posterior compartment of the leg Flashcards
What seperates the deep and superifical posterior compartment?
The deep transverse intermuscular septum
What are the contents of the posterior compartment? what actions predominate?
knee flexion, ALL ankle plantarflexors, foot invertors, digit plantarflexors
The posterior compartment is innervated by what nerve?
tibial nerve
What are the superficial muscles of the posterior compartment?
GPS Gastrocnemious , soleus, plantaris
What are highlights of the gastrocnemius?
medial head tends to be larger than the lateral head, either head may contain a fabella/ sesamoid head- more common in LATERAL head. ALSO A KNEE FLEXOR, it is not an efficient ankle plantarflexor when knee is flexed.
What are some highlights of the soleus?
can plantarflex the ankle regardless of knee posture.
What are some highlights of plantaris?
Plantaris plays a minor role and can be removed for grafting
What are the deep muscles of the posterior compartment?
popliteus, FHL , FDL, and TP
What are some highlights of the popliteus muscle?
Only muscle of the posterior compt that does not cross the ankle, during knee flexion may pull lateral meniscus posteriorly. When knee is partially flexed, may assist PCL in checking ant displacement.
What three muscles are inferior to popliteus and deep to soleus?
FHL (lateral) FDL (M) TP
At foot flat, how do post compa muscles act?
eccentric contraction of triceps surae moderates ankle dorsiflexion. Tp, FHL and FDL support medial longitudinal arch as foot pronates.
At midstance, how do post comp muscles act?
triceps surae controls ankle dorsiflexon
At terminal stance, how do post. comp muscles act?
concentric contrations of triceps surae producing heel-up. TP, FHL, and FDL support medial longitudinal arch and stabilize forefoot for propulsion during toe-off
GRF line at toe off- What muscle groups will be recruited at each joint to offset the effect of ground reaction force and to keep the body moving forward?
at hip- hip flexors, at knee- knee extensors, at ankle- ankle plantarflexors
What is apropulsive or calcaneal gait?
Weakness of the ankle plantarflexors can result in insufficient propulsion. There will be no toe-off, but the entire foot will leave the ground at once. Patient will often rotate the foot as far externally as possible to allow for push-off to occur at midfoot.
At the lateral edge of the achilles tendon, what two structures run within the superficial fascia
smalls saphenous vein and sural nerve
S2 dermatome
posterior femoral cutaneous
L5 dermatome
Lateral sural cutaneous nerve and medial sural cutaneous nerve, superficial fibular , sural
S1 dermatome
Sural nerve, some medial sural cutaneous
How is the posterior compartment seperated from the anterior and lateral comaprtment?
tibia, interosseus mem, fibula, post intermuscular septum
The superficial posterior compartment is seperated from the deep posterior compartment via
deep transverse intermuscular septum
posterior muscles of the posterior compartment : inn, blood, fxn
tibial nerve, branches off popliteal artery, post tib, fibular artery, All except popliteus plantarflex the ankle and most contribute to inversion of the foot.
what muscles make up the superficial post compartment or triceps surae?
plantaris, gastrocnemius, soleus
What is the origin, insertion, and action of gastrocnemius?
O: medial head- pop surface of femur, super to med fem condyle. Lat head: lat aspect of lat femoral condyle fibers for both heads also arise from knee joint capsule
I: posterior surface of calcaneus via calcaneal tendon (achilles tendon) A: flexes leg at knee joint, plantarflexes ankle when knee is extended, contributes to inversion of foot