LE - Posterior Thigh, Leg and Foot

Question 1

Biceps Femoris

Answer 1

O: Long head – Ischial tuberosity
Short head – Distal aspect of the lateral lip of linea aspera

I: Lateral side of the head of the fibula

A: All heads: Knee flexion and some lateral rotation of the leg at the knee joint;
Long head: Extend the hip, lateral rotation of the thigh at hip joint

N: Long head: Sciatic (tibial branch): L5,S1,S2 Short head: Sciatic (peroneal branch): L5,S1,S2

Question 2

Semitendinosus

Answer 2

O: Ischial tuberosity

 I: Medial surface of proximal tibia at the pes anserine tendon

A: Medially rotate the flexed knee, extend the hip, assist to medial rotate the hip, tilt the pelvic posteriorly

N: Sciatic nerve (tibial branch) (L5, S1, S2)

Question 3

Semimembranosus

Answer 3

O: Ischial tuberosity

I: Posterior surface of medial tibial condyle (some slips into oblique popliteal ligament inserting on lateral condyle)

A: Medially rotate the flexed knee, extend the hip, assist to medially rotate the hip, tilt the pelvis posteriorly

N: Sciatic nerve (tibial branch) (L5, S1, S2)

Question 4

Tibialis anterior

Answer 4

O: Lateral condyle of tibia; proximal, lateral surface of tibia and interosseous membrane

I: Medial and inferior surfaces of medial cuneiform and adjacent surfaces on base of 1st metatarsal

A: Dorsiflexion of foot at the ankle joint; inversion of foot; dynamic support of the medial arch of
foot

N: Deep (peroneal) fibular nerve (L4, L5)

Question 5

Extensor hallucis longus

Answer 5

O: Middle one-half of medial surface of fibula and adjacent surface of interosseous membrane

I: Dorsal surface of base of distal phalanx of great toe 

A: Extension of the great toe; dorsiflexion of foot at the ankle; invert the foot

N: Deep fibular (peroneal) nerve (L5, S1)

Question 6

Extensor digitorum longus

Answer 6

O: Proximal one-half of medial surface of fibula, interosseous membrane and lateral tibial condyle

I: Bases of distal and middle phalanges of lateral four toes via dorsal digital expansion

A: extension of lateral four toes and dorsiflexion of foot (with some eversion)

N: Deep fibular (peroneal) nerve (L5, S1)

Question 7

Extensor digitorum brevis (The portion to the great toe is the Extensor Hallicus Brevis)

Answer 7

O: Superolateral surface of the calcaneus

I: Base of proximal phalanx of great toe and lateral sides of the tendons of extensor digitorum
longus of 2nd to 4th toes

A: Extension of metatarsophalangeal and IP joints of great toe and extension of at 2nd to 4th toes

N: Deep fibular (peroneal) (L4, L5, S1)

Question 8

Gastrocnemius

Answer 8

O: Medial head – posterior surface of distal femur just superior to medial condyle
Lateral head – upper posterolateral surface of lateral femoral condyle

I:  Posterior surface of calcaneous via calcaneal tendon

A: Plantarflexion at the ankle and flexion at the knee

N: Tibial nerve (S1, S2)

Question 9

Soleus

Answer 9

O: Soleal line and medial border of the tibia; proximal, posterior aspect of the fibula head and adjacent surfaces of neck and proximal shaft; tendinous arch between tibial and fibular attachment

I: Posterior surface of calcaneous via calcaneal tendon

A: Plantarflexion at the ankle and flexion at the knee

N: tibial nerve (S1, S2)

Question 10

Plantaris

Answer 10

O: Inferior part of lateral supracondylar line of femur and oblique popliteal ligament of knee

I: Posterior surface of calcaneous via calcaneal tendon

A: plantarflexion at the ankle and flexion at the knee; weak plantar flexion of ankle, weak flexion of the knee

N: Tibial nerve (S1, S2)

Question 11

Popliteus

Answer 11

O: Lateral surface of the lateral femoral condyle and lateral meniscus

I: Posterior surface of proximal tibial, superior to soleal line

A: stabilizes knee joint (resists lateral rotation of tibia on femur); unlocks knee joint (laterally
rotates femur on fixed tibia or medially rotates the tibia on a fixed femur), weak knee flexion

N: Tibial nerve (L4, L5, S1)

Question 12

Flexor hallicus longus

Answer 12

O: Middle half of the posterior surface of fibula and adjacent interosseous membrane

I: Plantar surface of distal phalanx of great toe

A: flexion of great toe (at MTP and IP joints); Weak plantar flexion of ankle; Invert the foot

N: tibial nerve (S2, S3)

Question 13

Flexor digitorum longus

Answer 13

O: Middle portion of the medial side of posterior surface of the tibia

I: Plantar surfaces of bases of distal phalanges of the lateral four toes

A: flexion of lateral four toes at MTP and IP joints; Weak plantar flexion of the ankle; invert the foot

N: Tibial nerve (S2, S3)

Question 14

Tibialis Posterior

Answer 14

O: Posterior surfaces of interosseous membrane and adjacent regions of tibia and fibula, inferior to the soleal line

I: Primarily to tuberosity of navicular and adjacent region of medial cuneiform; some tendinous attachment to the MT bases 2-4 and other tarsal bones

A: Inversion and plantarflexion of the foot at TCJ; support medial arch of foot during walking

