Lecture 11 - Muscles Of The Lower Leg Flashcards
What type of movements are in the lower leg?
- ankle; Talocrural (true ankle joint): dorsiflexion/plantarflexion
- Subtalar joint: inversion/eversion
- foot: flexion/extension & abduction/adduction
What are the 3 compartments of the lower leg?
- anterior
- lateral
- posterior
How many muscles are in the anterior compartment of the lower leg? What are they?
- 4
- Tibialis anterior
- extensor Hallucis longus
- extensor digitorum longus
- Peroneus tertius
What is the origin/insertion/Innervation/main action of the Tibialis anterior ?
- O: Lateral condyle & lateral surface of tibia (upper half) & the interosseous membrane
- I: 1st cuneiform & base of the 1st metatarsal (medial & inferior surfaces)
- Inn: Deep perineal nerve
- MA: Talocrural dorsi flexion & Sub-talar inversion
What is the origin/insertion/Innervation/main action of the extensor Hallucis longus?
- O: Mid-portion of the medial fibula & interosseous membrane
- I: Distal phalanx of big toe
- Inn: Deep peroneal nerve
- MA: Extends the big toe & Dorsiflexion
What is the origin/insertion/Innervation/main action of the extensor digitorum longus?
- O: Lateral tibial condyle, interosseous membrane, & medial fibula
- I: Distal phalanges of toes 2-5
- Inn: Deep peroneal nerve
- MA: Extension of toes 2-5 & Dorsiflexion
What is the origin/insertion/Innervation/main action of the Peroneus tertius?
- O: Lower medial fibula
- I: Base of the 5th metatarsal
- Inn: Deep peroneal nerve
- MA: Eversion & Dorsiflexion
What is the lateral compartment of the lower leg?
- Small compartment on the lateral side of the fibula
- Evertors of the sub-talar joint
- Tendons run behind the lateral malleolus
How many muscles are in the lateral compartment of the lower leg? What are they?
- 2
- Peroneus longus
- Peroneus brevis
What is the origin/insertion/Innervation/main action of the Peroneus longus?
- O: Head & upper 2/3 lateral fibula
- I: 1st cuneiform & the base of the 1st metatarsal (on the plantar aspect of the foot)
- Inn: Superficial peroneal nerve
- MA: Subtalar eversion
What is the origin/insertion/Innervation/main action of the Peroneus brevis?
- O: Lower 2/3 lateral fibula
- I: Base of 5th metatarsal
- Inn: Superficial peroneal nerve
- MA: Subtalar eversion
What is the posterior compartment of the lower leg?
- made up of a superficial layer & a deep layer
What is the superficial layer of the posterior compartment of the lower leg?
- forms the bulk of the calf muscle
- Powerful anti-gravity muscles
- All converge as the Achilles tendon & the to the calcaneus
- There are 2 protective bursal sacs; Achilles tendon & retro-calcaneal bursa
How many muscles are in the superficial layer of the posterior compartment of the lower leg? What are they?
- 3
- gastrocnemius
- soleus
- plantaris
What is the origin/insertion/Innervation/main action of the gastrocnemius?
- O: Medial & lateral femoral condyles
- I: Posterior calcaneus
- Inn: Tibial nerve
- MA: Ankle plantar flexion or knee flexion (can’t do both at same time) & Propelling force in walking, running, & leaping
What is the origin/insertion/Innervation/main action of the soleus?
- O: Posterior head & shaft of the fibula, across the interosseous membrane
- I: Posterior calcaneus
- Inn: Tibial nerve
- MA: Ankle plantar flexion
What is the origin/insertion/Innervation/main action of the plantaris?
- O: Just above the lateral femoral condyle
- I: Posterior calcaneus
- Inn: Tibial nerve
- MA: Knee flexion or plantar flexion
What is the deep layer of the posterior compartment of the lower leg?
- Tendons run posterior to the medial malleolus
- Remember them: (“Tom, Dick, & Harry, Tom = Tibialis posterior, Dick = flexor digitorum longus, Harry = flexor Hallucis longus)
How many muscles are in the deep layer of the posterior compartment of the lower leg? What are they?
- 3
- Tibialis posterior
- flexor Hallucis longus
- flexor digitorum longus
What is the origin/insertion/Innervation/main action of the Tibialis posterior ?
- O: Interosseous membrane & adjacent surfaces of the posterior tibia & fibula
- I: Navicular & 1st cuneiform
- Inn: Tibial nerve
- MA: Sub-talar inversion
What is the origin/insertion/Innervation/main action of the flexor Hallucis longus?
- O: Inferior posterior fibula
- I: Base of distal phalanx of big toe
- Inn: Tibial nerve
- MA: Flexion of big toe
What is the origin/insertion/Innervation/main action of the flexor digitorum longus?
- O: Posteromedial tibia
- I: Bases of the distal phalanges 2-5
- Inn: Tibial nerve
- MA: Flexion of toes 2-5
What is the origin/insertion/Innervation/main action of the popliteus?
- O: Lateral femoral condyle
- I: Posterior proximal tibia
- Inn: Tibial nerve
- MA: Lateral rotation of the femur (if tibia is fixed): unlocks the screw home mechanism
What is the popliteal fossa?
- Diamond shape
- Contains the popliteal artery/vein, small saphenous vein, tibial nerve, common fibular nerve, & popliteal lymph nodes
- Branching of the sciatic nerve
What is the intrinsic muscle on the dorsal aspect of the foot?
- extensor digitorum brevis
What are the 2 intrinsic muscles on the plantar side of the foot?
- flexor digitorum brevis
- flexor Hallucis brevis
What do the intrinsic muscles of the foot do?
- act to modify actions of longer tendons as well as generate fine movements of the toes
