Anatomy (Lower Extremity)

Front 1

Psoas major

Back 1

Innervation: ventral rami of lumbar nerves L1-3

Action: flexes teh thight at the hip and an important flexor of the trunk at the hip. Acting alone, it laterally flexes the trunk

Front 2

Iliacus

Back 2

Innervation: femoral nerve (L2, L3, L4)

Action: works with psoas major (= iliopsoas muscle) which flexes the thigh at the hip. Trunk flexor

Front 3

Tensor fasciae latae

Back 3

I: superior gluteal nerve (L4 & L5)

Action: flexes, abducts, and medially rotates the thigh at the hip. Stabilizes the hip

Front 4

Sartorius

Back 4

I: femoral never (L2 & L3)

Action: flexor, abductor, and lateral rotator of hte thigh at the hip joint. Also a flexor of the leg at the knee. Helps balance the pelvis

Front 5

Rectus femoris

Back 5

I: femoral nerve (L2, L3, L4)

Action: extensor of the leg at the knee, helps flex the thigh at the hip

Front 6

Vastus lateralis

Back 6

I: femoral nerve (L2, L3, L4)

Action: extension of hte leg at the knee

Front 7

Vastus intermedius

Back 7

I: femoral nerve (L2, L3, L4)

Action: extension of the leg at hte knee

Front 8

Vastus medialis

Back 8

I: femoral nerve (L2, L3, L4)

Action: extension of the leg at the knee

Front 9

Pectineus

Back 9

I: femoral nerve (L2, L3)

Action: adducts and flexes the thight at hte hip and assists w/ medial rotation of the thigh

Front 10

Adductor longus

Back 10

I: obturator nerve via anterior branch (L2, L3, L4)

Action: adducts the thigh

Front 11

Adductor brevis

Back 11

I: obturator nerve (L2, L3, L4)

Action: adducts the thigh at the hip and can flex and medially rotate the thigh

Front 12

Obturator externus (directly under pectineus)

Back 12

I: obturator nerve (L3, L4)

Action: laterally rotates the thigh at the hip and helps steady the head of hte femur in the acetabulum of the pelvis

Front 13

Adductor magnus

Back 13

I: adductor portion is obturator nerve (L2, L3, L4). Hamstring portion is tibial portiono f sciatic nerve (L4)

Action: Powerful adductor of the thigh a the hip.

Front 14

Gracilis

Back 14

I: obturator nerve (L2, L3)

Action: adducts the thigh, flexes the leg at the knee, and is a medial rotator when the knee is flexed

Front 15

Gluteus maximus

Back 15

I: inferior gluteal nerve (L5, S1, S2)

Action: Extensor and lateral rotator of hte thight at the hip. Upper fibers assist in ABDuction while lower fibers assist in ADDuction

Front 16

Gluteus medius

Back 16

I: superior gluteal nerve (L5, S1)

Action: Abductor and medial rotator of hte thigh at the hip.

Front 17

Gluteus minimis

Back 17

I: superior gluteal nerve (L5, S1)

Action: abducts and medially rotates the thigh at the hip.

Front 18

Piriformis

Back 18

I: ventral rami of S1 and S2

Action: abducts the flexed thigh at hte hip and helps stabilize the hip

Front 19

Superior gemellus

Back 19

I: nerve tot he obturator internus (L5, S1)

Action: laterally rotate the extended thigh and abduct the flexed thigh at the hip. Also steady the femoral head in the acetabulum

Front 20

Inferior gemellus

Back 20

I: a branch ofthe nerve to the quadratus femoris (L5, S1)

Action: laterally rotate the extended thigh and abduct the flexed thigh at the hip

Front 21

Obturator internus

Back 21

I: nervet ot he obturator internus (L5, S1)

Action: laterally rotates the extended thigh at the hip and abducts the flexed thigh at the hip. Also steadies the femoral head in the acetabulum

Front 22

Quadratus femoris

Back 22

I: nerve tot he quadratus femoris (L5, S1)

Action: rotates the thigh laterally

Front 23

Semimembranosus

Back 23

I: Sciatic nerve, tibial division (L5, S1, S2)

Action: flexes the leg at the knee and rotates the flexed leg medially. Also extends the thigh at the hip.

Front 24

Semitendinosus

Back 24

I: sciatic nerve, tibial division (L5, S1, S2)

Action: flexes the leg at the knee and, when the knee is flexed, medially rotates the tibia. Also an extensor of the thigh at the hip.

Front 25

Semimembranosus

Back 25

I: sciatic nerve, tibial division (L5, S1, S2)

Action: flexes the leg at the knee and rotates the flexed leg medially. Also extends the thigh at the hip.

Front 26

Biceps femoris: short head

Back 26

I: sciatic nerve, common fibular (peroneal) division (L5, S1, S2)

Action: flexes the leg at the knee

Front 27

Biceps femoris: long head

Back 27

I: sciatic nerve, tibial division (L5, S1, S2)

Action: flexes the leg at the knee, and rotates teh tibi laterally from the femur after the knee is flexed

Front 28

Fibularis (peroneus) longus

Back 28

I: superficial fibular (peroneal) nerve (L5, S1, S2)

Action: everts the foot and is a weak plantar flexor of the foot at the ankle

Front 29

Fibularis (peroneus) brevis

Back 29

I: superficial fibular (peroneal) nerve (L5, S1, S2)

Action: everts the foot and acts as a weak plantar flexor of hte foot at the ankle

Front 30

Tibialis anterior

Back 30

I: deep fibular (peroneal) nerve (L4, L5)

Action: dorsiflexes the foot at the ankle and inverts the foot at the subtalar and midtarsal joints

Front 31

Extensor hallucis longus

Back 31

I: deep fibular (peroneal) nerve (L5, S1)

Action: extends the big toe, assists in dorsiflexion of the foot at the ankle, and is a weak inverter

Front 32

Extensor digitorum longus

Back 32

I: deep fibular (peroneal) nerve (L5, S1)

Action: extends the proximal phalanges of hte later 4 toes and is a dorsiflexor of hte foot at the ankle