Deep ( Galen, c173 ) : A relationship between adjacent objects in the body; an object is deep to another when it is closer to the center; the opposite of superficial. The dichotomy has been used at least since the second century by Galen; see translation by May (1968, pp. 701, 715), also see Standring (2008, p. xxii).

Ganglia ( G ; Galen, c173 ) : A ganglion is a recognizable aggregation of neurons (Waldeyer, 1891). There are marginal ganglia associated with invertebrate nerve nets, central ganglia associated with invertebrate central nerve cords, and peripheral ganglia in the invertebrate and vertebrate peripheral nervous system (Meckel, 1817). For vertebrates it has long been best practice to restrict the term ganglion (and terms derived from ganglion) to structures of the peripheral nervous system (Meckel, 1817). As Herrick wrote, "The term ‘ganglion' is also sometimes used for nuclei or centers within the brain…but this usage is objectionable, for the use of the word ganglion in vertebrate neurology should be restricted to collections of neurons outside the central nervous system, such as the ganglia of the cranial and spinal nerves and the sympathetic [autonomic] ganglia." (1915, p. 108). A prime example is the use of "basal ganglia" for cerebral nuclei (Swanson, 2000). Discovered and named in macrodissected adult mammals by Galen (c173; see translation by May , 1968, pp. 695-696).

Inner ( Galen, c173 ) : Closer to the center of an object in the body; the opposite of outer; see Standring (2008, p. xxii). The dichotomy was used at least as far back as Galen in the second century; see, for example, translations by May (1968, pp. 711, 377) and Singer (1999, p. 131). Aristotle wrote in De Partibus Animalium of parts within the body and those placed on the outside; see translation by Ogle (1912, 674, 5-6).

Outer ( Galen, c173 ) : Away from the center of an object in the body; the opposite of inner; see Standring (2008, p. xxii). The dichotomy was used at least as far back as Galen in the second century; see, for example, translations by May (1968, pp. 711, 377) and Singer (1999, p. 131). Aristotle wrote in De Partibus Animalium of parts within the body and those placed on the outside; see translation of Ogle (1912, 674, 5-6).

Radial nerve cord ( Galen, c173 ) : A topographic division that is a differentiated linear zone of the nerve net in Echinoderms with periodic small ganglia (Galen, c173) along its length, and extending into each of the (most commonly five) arms from the circumoral nerve ring. There is no convincing evidence that the Echinoderm nervous system (Monro, 1783) is divided into central nervous system (Meckel, 1817) and peripheral nervous system (Meckel, 1817); see Cobb (1995, p. 411). A cord segment between two adjacent ganglia is called a longitudinal communicating branch.

Superficial ( Galen, c173 ) : A relationship between adjacent objects in the body; an object is superficial to another when it is closer to the surface; the opposite of deep. The dichotomy has been used at least since the second century by Galen; see translation by May (1968, p. 715), also see Standring (2008, p. xxii).

Thalamus ( Galen, c173 ) : In at least one instance this term clearly referred to the inferior horn of the lateral ventricle (Vesalius, 1543); see translation by May (1968, p. 687).

Third ventricle ( V3 ; Galen, c173 ) : The part of the ventricles (Hippocrates) in the median plane (Henle, 1855) of the interbrain (Baer, 1837), continuous rostrally (Schulze, 1893) with the lateral ventricles (Vesalius, 1543) and caudally (Cleland, 1879) with the cerebral aqueduct (His, 1895). Galen (c173; see translations by May, 1968, p. 141 and Singer, 1999, p. 234) discovered and named the third ventricle in the macrodissected adult ox.