What are the hamstring muscles?

The hamstring muscles are a group on the back of the thigh that includes the semitendinosus, semimembranosus, biceps femoris (long head), and the ischial head of adductor magnus. They all originate from the ischial tuberosity and act on both the hip and knee joints.

What are the main actions of the hamstring muscles?

The hamstrings primarily flex the knee joint and extend the hip joint (especially during walking). They also provide dynamic support to limit hip flexion when the knee is extended, such as during toe-touch movements.

Why is the short head of biceps femoris not considered a hamstring muscle?

The short head of biceps femoris is excluded from the hamstring group because it has a different origin (lateral lip of linea aspera) and nerve supply (common peroneal division of sciatic nerve), unlike the other hamstrings which share a common origin and tibial nerve innervation.

What nerve supplies the hamstring muscles?

Most hamstring muscles are supplied by the tibial division of the sciatic nerve. The exception is the short head of biceps femoris, which is innervated by the common peroneal division of the sciatic nerve.

What is the clinical significance of hamstring paralysis?

Paralysis of the hamstrings can cause postural instability, leading to forward falling because the gluteus maximus alone cannot maintain posture. Historically, "hamstringing" was a disabling tactic in warfare to impair mobility by cutting these tendons.

Where do the hamstring muscles insert?

Hamstring insertions vary: biceps femoris inserts at the head of the fibula, semitendinosus on the upper medial surface of the tibia, semimembranosus on the posterior medial condyle of the tibia, and the ischial head of adductor magnus on the adductor tubercle of the femur.

Why is the ischial head of adductor magnus grouped with the hamstrings?

The ischial head of adductor magnus is grouped with the hamstrings due to developmental and functional reasons, even though it inserts on the femur. It shares a common origin (ischial tuberosity) and nerve supply (tibial division of sciatic nerve) with the other hamstrings.

Posterior Thigh Muscles – Hamstrings Anatomy

❓ Frequently Asked Questions