Knee Flexors

Question 1

Biceps femoris

Answer 1

O: long head ischial tuberosity
Short head linea aspera and lateral supracondylar ridge
I: head of fibula, lateral tibial condyle
A: flexes and laterally rotates the knee, long head extends the hip
I: sciatic nerve L5, S1-S3

Question 2

Semitendinosus

Answer 2

O: ischial tuberosity
I: medial surface of the proximal tibia
A: extends the hip, flexes and medially rotates the knee
I: sciatic nerve L5, S1, S2

Question 3

Semimembranosius

Answer 3

O: ischial tuberosity
I: posterior aspect of the media, tibial condyle
A: extends the hip, flexes and medially forages the knee
I: sciatic nerve L5, S1, S2

Question 4

Sartorius

Answer 4

Origins: ASIS
Insertions: proximal medial surface of the tibia
Action: flexes, abducts, laterally rotates the thigh and medically rotates the flexed knee
Innervation: L2-L3

Question 5

Popliteus

Answer 5

O- lateral femoral condyle
I- proximal surface of posterior tibia
A- rotates knee medically and flexes the knee
I- tibial nerve, L4, S1

Question 6

Gastrocnemius

Answer 6

O- medial and lateral heads from medial and lateral femoral condyles
I- Achilles’ tendon into posterior superior calcaneus
A- knee flexion and ankle plantarflexion
I- tibial nerve S1, S2

Question 7

Plantaris

Answer 7

O- lateral supracondylar ridge of the femur and oblique popliteal ligament of knee
I- via calcaneal tendon to posterior surface of calcaneus
A- weak knee flexor and plantar flexor of foot
I- tibial S1,S2