Choroid Choroid The choroid, also known as the choroidea or choroid coat, is the vascular layer of the eye, containing connective tissues, and lying between the retina and the sclera. The human choroid is thickest at the far extreme rear of the eye (at 0.2 mm), while in the outlying areas it narrows to 0.1 mm. The choroid provides oxygen and nourishment to the outer layers of the retina. Along with the ciliary body and iris, the choroid forms the uveal tract. The structure of the choroid is generally divided into four layers (classified in order of furthest away from the
The Layer Quaternity The Layer Quaternity The Layer Quaternity are four marble sculpture figurines approximately in height located on the two columns of the Layer Monument, an early 17th-century polychrome mural monument () which was installed in the Church of Saint John the Baptist, Maddermarket, Norwich to the memory of Christopher Layer (1531–1600). The quartet of figurines sculptured in marble, "Pax, Gloria, Vanity, Labor" exhibit primary thematic concerns and stylistic attributes of Northern Mannerist art, namely, portraiture of animated human movement, variety and multiplicity, often set in the Classical or mythological world, and inclined towards esoteric concepts. The Layer Quaternity ("circa" 1598–1604) share