THE POSTERIOR THIGH MUSCLES

ORIGIN            INSERTION           INNERVATION         ARTERY             ACTION

Biceps Femoris:

a.  Long Head          Ischial tuberosity               Tendon insertion     Tibial L5, part of        Profunda             Flexor of

                                                                          head of fibula         sciatic n, S1, S2          Femoris           leg at thigh

b.  Short Head         Lat. Lip of linea aspect       Head of Fibula       Common Peroneal L5  Profunda           Flexor

                               + lat inter muscular                                            part of sciatic N. S2    Femoris   

                                septum

Semitendinosus       Ischial Tuberosity               Passes downward Tibia part of sciatic  Profunda            Flexor of

                                                                           Medial to biceps       sciatic N L5, S1, S2  Femoris         leg on thigh

                                                                          & post to semi- membranosis.  Its tendon passes behind the knee

                                                                          joint and curves forward to insert  into med. Aspect of bd of fibula

                                                                          anserine bursa.  Shares with the gracilis and  sartorious.

Semimembranosus  Lower portion of Ischial    Tubercle on the      Tibial part of sciatic N   Profunda    Flexor of leg

                                Tuberosity                   post aspect of medial    Sciatic N. L5, S1, S2    Femoris  

The Biceps Femoris, Semitendinosus, and Semimembranosus are known as the Hamstring Muscles.  They are flexors of the leg and extensors of the thigh.  Further, It will be noted that if one cut the Tibial nerve a knee weakness in flexion will occur but the hamstrings will remain stable.                                                                                                                                                           . 

by Dr. Scott David Neff MSOM MPS-BT DC DABCO CFE FFAAJTS 09-30-2004