Criteria for Identifying Hamstrings
Hamstrings are a group of muscles that meet specific criteria to be classified as such. The three muscles that meet these criteria and are considered true hamstrings are the biceps femoris, semimembranosus, and semitendinosus. These muscles fulfill all the necessary conditions to be categorized as hamstrings. However, the adductor magnus, while meeting some of the criteria, does not extend far enough to be classified as a hamstring.
Biceps Femoris: The Powerful Hamstring
The biceps femoris is an important muscle in the human body, specifically categorized as a hamstring. It consists of two heads – the long head and the short head, each with its own unique functions. While the long head is a true hamstring, the short head falls slightly short of meeting the criteria.
One of the primary functions of the biceps femoris is to assist in knee flexion. However, due to the fact that the short head does not cross over the hip joint, it is unable to contribute to hip extension. Both heads of the biceps femoris also play a role in rotating the knee outward or laterally.
When it comes to hip extension, the biceps femoris is the primary contributor among the hamstrings. It has three lower attachment sites, namely the lateral condyle of the tibia, the head of the fibula, and the deep fascia within the leg. This muscle’s numerous attachment sites make it more prone to tearing compared to the other hamstrings.