Classification Symmetry

Body Direction

Classification of Humans

• Kingdom Animalia• Phylum Chordata• Class Mammalia• Order Primates• Family Hominidae• Genus Homo• Species sapiens

Classification of Dogs

• Kingdom Animalia• Phylum Chordata• Class Mammalia• Order Carnivora• Family Canidae• Genus Canis• Species familiaris

Animal Symmetry

• Asymmetry—no central axis or point • Example: sponge

Animal Symmetry

• Bilateral symmetry—animal has identical right and left images

• Example: crayfish

Animal Symmetry

• Radial symmetry—any plane passing through the center of animal produces identical mirror images

• Example: sea star

Terms of Direction in the Body

• Aboral—end opposite the mouth• Oral—end containing the mouth

Body Direction

• Anterior—head end• Posterior—tail end

Body Direction

• Caudal—toward the tail• Cephalic—toward the head

Body Direction

• Distal—away from the point of attachment of a structure on the body (toes are distal to the knee)

Body Direction

• Proximal—toward the point of attachment of a structure on the body (hip is proximal to the knee)

Body Direction

• Dorsal—back of an animal

Body Direction

• Ventral—belly of an animal

Body Direction

• Inferior—below a point of reference (mouth is inferior to the nose)

Body Direction

• Superior—above a point of reference (the neck is superior to the chest)

Body Direction

• Lateral—away from the plane that divides a bilateral animal into mirror images

Body Direction

• Medial (median)—on or near the plane that divides a bilateral animal into mirror images