dorsals

Dorsal is an anatomical term meaning related to the back or upper side of an organism. The word comes from Latin dorsum, “back.” In humans and other vertebrates, the dorsal surface is the back side, opposite the ventral (belly) surface. The term is used as an adjective (dorsal fin, dorsal aspect) and as a noun in some contexts, especially in zoology where dorsals may refer to dorsal fins or other dorsal structures.

In general anatomy, dorsal describes location or orientation on the back or upper side. For example, the dorsal aspect of the hand refers to the back of the hand, while the dorsal surface of the trunk encompasses the back muscles and spine. The term contrasts with ventral, lateral, and medial when describing where structures lie.

In fishes and many marine animals, dorsals most commonly refer to dorsal fins—fins located along the midline on the animal’s back. They may be single or multiple; many bony fishes have two distinct dorsal fins, one spinous and one soft-rayed, which can be separate or fused. Dorsal fins contribute to stability and maneuvering and may bear spines for protection.

In development and comparative anatomy, dorsal refers to the back-side of the embryo or body plan. The dorsal side houses structures such as the dorsal nerve cord in chordates and the posterior distribution of certain tissues. Dorsal-ventral patterning is a fundamental axis of embryology, shaping organ development along the back-to-front axis.

Related terms include ventral (belly side) and dorsal fin and dorsal structures in various taxa.