Second Order: U2 T2

Rectus Femoris

Action: Extends leg

Origin: Illiac Spine
Insertion: Quadratic tendon
Innervation: Femoral N

Sartorius

Action: Flex thigh
Origin: AP illiac spine
Insertion: Tibial Tuberosity
Innervation: Femoral N

Tensor Fasciae Latae

Action: abducts and medially rotates thigh

Origin: Illiac Crest
Insertion: Illiotibial Tract/Band
Innervation: Superior Gluteal Nerve

Adductor Longus

Action: Adducts and flexes thigh
Origin: Pubis
Insertion: Femur
Innervation: Obturator N

Semitendinosus

A: Extends thigh and flexes leg at the knee joint

O: Ischial tuberosity

I: Proximal medial surface of tibia

Inn: Tibial division of sciatic nerve (L4–S1 fibers)

Tibialis Anterior M

A: Dorsiflexes foot; inverts foot

O: Lateral condyle and proximal shaft of tibia; interosseous membrane

I: Metatarsal I and first (medial) cuneiform
Inn: Deep fibular nerve (L4–S1)

Fibularis tertius M

A: Dorsiflexes foot; weakly everts foot

O: Anterior distal surface of fibula; interosseous membrane

I: Base of metatarsal V

Inn: Deep fibular nerve (L5–S1)

Gastrocnemius M

A: Flexes leg at the knee joint; plantar flexes foot
O: Superior posterior surfaces of lateral and medial condyles of femur

I: Calcaneus (via calcaneal tendon)
Inn: Tibial nerve (L4–S1 fibers)

Tibialis posterior

A: Plantar flexes foot; inverts foot
O: Fibula, tibia, and interosseous membrane

I: Metatarsals II–IV; navicular bone; cuboid bone; all cuneiforms
Inn: Tibial nerve (L5–S1 fibers)

Extensor digitorum brevis

A: Extends MP, PIP, and DIP joints of toes 2–4
O: Calcaneus and inferior extensor retinaculum
I: Middle phalanges of toes 2–4

Inn: Deep fibular nerve (S1–S2 fibers)