LL2 - Muscles of the leg

Question 1

What are the movements at the ankle joint?

Answer 1

dorsiflexion/plantarflexion
inversion/eversion

Question 2

What is the function (movements) of the posterior compartment of leg muscles?

Answer 2

foot inversion
ankle plantarflexion

Question 3

What are the movements of the foot?

Answer 3

flexion/extension
abduction/adduction

Question 4

What are the superficial muscles of the posterior compartment?

Answer 4

gastrocnemius
soleus
plantaris

Question 5

What are the deep muscles of the posterior compartment?

Answer 5

popliteus
tibialis posterior
flexor digitorum longus
flexor hallucis longus

Question 6

common innervation of muscles of the posterior compartment of the leg? (superficial and deep layers)

Answer 6

tibial nerve

Question 7

gastrocnemius - origin (medial & lateral heads)? insertion? action? innervation?

Answer 7

origin:
- medial head = medial femoral condyle
- lateral head = lateral femoral condyle

insertion:
- Achilles tendon (calcaneal tuberosity)

action:
- knee flexion
- ankle plantarflexion (only when knee is extended)

innervation: tibial nerve

Question 8

soleus - origin? insertion? action? innervation?

Answer 8

origin - posterior tibia & head of posterior fibula

insertion: Achilles tendon (calcaneal tuberosity)

action:
- knee flexion
- ankle plantarflexion

innervation: tibial nerve

Question 9

plantaris - origin? insertion? action? innervation?

Answer 9

origin: lateral supracondylar line (femur)

insertion: Achilles tendon (calcaneal tuberosity)

action:
- weak knee flexion
- weak ankle plantarflexion

innervation: tibial nerve

Question 10

what muscles are referred to as the triceps surae? why?

Answer 10

gastrocnemius & soleus - have 3 heads between them (2 from gastrocnemius, 1 from soleus)

Question 11

common insertion point for the muscles of the posterior superficial leg compartment?

Answer 11

Achilles tendon (calcaneal tuberosity)

Question 12

popliteus - origin? insertion? action? innervation?

Answer 12

origin: lateral femoral condyle

insertion: posterior proximal tibia

action:
- unlocks knee from extended position by laterally rotating femur = allows for knee flexion

innervation: tibial nerve

Question 13

tibialis posterior - origin? insertion? action? innervation?

Answer 13

origin: posterior tibia, fibula & interosseus membrane

insertion: navicular & medial cuneiform

action:
- foot inversion
- ankle plantarflexion
- supports medial longitudinal arch

innervation: tibial nerve

Question 14

flexor digitorum longus - origin? insertion? action? innervation?

Answer 14

origin: posterior tibia

insertion: distal phalanx of lateral 4 toes

action:
- ankle plantarflexion
- flexion of lateral 4 toes

innervation: tibial nerve

Question 15

flexor hallucis longus - origin? insertion? action? innervation?

Answer 15

origin: posterior fibula & interosseus membrane

insertion: distal phalanx of great toe

action:
- ankle plantarflexion
- flexion of great toe

innervation: tibial nerve

Question 16

what forms the tarsal tunnel? - roof, anterior & posterior boundaries

Answer 16

roof - flexor retinaculum
anterior - distal tibia/ medial malleolus
posterior - Achilles tendon

Question 17

what are the contents of the tarsal tunnel (anterior to posterior)? (Tom, Dick and Very Nervous Harry)

Answer 17

Tom - tibialis posterior
Dick - flexor digitorum longus
And - posterior tibial artery
Very - posterior tibial vein
Nervous - tibial nerve
Harry - flexor hallucis longus

Question 18

What is tarsal tunnel syndrome?

Answer 18

compression of the tibial nerve within the tarsal tunnel

Question 19

symptoms of tarsal tunnel syndrome? (2)

Answer 19

numbness/tingling in sole of foot
weakness/dysfunction in foot movements

Question 20

Which muscles are in the anterior compartment of the leg? (4)

Answer 20

tibialis anterior
extensor digitorum longus
extensor hallucis longus
fibularis tertius

Question 21

What is the function of the anterior compartment of the leg?

Answer 21

ankle dorsiflexion

Question 22

Which muscles are in the lateral compartment of the leg? (2)

Answer 22

fibularis longus
fibularis brevis

Question 23

what is the function of the lateral compartment of the leg?

Answer 23

ankle eversion
ankle plantarflexion

Question 24

what is the nerve that commonly innervates the anterior compartment of the leg?

Answer 24

deep fibular nerve

Question 25

what is the nerve that commonly innervates the lateral compartment of the leg?

Answer 25

superficial fibular nerve

Question 26

common actions of leg muscles of the lateral compartment? (3)

Answer 26

foot eversion (weak) ankle plantarflexion support arches of the foot

Question 27

fibularis longus - origin? insertion? action? innervation?

