Posterior Compartment Leg Muscles (Quiz/Exam 3) Flashcards
What are the 3 superficial posterior compartment muscles of the leg?
1) gastrocnemius
2) soleus
3) plantaris
There are 3 superficial posterior compartment muscles of the leg: gastrocnemius, soleus, and plantaris. They all do….
plantar flexion
What is the origin/proximal attachment for the lateral head of the gastrocnemius?
lateral aspect of the lateral condyle of the femur
What is the origin/proximal attachment of the medial head of the gastrocnemius?
popliteal surface of the femur, superior to medial condyle
What is the insertion/distal attachment for the gastrocnemius?
posterior surface of calcaneus via calcaneal tendon
What innervates the gastrocnemius?
tibial n.
What are the actions of the gastrocnemius?
-plantar flexes ankle when knee is extended
-raises heel during walking
-flexes leg at the knee joint
note: it is not active when the knee is flexed, it needs to be extended to be able to plantar flex
Is the gastrocnemius a type 1 or 2 muscle? What does this mean?
type 2
-fast twitch muscle /white muscle
-produces rapid movements during running and jumping
Is the soleus a type 1 or type 2 muscle? What does this mean?
type 1
-red muscle
-fatigue resistant muscle
-slow twitch muscle
-capable of sustained contraction
-good for strolling and standing
What are the origins of the soleus?
test q
-posterior aspect of the head of the fibula
-superior quarter of posterior surface of fibula soleal line
-medial border of tibia
What is the insertion of the soleus?
posterior surface of calcaneus via calcaneal tendon
What innervates the soleus?
tibial n.
What are the actions of the soleus?
-plantar flexes ankle independent of the position of the knees
-steadies leg on foot
Which muscle is absent in 5-10% of people?
test q
plantaris
What is the origin of the plantaris?
-inferior end of lateral supracondylar line of femur
-oblique popliteal ligament
What is the insertion/distal attachment of the plantaris?
posterior surface of calcaneus via calcaneal tendon
What innervates the plantaris?
tibial n.
What are the actions of the plantaris?
weakly assists gastrocnemius in plantar flexing ankle
What is the origin/proximal attachment of the popliteus?
lateral surface of the lateral condyle of the femur and lateral meniscus
What is the insertion/distal attachment for the popliteus?
posterior surface of the tibia, superior to the soleal line
What innervates the popliteus?
tibial n.
What are the actions of the popliteus?
-weakly flexes knee and unlocks it by rotating femur on a fixed tibia
-medially rotates tibia of unplanted limb
What is the origin/proximal attachment for the flexor hallucis longus?
inferior 2/3 of posterior surface of fibula and inferior part of interosseous membrane
What is the insertion/distal attachment for the flexor hallucis longus?
base of distal phalanx of the great toe
What innervates the flexor hallucis longus?
tibial n.
What are the actions of the flexor hallucis longus?
-flexes great toe at all joints
-weakly plantar flexes ankle
-supports medial longitudinal arch of the foot
What is the origin/proximal attachment of the flexor digitorum longus?
medial part of posterior surface of the tibia inferior to the soleal line by a broad tendon to the fibula
What is the insertion/distal attachment for the flexor digitorum longus?
bases of distal phalanges of lateral 4 digits
What innervates the flexor digitorum longus?
tibial n.
What are the actions of the flexor digitorum longus?
-flexes lateral 4 digits
-plantar flexes ankle
-supports longitudinal arch of foot
What is the origin/proximal attachment for the tibialis posterior?
-interosseous membrane
-posterior surface of tibia inferior to soleal line
-posterior surface of fibula
What is the insertion/distal attachment for the tibialis posterior?
-tuberosity of navicular, cuneiform, and cuboid
-bases of 2nd, 3rd, and 4th metatarsals
What innervates the tibialis posterior?
tibial n.
What are the actions of the tibialis posterior?
plantar flexes ankle and inverts the foot (its a strong muscle)
