Conjoint tendon of semitendinosus and long head of biceps femoris

The conjoint tendon of semitendinosus and long head of biceps femoris refer to the common origin of these two muscles from the ischial tuberosity.

Origin

• The semitendinosus and long head of the biceps femoris both arise from the inferomedial impression of the ischial tuberosity by a common (conjoined) tendon. This tendon is thick and broad, attaching just medial to the origin of the adductor magnus (hamstring part) muscle.

• The conjoined tendon is continuous inferiorly with the individual muscle bellies, which diverge as they descend in the posterior thigh.

Course

• After originating together, the two muscles descend superficially in the posterior thigh, separated by a fascial plane as they approach the knee region:

  • Biceps femoris (long head): Passes laterally to insert into the head of the fibula.

  • Semitendinosus: Passes medially to insert into the superior medial surface of the tibia (forming part of the pes anserinus).

Innervation

• Both muscles are innervated by the tibial division of the sciatic nerve.