Answer 27

origin: superior 2/3 of fibula insertion: base of 1st metatarsal & medial cuneiform action: - ankle plantarflexion - foot eversion - supports arches of the foot innervation: deep fibular nerve

Question 28

fibularis brevis - origin? insertion? action? innervation?

Answer 28

origin: inferior 1/3 of fibula insertion: base of 5th metatarsal action: - ankle plantarflexion - foot eversion - supports arches of the foot innervation: deep fibular nerve

Question 29

tibialis anterior - origin? insertion? action? innervation?

Answer 29

origin: tibia & interosseus membrane insertion: medial cuneiform & base of 1st metatarsal action: ankle dorsiflexion, foot inversion innervation: deep fibular nerve

Question 30

fibularis tertius - origin? insertion? action? innervation?

Answer 30

origin: distal fibula insertion: base of 5th metatarsal action: ankle dorsiflexion & foot eversion innervation: deep fibular nerve

Question 31

extensor digitorum longus - origin? insertion? action? innervation?

Answer 31

origin: fibula & lateral tibial condyle insertion: middle & distal phalanges of lateral 4 toes action: ankle dorsiflexion & extends lateral 4 toes innervation: deep fibular nerve

Question 32

extensor hallucis longus - origin? insertion? action? innervation?

Answer 32

origin: fibula & interosseus membrane insertion: hallux distal phalanx action: ankle dorsiflexion & extends great toe innervation: deep fibular nerve

Question 33

which leg muscles (2) are involved in foot inversion?

Answer 33

tibialis anterior tibialis posterior

Question 34

which leg muscles/compartment are involved in ankle dorsiflexion? what nerve are they innervated by?

Answer 34

anterior leg compartment - tibialis anterior - fibularis tertius - extensor digitorum longus - extensor hallucis longus innervated by deep fibular nerve

Question 35

which muscles cause ankle dorsiflexion?

Answer 35

posterior compartment muscles (not popliteus) - (superficial) gastrocnemius, soleus, plantaris - (deep) tibialis posterior, flexor digitorum longus & flexor hallucis longus lateral compartment muscles: - fibularis longus & brevis

Question 36

which muscles cause foot eversion? (3)

Answer 36

fibularis longus fibularis brevis fibularis tertius

Question 37

A runner complains of numbness in the sole of the foot and pain worsened by prolonged standing. Which structure is most likely compressing the tibial nerve? A. Popliteal fossa B. Fibular retinaculum C. Tarsal tunnel D. Extensor retinaculum

Answer 37

C. Tarsal tunnel

Question 38

A patient with foot eversion weakness and sensory loss over the dorsum of the foot likely has an injury to which nerve? A. Deep fibular B. Tibial C. Sural D. Superficial fibular

Answer 38

D. Superficial fibular - innervates lateral compartment (fibularis longus & brevis) - supplies foot eversion and supplies foot dorsum

Question 39

Which muscle plays no role in ankle plantarflexion? A. Plantaris B. Soleus C. Popliteus D. Flexor digitorum longus

Answer 39

C. Popliteus - just laterally rotates femur to unlock knee for knee flexion

Question 40

During surgical exploration of the leg, a long thin tendon is found coursing between gastrocnemius and soleus. It is likely from a muscle that: A. Strongly plantarflexes the foot B. Flexes the big toe C. Has no functional significance D. Inverts the foot

Answer 40

**C. Has no functional significance** - *plantaris* runs between gastrocnemius & soleus; has minimal contribution to ankle plantarflexion and inversion

Question 41

Which of the following actions would be most affected in a lesion of the tibial nerve in the popliteal fossa? A. Dorsiflexion B. Eversion C. Toe extension D. Plantarflexion

Answer 41

D. Plantarflexion - tibial nerve supplies posterior compartment (foot inversion & ankle plantarflexion)

Question 41

A patient has weakness in toe flexion, loss of sensation on the sole, and an intact Achilles reflex. Where is the lesion most likely? A. Tibial nerve above popliteal fossa B. Tibial nerve in the tarsal tunnel C. Common fibular nerve at fibular neck D. Deep fibular nerve in anterior compartment

Answer 41

**B. Tibial nerve in the tarsal tunnel** - tarsal tunnel syndrome – sensory and motor to sole affected, but Achilles reflex spared (soleus/gastrocnemius innervation is proximal)

Question 41

Which of the following muscles contributes to both foot eversion and ankle dorsiflexion? A. Tibialis anterior B. Fibularis brevis C. Extensor digitorum longus D. Fibularis tertius

Answer 41

**D. Fibularis tertius** - anterior compartment; dorsiflexion + slight eversion.

Question 42

A patient is unable to invert the foot but retains dorsiflexion and plantarflexion. Which muscle is most likely affected? A. Fibularis longus B. Tibialis anterior C. Extensor digitorum longus D. Flexor digitorum longus

