Semitendinosus Muscle Anatomy

The semitendinosus muscle, as its name indicates, is half tendinous, it’s one of the hamstring muscles group. It has a fusiform belly that is usually interrupted by a tendinous intersection and a long, cord-like tendon that begins approximately two thirds of the way down the thigh.

Distally, the tendon attaches to the medial surface of the superior part of the tibia as part of the pes anserinus formation in conjunction with the tendinous insertions of the sartorius and gracilis

The hamstring muscles are located in the posterior thigh compartment, these muscles are:

1. Semitendinosus,
2. Semimembranosus,
3. Biceps femoris (long head).

See Also: Semimembranosus Muscle Anatomy & Function

The semitendinosus and gracilis muscle tendons are commonly used as an alternative to the bone-patellar-tendon-bone graft (BPTB) for anterior cruciate ligament reconstruction.

Semitendinosus Muscle Anatomy

Semitendinosus Muscle originates from common tendon with long head of biceps femoris from superior medial quadrant of the posterior portion of the ischial tuberosity, and inserts on the superior aspect of medial portion of tibial shaft (the so called pes anserinus tendon insertion).

The pes anserinus tendon consists of the semitendinosus, gracilis, and sartorius conjoined tendon.

It gets its innervation from the Tibial nerve (L5, S1, S2) (as other hamstrings muscle). It also gets its blood supply from the perforating branches of profunda femoris artery, inferior gluteal artery and the he superior muscular branches of popliteal artery.

The Semitendinosus function is to extends the thigh and flexes the knee joint, it also rotates the tibia medially, especially when the knee is flexed.

Origin	From common tendon with long head of biceps femoris from superior medial quadrant of the posterior portion of the ischial tuberosity
Insertion	Superior aspect of medial portion of tibial shaft (pes anserinus)
Innervation	Tibial nerve (L5, S1, S2)
Blood Supply	Perforating branches of profunda femoris artery Inferior gluteal artery The superior muscular branches of popliteal artery
Action	Extends the thigh and flexes the knee Rotates the tibia medially, especially when the knee is flexed

References & More

1. Clinically Oriented Anatomy, 8th Edition.
2. Mathew K, Pillarisetty LS. Anatomy, Bony Pelvis and Lower Limb: Thigh Semitendinosus Muscle. [Updated 2023 May 29]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK539862/