Hamstrings are a group of three muscles located at the back of thighs, which can be divided into two more- or- less symmetrical parts: medial and lateral. All of them start at the ischial tuberosity, but they end at the opposite sides of the below-knee area.
The medial group consist of the semitendinosus and semimembranosus muscles, which pass the knee and end at the tibia.
The semimembranosus muscle start as a thin, broad, membranosus structure. It is positioned posteromedial to the semitendinosus. It originates from the superolateral facet on the rough area on the ischial tuberosity. [1]. Near its insertion, the tendon trifurcates (but some researchers identify six distinct insertions) and inserts to: medial tibia condyle (primary attachment), popliteal fascia and oblique popliteal ligament.
The semitendinosus is named for its long insertion tendon. It originates from the lower medial facet of the lateral section of the ischial tuberosity and the medial tendon of the long head of biceps femoris. [2] The semitendinosus is blend with the tendons of gracilis and sartorius muscles, inserting at proximal end of tibia below the medial condyle. This place is called the pes anserinus.
In the lateral group is located the biceps femoris, which passes the knee and ends at the fibula. More precise- on lateral aspect of head of fibula. While the main bulk of this muscle (called the long head) starts at the same place as the other hamstrings, there is also a shorter part of this muscle (called the short head) which starts at the femur itself on lateral supracondylar line and linea aspera. [3]
All hamstring muscles are responsible for hip extension (except for the short head of the biceps femoris) and knee flexion. Additionally, the semitendinosus and semimembranosus also contribute to internal rotation of thigh, and the biceps femoris is also external rotator of leg. [4]
- Palastanga, Nigel, i Roger Soames. Anatomy and Human Movement: Structure and Function. 6th ed., Churchill Livingstone/Elsevier, 2012
- Sato, Kengo, i in. „Anatomical Study of the Proximal Origin of Hamstring Muscles”. Journal of Orthopaedic Science, t. 17, nr 5, September 2012, s. 614–18. DOI.org (Crossref), https://doi.org/10.1007/s00776-012-0243-7
- Netter, Frank H., Carlos A. G. Machado. Atlas of Human Anatomy. edited by John T. Hansen., Seventh edition, Standard edition, Elsevier, 2019
- Soames, Roger. Anatomy and Human Movement: Structure and Function. Eighth edition., Elsevier, 2024