Hip & Knee Muscle Actions

Question 1

Gluteus Maximus (upper and lower parts)

Answer 1

upper part: extends, abducts and laterally rotates the hip

Lower part: extends, adducts and laterally rotates the hip

Question 2

Gluteus Medius (anterior and posterior parts)

Answer 2

Anterior part: flex, abducts and medially rotates the hip

Posterior part: extends, abducts and laterally rotates the hip

Question 3

Gluteus minimus

Answer 3

flexes, abducts and medially rotates the hip

Question 4

Psoas Major

Answer 4

flexes and medially rotates the hip

* cannot ab. or ad. the hip.

Question 5

Iliacus

Answer 5

Flexes and medially rotates the hip

* cannot ab. or ad. the hip.

Question 6

Rectus Femoris

Answer 6

Flexes the hip
(LOP suggests hip abduction too)

Extends the knee.

• cannot medially or laterally rotate the hip.

Question 7

Obturator Internus

Answer 7

Laterally rotates the hip

* cannot flex/ext, or ab/ad the hip.

Question 8

Superior Gemellus

Answer 8

Laterally rotates the hip

* cannot flex/ext, or ab/ad the hip.

Question 9

Inferior Gemellus

Answer 9

Laterally rotates the hip

* cannot flex/ext, or ab/ad the hip.

Question 10

Piriformis

Answer 10

Abducts and laterally rotates the hip

* cannot flex/ext the hip

Question 11

Obturator Externus

Answer 11

Adducts and laterally rotates the hip

* cannot flex/ext the hip

Question 12

Quadratus Femoris

Answer 12

Extends, adducts and laterally rotates the hip

Question 13

Pectineus

Answer 13

Flexes, adducts and medially (internally) rotates the hip

Question 14

Adductor Magnus

Answer 14

True adductor part: flexes the hip.
Ex-hamstrings part: extends the hip.

All parts: Adducts and internally (medially) rotate the hip.

Question 15

Adductor brevis

Answer 15

Adducts, flexes and internally rotates the hip

Question 16

Adductor longus

Answer 16

Adducts, flexes and internally rotates the hip

Question 17

Tensor fascia lata

Answer 17

Abducts, flexes and medially rotates the hip

Question 18

Sartorius

Answer 18

Abducts, flexes and laterally rotates the hip.

Flexes and medially rotates the leg at the knee

Question 19

Semimembranosus

Answer 19

Extends the hip and flexes the knee

Question 20

Semitendinosus

Answer 20

Extends the hip and flexes the knee

Question 21

Long head biceps femoris

Answer 21

Extends the hip and flexes the knee

Question 22

Short head biceps femoris

Answer 22

Flexes the knee and laterally rotates the flexed leg

Question 23

popliteus

Answer 23

Medially rotates the leg relative to the femur.

Unlocks the terminally locked knee at the first stage of knee flexion from full extension

Question 24

Gracilis

Answer 24

Adducts, flexes and internally rotates the hip

Knee flexion and medial (internal) rotation around the the knee joint when its in a semiflexed position

Question 25

Vastus lateralis

Answer 25

Extends the knee; pulls patella up and outward

Question 26

Vastus Medialis

Answer 26

Extends the knee; pulls the patella up and inward

Question 27

Vastus intermedius

Answer 27

Extends the knee

Question 28

Articularis Genu

Answer 28

Contract during knee extension

Pulls the loosening knee joint capsule superiorly to prevent it from becoming impinged between the patella and the femur