Answer 42

B. Tibialis anterior - key invertor of foot; loss of inversion with retained dorsiflexion = TA injury

Question 43

Which muscle tendon passes deep to the flexor retinaculum, is the most anterior in the tarsal tunnel, and is primarily responsible for foot inversion? A. Flexor hallucis longus B. Tibialis posterior C. Flexor digitorum longus D. Tibialis anterior

Answer 43

B. Tibialis posterior

Question 44

Which posterior leg muscle contributes to knee flexion but is ineffective at plantarflexion when the knee is flexed? A. Soleus B. Gastrocnemius C. Plantaris D. Tibialis posterior

Answer 44

B. Gastrocnemius - loses plantarflexion strength when the knee is flexed as it crosses both joints

Question 45

Damage to the deep fibular nerve will most likely cause which deficit? A. Inability to plantarflex the foot B. Foot drop and sensory loss between first two toes C. Loss of eversion and numbness over lateral leg D. Inability to flex toes

Answer 45

**B. Foot drop and sensory loss between first two toes** - DF nerve innervates anterior compartment (dorsiflexors) (loss of dorsiflexion = foot drop) & sensory loss in first webspace

Question 46

A structure is found deep to both gastrocnemius and soleus and assists in unlocking the knee joint during flexion. What is it? A. Plantaris B. Tibialis posterior C. Popliteus D. Flexor hallucis longus

Answer 46

C. Popliteus

Question 47

A lesion of the superficial fibular nerve will result in weakness of: A. Foot inversion B. Foot dorsiflexion C. Foot eversion D. Toe extension

Answer 47

C. Foot eversion - innervates lateral compartment (fibularis brevis & longus)

Question 48

Deep fibular nerve innervation is associated with what ankle movement?

Answer 48

ankle dorsiflexion (anterior compartment)

Question 49

Which muscle contributes to toe flexion, runs in the posterior deep compartment, and can be tested by flexion of the great toe? A. Flexor hallucis longus B. Flexor digitorum longus C. Extensor hallucis longus D. Plantaris

Answer 49

A. Flexor hallucis longus

Question 50

The triceps surae muscle group has a common insertion into the: A. Navicular bone B. Base of the 1st metatarsal C. Calcaneal tendon D. Medial malleolus

Answer 50

C. Calcaneal tendon - triceps surae = gastrocnemius (2 heads) + soleus

Question 51

Injury to the common fibular nerve near the neck of fibula would affect which action most severely? A. Toe flexion B. Foot inversion C. Foot eversion and dorsiflexion D. Knee extension

Answer 51

C. Foot eversion and dorsiflexion - splits into deep + superficial fibular branches = supply anterior and lateral compartments

Question 52

what is the flexor retinaculum of the foot?

Answer 52

fibrous band on the medial side of the ankle - from medial malleolus (tibia) to calcaneus forms roof of tarsal runnel; holds down tendons & nv. structures passing from leg into foot

Question 53

what does the flexor retinaculum do during plantarflexion?

Answer 53

prevents bowing out of tendons during plantarflexion

Question 54

what is the popliteal fossa?

Answer 54

**diamond-shaped space** located on the **posterior aspect of the knee** - passageway for neurovascular structures to travel from thigh to leg & foot

Question 55

What are the boundaries of the popliteal fossa? (superolateral, superomedial, inferolateral, inferomedial, roof and floor)

Answer 55

superomedial = semitendinosus & semimembranosus superolateral = biceps femoris inferomedial & lateral = heads of gastrocnemius roof = skin & fascia floor = posterior femur, popliteus muscle, joint capsule of knee

Question 56

what muscle forms the inferolateral and medial borders of the popliteal fossa?

Answer 56

gastrocnemius - medial & lateral heads

Question 57

what muscles form the superomedial & superolateral boundaries of the popliteal fossa?

Answer 57

semitendinosus & semimembranosus = superomedial biceps femoris = superolateral

Question 58

What happens to the sciatic nerve in the popliteal fossa?

Answer 58

splits into the tibial nerve and common fibular nerve — usually in the upper part of the fossa

Question 59

What is the function of the popliteus muscle, and where is it located?

Answer 59

function: laterally rotates femur to unlock knee for knee flexion location: floor of popliteal fossa (runs from lateral femoral condyle to proximal posterior tibia)

Question 60

Why can the popliteal pulse be difficult to palpate?

Answer 60

popliteal artery lies deep - surrounded by adipose tissue and other structures

Question 61

Why is the common fibular nerve prone to injury?

Answer 61

runs superficially around the neck of the fibula (& bifurcates into superficial and deep branches here) - easily injured by trauma, plaster casts, or prolonged pressure

Question 62

Injury to the common fibular nerve causes which clinical features?

Answer 62

- foot drop (loss of dorsiflexion - affects innervation to anterior compartment) - loss of eversion - sensory loss over dorsum of foot and lateral leg

Question 63

What artery enters the popliteal fossa, and through what structure?

Answer 63

**femoral artery** - enters via adductor hiatus into popliteal fossa - becomes popliteal artery