Tendons are the fibrous connective tissue structures by which muscles connect to bones (or in some cases, to the skin, as is the case with facial muscles, for example). There are as many as 267 in the human body, with different characteristics among them and not only in terms of shape and length. Suffice it to say, in fact, that while all tendons slide within fibrous sheaths, only a few are further enveloped by a sheath, called the synovial sheath, which facilitates sliding within the former, while most are surrounded by the so-called peritendinous leaflets, which have the same function as the synovial sheath but different structure.
