Where is the longest muscle in the human body located?

The sartorius muscle is the longest muscle in the human body. It is a long, thin, superficial muscle that runs down the length of the thigh in the anterior compartment.

The name Sartorius comes from the Latin word sartor, meaning tailor, and it is sometimes called the tailor's muscle. This name was chosen in reference to the cross-legged position in which tailors once sat. In French, a muscle name itself "couturier" comes from this specific position which is referred to as "sitting as a tailor" (in French: "s'asseoir en tailleur"). There are other hypotheses as to the genesis of the name. One is that it refers to the location of the inferior portion of the muscle being the "inseam" or area of the inner thigh that tailors commonly measure when fitting trousers. Another is that the muscle closely resembles a tailor's ribbon. Additionally, antique sewing machines required continuous crossbody pedaling. This combination of lateral rotation and flexion of the hip and flexion of the knee gave tailors particularly developed sartorius muscles.