The pastern is a part of the leg of a horse

Horse

The horse is one of two extant subspecies of Equus ferus, or the wild horse. It is a single-hooved mammal belonging to the taxonomic family Equidae. The horse has evolved over the past 45 to 55 million years from a small multi-toed creature into the large, single-toed animal of today...

 between the fetlock

Fetlock

Fetlock is the common name for the metacarpophalangeal and metatarsophalangeal joints of horses, large animals, and sometimes dogs. It is formed by the junction of the third metacarpal or metatarsal bones proximad and the proximal phalanx distad...

 and the top of the hoof

Hoof

A hoof , plural hooves or hoofs , is the tip of a toe of an ungulate mammal, strengthened by a thick horny covering. The hoof consists of a hard or rubbery sole, and a hard wall formed by a thick nail rolled around the tip of the toe. The weight of the animal is normally borne by both the sole...

. It incorporates the long pastern bone (proximal phalanx) and the short pastern bone (middle phalanx), which are held together by two sets of paired ligament

Ligament

In anatomy, the term ligament is used to denote any of three types of structures. Most commonly, it refers to fibrous tissue that connects bones to other bones and is also known as articular ligament, articular larua, fibrous ligament, or true ligament.Ligament can also refer to:* Peritoneal...

s to form the pastern joint (proximal interphalangeal joint). Anatomically homologous to the two largest bones found in the human finger

Finger

A finger is a limb of the human body and a type of digit, an organ of manipulation and sensation found in the hands of humans and other primates....

, the pastern was famously mis-defined by Samuel Johnson

Samuel Johnson

Samuel Johnson , often referred to as Dr. Johnson, was an English author who made lasting contributions to English literature as a poet, essayist, moralist, literary critic, biographer, editor and lexicographer...

 in his dictionary

A Dictionary of the English Language

Published on 15 April 1755 and written by Samuel Johnson, A Dictionary of the English Language, sometimes published as Johnson's Dictionary, is among the most influential dictionaries in the history of the English language....

 as "the knee of a horse".