Myology (knee)

origin of the biceps femoris long head

ischial tuberosity (the bony prominence located on the lower part of the pelvis)

origin of biceps femoris short head

linea aspera and supracondylar line of femur

insertion of biceps femoris long head & short head

Lateral head of fibula

innervation of the biceps femoris long head

tibial division of sciatic nerve (S1)

innervation of the biceps femoris short head

common fibular division of the sciatic nerve (S1)

Action of the biceps femoris long & short head

flexes the knee joint and rotates it laterally when the knee is flexed; and extends the hip joint

origin of the semimembranosus

Ischial tuberosity

insertion of semimembranosus

posterior part of the medial condyle of the tibia

innervation of the Semimembranosus

tibial division of the sciatic nerve (L5, S1)

Action of the Semimembranosus

extend the hip joint; flex the knee joint and rotate the knee medially when the knee is flexed; when the hip and knee are flexed, can extend the trunk

origin of the semitendinosus

ischial tuberosity

insertion of the semitendinosus

medial surface of superior part of the tibia (Pes Anserine)

innervation of the semitendinosus

tibial division of the sciatic nerve (L5, S1)

Action of the Semitendinosus

extend the hip joint; flex the knee joint and rotate the knee medially when the knee is flexed; when the hip and knee are flexed, can extend the trunk

origin of the Sartorius

Anterior superior iliac spine (ASIS)

Insertion of the Sartorius

superior part of the medial surface of the tibia (pes anserine)

innervation of the sartorius

femoral nerve

action of the Sartorius

flexes, abducts and laterally rotates the hip joint; and flexes the knee

origin of the Gracilis

Body and inferior ramus of the pubis

Insertion of the gracilis

Superior part of the medial surface of the tibia (pes anserine)

innervation of the gracilis

obturator nerve (L2)

action of the gracilis

adducts the hip joint; flex the knee joint and rotate it medially

origin of the rectus femoris

Anterior inferior iliac spine (AIIS) and ilium superior to the acetabulum

insertion of the rectus femoris

Via quadriceps tendon to base of patella; indirectly via patellar ligament to tibial tuberosity (vastus medialis and lateralis also attach to tibia and patella via aponeurosis)

innervation of the rectus femoris

femoral nerve (L3, L4)

Action of the rectus femoris

extends the knee; also stabilizes the hip and helps the ilopsoas flex the hip joint

origin of the Vastus lateralis

greater trochanter and lateral lip of linea aspera

insertion of the Vastus lateralis

Via quadriceps tendon to base of patella; indirectly via patellar ligament to tibial tuberosity; vastus medialis and lateralis also attach to tibia and patella via aponeurosis

innervation of the Vastus lateralis

femoral nerve (L3, L4)

action of the Vastus lateralis

extends the knee

origin of the Vastus medialis

intertrochanteric line and medial lip of the linea aspera

insertion of the Vastus medialis

Via quadriceps tendon to base of patella; indirectly via patellar ligament to tibial tuberosity; vastus medialis and lateralis also attach to tibia and patella via aponeurosis

innervation of the Vastus medialis

femoral nerve (L3, L4)

action of the Vastus medialis

extends the knee

origin of the popliteus

lateral surface of the lateral condyle of the femur and the lateral meniscus

insertion of the popliteus

posterior surface of the tibia superior to the soleal line

innervation of the popliteus

tibial nerve

action of the popliteus

Weakly flexes knee and unlocks in by laterally rotating femur on fixed tibia, medially rotates tibia in open kinetic chain