Hamstring
In human anatomy, a hamstring (/ˈhæmstrɪŋ/) is any one of the three posterior thigh muscles between the hip and the knee (from medial to lateral: semimembranosus, semitendinosus and biceps femoris).[3] [4]
Etymology[edit]
The word "ham" is derived from the Old English ham or hom meaning the hollow or bend of the knee, from a Germanic base where it meant "crooked". It gained the meaning of the leg of an animal around the 15th century.[5] String refers to tendons, and thus, the hamstrings are the string-like tendons felt on either side of the back of the knee.[6]
Function[edit]
The hamstrings cross and act upon two joints – the hip and the knee – and as such they are termed biarticular muscles.
Semitendinosus and semimembranosus extend the hip when the trunk is fixed; they also flex the knee and medially (inwardly) rotate the lower leg when the knee is bent.
The long head of the biceps femoris extends the hip, as when beginning to walk; both short and long heads flex the knee and laterally (outwardly) rotate the lower leg when the knee is bent.
The hamstrings play a crucial role in many daily activities such as walking, running, jumping, and controlling some movement in the gluteus. In walking, they are most important as an antagonist to the quadriceps in the deceleration of knee extension.
Clinical significance[edit]
Sports running injuries[edit]
A common running injury in several sports, excessive stretch of a hamstring results from extensive hip flexion while the knee is extended.[4][8] During sprinting, a hamstring injury may occur from excessive muscle strain during eccentric contraction late in the leg swing phase.[4][8] The overall incidence of a hamstring injury in sports and professional dancers is about two per 1000 hours of performance.[4] In some sports, a hamstring injury occurs at the incidence of 19% of all sports injuries, and results in an average time loss from competition of 24 days.[4]