Muscle of the Lower Limb Pt 2

Question 1

Anterior compartment of leg

Answer 1

Tibialis anterior

Extensor digitorum longus

Extensor hallucis longus

Fibularis tertius

All anterior supplied by deep Fibular nerve

Question 2

Tibialis anterior

Answer 2

Proximal: lateral condyle and superior half of lateral tibia and interosseous membrane

Distal: medial and inferior surface of medial cuneiform and base of 1st metatarsal

Innervation: deep fibular nerve

Action: dorsiflexes ankle; inversion; support medial longitudinal arch

Question 3

Extensor hallucis longus

Answer 3

Proximal: middle part of anterior surface of fibula and IM

Distal: base of distal phalanx of great toe (hallux)

Innervation: deep fibular nerve

Action: extends great toe, dorsiflexes ankle

Question 4

Extensor digitorum longus

Answer 4

Proximal: lateral condyle of tibia and superior 2/3 of fibula and IM

Distal: middle and distal phalanges of lateral 4 digits via extensor expansion

Innervation: deep fibular nerve

Action: extends lateral 4 digits; dorsiflexes ankle

Question 5

Fibularis tertius

Answer 5

Small muscle; not always present

Proximal: inferior 1/3 of anterior surface of fibula and IM

Distal: dorsum of base of 5th metatarsal

Innervation: deep fibular nerve

Action: dorsiflexes ankle; aids in eversion of foot

Question 6

Lateral compartment of leg “evertor compartment”

Answer 6

Fibularis longus

Fibularis brevis

Lateral compartment supplied by superficial fibular nerve

Question 7

Fibularis longus

Answer 7

Proximal: head and superior 2/3 of lateral surface of fibula

Distal: base of 1st metatarsal and medial cuneiform

Innervation: superficial fibular nerve

Action: everts foot; plantarflexes ankle; supports transverse arch

Question 8

Fibularis brevis

Answer 8

Proximal: middle part of lateral surface of fibula

Distal: base of 5th metatarsal

Innervation: superficial fibular nerve

Action: everts foot; plantarflexes ankle

Question 9

Posterior compartment of leg (superficial)

Answer 9

Gastrocnemius

Soleus

Plantaris

Question 10

Gastrocnemius

Answer 10

Proximal: lateral head- from lateral condyle of femur; medial head- popliteal surface, superior to medial condyle

Distal: posterior calcaneus vial calcaneal (Achilles) tendon

Innervation: tibial nerve

Action: plantarflexes ankle (standing on tiptoe), raise heel during walking, leg flexion

Question 11

Soleus

Answer 11

Broad flat muscle deep to gastrocnemius

Proximal: posterior aspect of head of fibula, superior 1/4 of posterior surface of fibula, soleal line, medial border of tibia

Distal: posterior calcaneus via calcaneal tendon

Innervation: tibial nerve

Action: plantarflexes ankle, steadies leg on foot; important postural muscle during walking, running and dancing ‘antigravity muscle’

Question 12

Plantaris

Answer 12

Proximal: inferior end of lateral supracondylar line of femur and oblique popliteal ligament

Distal: posterior calcaneus via calcaneal tendon

Innervation: tibial nerve

Action: weakly assists gastrocnemius in plantarflexing ankle

Question 13

Posterior compartment of leg (deep)

Answer 13

Popliteus

Flexor hallucis longus

Flexor digitorum longus

Tibialis posterior

Question 14

Popliteus

Answer 14

(Key if knee)

Proximal: lateral surface of lateral condyle of femur and lateral meniscus

Distal: posterior surface of tibia superior to soleal line

Innervation: tibial nerve

Action: weakly flexes knee and unlocks it by laterally rotating femur on flexed tibia, or medial rotating tibia of unplanted limb

Makes floor of popliteal fossa

Question 15

Flexor hallucis longus

Answer 15

Proximal: inferior 2/3 of posterior fibula and inferior part of IM

Distal: tendon runs under the foot of base of distal phalanx of great toe

Innervation: tibial nerve

Action: flexes great toe at all joints “push-off” muscle during walking

Question 16

Flexor digitorum longus

Answer 16

Proximal: medial part of posterior surface of tibia inferior to soleal line and broad tendon to fibula

Distal: base of distal phalanges of lateral 4 digits. Tendon runs behind medial malleolus

Innervation: tibial nerve

Action: flexes lateral 4 digits, plantarflexes ankle, help foot “grip” ground, support longitudinal arch

Question 17

Tibialis posterior

Answer 17

Deepest muscle

Proximal: IM, posterior surface of tibia inferior to soleal line, and posterior surface of fibula

Distal: navicular tuberosity, cubeiforms, cuboid and bases of 2nd to 4th metatarsals

Innervation: tibial nerve

Action: plantarflexes ankle, invert foot; support medial longitudinal arch

Question 18

Popliteal fossa boundaries

Answer 18

1. superolaterlly: biceps femoris
2. Superomedially: semimembranosus & semitendinosus
   3: inferolaterally: lateral head of gastrocnemius
3. Inferomedially: medial head of gastrocnemius
4. Roof: skin and popliteal fascia
5. Floor: femur, capsule of knee joint and fascia covering popliteus muscle

Question 19

Popliteal fossa contents

Answer 19

1. Small saphenous vein
2. Popliteal artery and vein
3. Tibial and common fibular nerve
4. Posterior cutaneous nerve of thigh
5. Popliteal lymph nodes, lymphatics, fat