Unsourced material may be challenged and removed. (June 2013). The dorsal nerve cord is one of the embryonic features unique to chordates, along with a notochord, a post-anal tail, an endostyle, and pharyngeal slits. The dorsal nerve cord is a hollow cord dorsal to the notochord.orsal nerve cord is mainly found in subphylum Vertebrata. Dorsal means the back side, as opposed to Ventral which is the front side of an organism. In organisms with Bipedalism dorsal is the back and ventral is the front.
A quad is a rectangular shaped area, especially on a university campus, that's enclosed by buildings. Your college friend might tell you to meet her in the quad after lunch. Quad is an abbreviation, most commonly short for quadrangle, a kind of four-sided courtyard usually defined by a large lawn and surrounded by buildings. Another kind of quad â also an abbreviation â is the large muscle in the top of your thigh, more formally known as a quadriceps muscle. Quadrangle and its nickname, quad, were 1800's Oxford slang, from the Latin root quadri, or four.
In geometry, a square is a regular quadrilateral, which means that it has four equal sides and four equal angles (90-degree angles, or right angles). It can also be defined as a rectangle in which two adjacent sides have equal length. A square with vertices ABCD would be denoted â» {\displaystyle \square } ABCD.