N: Tibial nerve (L4, L5)

Question 15

Peroneus (fibularis) longus

Answer 15

O: Proximal two-thirds of the lateral surface of the fibula, head of fibula

I: Base of the first metatarsal and medial cuneiform

A: Eversion of foot, weak plantarflexion; support arches of foot

N: Superficial fibular nerve (L5, S1, S2)

Question 16

Peroneus (fibularis) brevis

Answer 16

O: Distal two-thirds of the lateral surface of shaft of fibula

I: Tuberosity at the 5th metatarsal

A: Eversion of the foot and weak plantarflexion of the ankle

N: Superficial fibular nerve (L5, S1, S2)

Question 17

Peroneus (fibularis) tertius

Answer 17

O: Distal part of medial surface of fibula

I: Dorsomedial surface of base of 5th metatarsal

A: dorsiflexion and eversion of the foot

N: deep fibular nerve (L5, S1)

Question 18

Abductor Hallicus (1st Layer)

Answer 18

O:Medial process of calcaneus and plantar aponeurosis

I: Proximal phalanax of the first toe (medial surface) and medial sesamoid bone

A: Abduct the first toe (MTP joint) and assist to flex the first toe

N: Medial plantar nerve from the tibial nerve (S2, S3)

Question 19

Flexor digitorum brevis (1st Layer)

Answer 19

O: Medial process of calcaneal tuberosity and plantar aponeurosis

I: Sides of plantar surface of middle phalanges of 2nd to 5th toes

A: Flexion of lateral four toes at proximal interphalangeal joint

N: medial plantar nerve from the tibial nerve (S2, S3)

Question 20

Abductor digiti minimi (1st layer)

Answer 20

O: lateral and medial process of calcaneal tuberosity and plantar aponeurosis

I: Lateral side of base of proximal phalanx of little toe

A: Abduction and flexion of the 5th toe at the metatarsophalangeal joint

N: Lateral plantar nerve from the tibial nerve (S2, S3)

Question 21

Quadratus plantae (2nd layer)

Answer 21

O: Medial surface of calcaneus and lateral process of calcaneal tuberosity

I: Lateral side of tendon of flexor digitorum longus

A: Assist flexor digitorum longus in flexing 2nd to 5th toes, changing the angle of force application to be more linear

N: Lateral plantar nerve from tibial nerve (S2, S3)

Question 22

Lumbricales (2nd layer)

Answer 22

O: Tendons of flexor digitorum longus

I: Medial slips into extensor hoods of 2nd to 5th toes

A: Flexion of metatarsophalangeal joint and extension of interphalangeal joints of toes 2-5

N: 1st lumbrical – medial plantar nerve from the tibial nerve (S2, S3)
     2nd to 4th lumbrical -  lateral plantar nerve from the tibial nerve (S2, S3)

Question 23

Flexor hallicus brevis (3rd layer)

Answer 23

O: Plantar surface of the cuboid, and lateral cuneiforms; tendon of the tibialis posterior

I: Lateral and medial sides of base of proximal phalanx of the great toe via sesamoids

A: Flexion of the metatarsophalangeal joint of the great toe

N: Medial plantar nerve from tibial nerve (S2, S3)

Question 24

Adductor hallicus (3rd layer)

Answer 24

O: Transverse head – ligaments associated with metatarsophalangeal joints of lateral three toes
Oblique head – bases of 2nd to 4th metatarsals

I: Lateral side of base of proximal phalanx of great toe

A: Adduction of the great toe at metatarsophalangeal joint and maintain transverse arch, weak flexion

N: lateral plantar nerve from tibial nerve (S2, S3)

Question 25

Flexor digiti minimi brevis (3rd layer)

Answer 25

O: Base of the 5th metatarsal and related sheath of fibularis longus tendon

I: Lateral side of base of proximal phalanx of little toe

A: Flexion of little toe at the metatarsophalangeal joint

N: Lateral plantar nerve from tibial nerve (S2, S3)

Question 26

Dorsal interossei (4th layer) (4 muscles – bipennate muscles)

Answer 26

O: Sides of adjacent metatarsals

I: Extensor hoods and bases of proximal phalanges of 2nd to 4th toes
	First: Medial surface of proximal phalanx of 2nd toe
	Second-fourth: Lateral surfaces of proximal phalanx of 2nd-4th toes

A: Open Chain: Abduction of 2nd to 4th toes at metatarsophalangeal joint; flexion of the metatarsalphalangeal joint and extension of the interphalangeal joint
Closed Chain: resists extension of metatarsophalangeal joints and resist flexion of interphalangeal joint

N: Lateral plantar nerve from tibial nerve (S2, S3)
1st and 2nd interossei may also have dual innervation by deep fibular nerve

Question 27

Plantar interossei (4th layer) (3 muscles – unipennate)

Answer 27

O: Medial sides of metatarsals of 3rd to 5th toes

I: extensor hoods and bases of proximal phalanges of 3rd to 5th toes on medial side

A: Open Chain: Adduction of 3rd to 5th toes at metatarsophalangeal joint; flexion of the metatarsalphalangeal joint and extension of the interphalangeal joint
Closed Chain: resists extension of metatarsophalangeal joints and resist flexion of interphalangeal joint

N: lateral plantar nerve from tibial nerve (S2, S3)