ATLAS

ATLAS, in Anatomy the Name of the first Vertebra of the Neck, which supports the Head. See VERTEBRA and NECK.

It is so called in allusion to the celebrated Mountain Atlas in Africa, which is so high, that it seems to bear the Heavens; and to the Fable, in which, Atlas, the King of this Country is said to bear the Heavens on his Shoulders.

The Atlas has no spiny Apophyses; because the Motions of the Head don’t turn on this Vertebra, but on the second. As it is obliged to turn about as often as the Head moves round, had there been any spiny Apophyses, it would have incommoded the Motion of the Muscles in the Extension of the Head.



It is also of a finer and firmer Texture than the other Vertebrae; and it differs further from them in that those receive at one End, and are received at the other, whereas this receives at both Extremes; for two Eminences of the Occiput are inserted within its two upper Cavities, which makes its Articulation with the Head; and at the same time, two other Eminences of the second Vertebra are received within its two lower Cavities, by means of which they are articulated together.

Atlas is also a Title given to Books of universal Geography containing Maps of the known Parts of the World; as if they were viewed from the Top of that celebrated Mountain, which the Ancients esteemed the highest in the World; or rather on Account of their holding the whole World like Atlas. We have also Atlases of particular Parts, Sea-Atlases, etc.—The first Work under this Denomination was the Great Atlas of Mercator.

ATLAS