural fluid . The cavity is lined by specialized epithelium called pleu is attached to the lung and the parietal pleura is attached to the chest wall.
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