上関節面 - Facies articularis superior
The superior articular surface (superior facet)s are of large size, oval, concave, and approach each other in front, but diverge behind: they are directed upward, medialward, and a little backward, each forming a cup for the corresponding condyle of the occipital bone, and are admirably adapted to the nodding movements of the head. Not infrequently they arepartially subdivided by indentations which encroach upon their margins.
This definition incorporates text from a public domain edition of Gray's Anatomy (20th U.S. edition of Gray's Anatomy of the Human Body, published in 1918 – from http://www.bartleby.com/107/).
一般解剖学 > 骨、骨格系 > 軸骨格 > 脊柱 > 頚椎[C1－C7] > 環椎[C1]；第一頚椎 > 外側塊 > 上関節面