Action.

Muscle.

Origin.

Insertion.

Nerve-supply.

Flexion

Hamstrings, consisting of-

Biceps

See Hip-Joint

Semimembranosus

Semiten-dinosus

Sartorius Gracilis

Gastrocnemius

By two heads-(1) On the upper part of the external condyle and supracondyloid ridge; (2) from the space between the internal condyle and the adductor tubercle

The tendo Achillis inserted in the middle part of the posterior surface of the os calcis

Tibial

Plantaris

From the lower third of the outer supracondyloid ridge

The tendo Achillis, or a separate insertion on its inner side

Tibial

Popliteus

By a tendon from the outer surface of the external condyle

The triangular surface on the upper part of the posterior surface of the tibia above the oblique line

Tibial

Extension

Quadriceps extensor, consisting of four parts

Rectus femoris

The straight head from the anterior inferior spine of the ilium and the reflected head from a groove just above the acetabulum

The upper border of the patella and the ligamentum patellae

Anterior crural

Vastus externus

From the anterior surface of the shaft of the femur in front of the great trochanter round to the outer lip of the linea aspera and its upper half; deep fascia

The upper and outer border of the patella and the ligamentum patellae

Anterior crural

Extension

Vastus internus

From the lower two-thirds of the intertrochanteric line, the inner lip of the linea aspera, and upper two-thirds of the line from the linea aspera to the inner condyle ; deep fascia

The upper and inner border of the patella and the ligamentnum patellae

Anterior crural

Crureus

(vastus intermedius)

From the anterior and outer surfaces of the upper two-thirds of the shaft of the femur ; the lower half of the outer lip of the linea aspera and the line leading to the outer condyle ; deep fascia

The deep surface of the tendons of rectus femoris and the vasti, and the ligamentum patellae

Anterior crural