The tarsi (tarsal plates) are two comparatively thick, elongated plates of dense connective tissue, about 2.5 cm. in length; one is found in each eyelid, and contributes to its form and support. They directly abut the lid margins. [ http://en.wikipedia.org/wiki/Tarsus_(eyelids) ]
Synonyms: tarsal plate of eyelid tarsus palpebralis tarsal plate
- UMLS:C0459586 (ncithesaurus:Tarsal_Plate)
In most taxa (birds, mammals, lizards), the tarsal plate is described as a dense, fibrous connective tissue, possibly including cartilage, present within one or both of the upper and lower eyelids (Gau- thier et al., 1988; Rieppel, 2000). In humans, the tarsal plate of the upper eyelid is composed of collagens types I, III, and V, as well as glycosaminogly- cans (chondroitin sulphate 4 and 6), aggrecan, and cartilage oligomeric matrix proteins but lacks collagen type II as well as chondrocytes (Milz et al., 2005). Thus, for humans, the upper tarsal plate represents neither a truly fibrous nor a truly cartilagi- nous element but instead one that is composed of a unique transitional tissue (Milz et al., 2005). In many birds, lizards, and Sphenodon (the tuatara), the upper eyelid has lim- ited mobility and a putative tarsal plate is instead found within the lower eyelid (Underwood, 1970; Gau- thier et al., 1988).