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Human nail anatomy.jpg
A. Nail plate; B. lunula; C. root; D. sinus; E. matrix; F. nail bed; G. hyponychium; H. free margin.
Longitudinal section through nail and its nail groove (sulcus).
Latin Eponychium
Gray's p.1067
Anatomical terminology

In human anatomy, the eponychium [Greek epi (on, upon) + onychion (little claw)], is the thickened layer of skin surrounding fingernails and toenails. Its function is to protect the area between the nail and epidermis from exposure to bacteria. The vascularization pattern is similar to that of perionychium.[1]

In hoofed animals, the eponychium is the deciduous hoof capsule in fetuses and newborn foals, and is a part of the permanent hoof in older animals.[2]


  1. ^ Sangiorgi S, Manelli A, Congiu T, et al. (2004). "Microvascularization of the human digit as studied by corrosion casting". J. Anat. 204 (2): 123–31. doi:10.1111/j.1469-7580.2004.00251.x. PMC 1571248. PMID 15032919. 
  2. ^ Bragulla, H. (Mar 1991). "The deciduous hoof capsule (Capsula ungulae decidua) of the equine fetus and newborn foal". Anat Histol Embryol. 20 (1): 66–74. PMID 1877762.