Posterior Compartment in Leg Flashcards
triceps surae
- gastrocnemius and soleus
- three-headed
- elevates heel, depresses forefoot
- generates 93% plantarflexion force
posterior compartment of leg
- largest of 3 leg compartments
- plantarflexors
- transverse intermuscular septum divides posterior compartment into superficial and deep muscles
- innervated by tibial nerve
- posterior tibial and fibular vessels
superficial posterior leg muscles
- gastrocnemius
- soleus
- plantaris
Gastrocnemius
- most superficial muscle
- inferolateral and inferomedial borders of popliteal fossa
- capable of acting on both the knee and ankle joints
- functions most effectively when the knee is extended and is maximally activated when knee extension is combined with dorsiflexion
Soleus
- “workhorse” of plantarflexion
- has tendinous arch of soleus – popliteal artery and tibial nerve exit the popliteal fossa through this arch, popliteal artery bifurcates into anterior and posterior tibial arteries
- palpated on sides of gastrocnemius when standing on tiptoes
- acts alone when knee is flexed
- antigravity muscle
Plantaris
- absent in 5-10% of people
- can be removed for grafting (ex: during reconstructive surgery for tendons of hand)
Deep muscles of posterior leg
- popliteus
- flexsor hallicus longus
- flexor digitorum longus
- tibialis posterior
Subcutaneous calcaneal bursa
between skin and calcaneal tendon
bursa of calcaneal tendon
- deep
- between calcaneal tendon and calcaneous
Tibial Nerve (L4,L5, and S1-S3)
- larger of two terminal branches of sciatic nerve
- runs through popliteal fossa with the popliteal artery and vein passing between heads of gastrocnemius
- supplies all leg muscles in posterior compartment of leg
- divides into the medial and lateral plantar nerves
Sural Nerve
a branch of the tibial nerve, the medial sural cutaneous nerve, unites with the communicating branch of the common fibular nerve to form the sural nerve
- this nerve supplies the skin of the lateral and posterior part of the inferior third of the leg and lateral side of the foot
posterior tibial artery
- larger terminal branch of popliteal artery
- supplies posterior compartment of leg to foot
- begins at distal border of popliteus, goes deep to tendinous arch of the soleus
- gives off fibular artery (largest branch)
- divides into medial and lateral plantar arteries
fibular artery
- gives rise to the nutrient artery of the fibula
- perforating branch pierces interosseous membrane and passes to dorsum of foot
Structures passing posterior to medial malleolus
“Tom Dick A Very Nervous Harry”
- Tibialis Posterior
- Flexor Digitorum Longus
- Posterior Tibial Artery
- Vein
- Tibial Nerve
- Flexor Hallicus Longus
Gastrocnemius - Origin
- Lateral Head – lateral aspect of lateral condyle of femur
- Medial Head – popliteal surface of femur, superior to medial condyle
Gastrocnemius - Insertion
posterior surface of calcaneus via calcaneal tendon
Gastrocnemius - Innervation
Tibial Nerve (S1, S2)
Gastrocnemius - Action
- plantarflexes ankle when knee is extended
- raises heel during walking
- flexes leg at knee joint
Soleus - Origin
- posterior aspect of head of fibula
- superior quarter of posterior surface of fibula
- soleal line
- medial border of tibia
Soleus - Insertion
- posterior surface of calcaneous via calcaneal tendon
Soleus - Innervation
Tibial Nerve (S1, S2)
Soleus - Action
- plantarflexes ankle
- steadies leg on foot
Plantaris - Origin
- inferior end of lateral supracondylar line of femur
- oblique popliteal ligament
Plantaris - Insertion
posterior surface of calcaneus via calcaneal tendon
Plantaris - Innervation
Tibial Nerve (S1,S2)
Plantaris - Action
weakly assists gastrocnemius in plantarflexing ankle
Popliteus - Origin
- lateral surface of lateral condyle of femur
- lateral meniscus
Popliteus - Insertion
- posterior surface of tibia superior to soleal line
Popliteus - Innervation
Tibial Nerve (L4, L5, S1)
Popliteus - Action
- weakly flexes knee and unlocks it by laterally rotating femur on fixed tibia, or medially rotating tibia of unplanted limb
Flexor Hallicus Longus - Origin
- inferior 2/3 of posterior surface of fibula
- inferior part of interosseous membrane
FHL - Insertion
base of distal phalanx of great toe (hallux)
FHL - Innervation
Tibial Nerve (L2, L3)
FHL - Action
- flexes great toe at all joints
- weakly plantarflexes ankle
- supports medial longitudinal arch of foot
Flexor Digitorum Longus - Origin
- medial part of posterior surface of tibia inferior to soleal line by broad tendon to fibula
FDL - Insertion
bases of distal phalanxes of lateral 4 digits
FDL - Innervation
Tibial Nerve (S2, S3)
FDL - Action
- flexes lateral four digits
- plantarflexes ankle
- supports longitudinal arch of foot
Tibialis Posterior - Origin
- interosseous membrane
- posterior surface of tibia inferior to soleal line
- posterior surface of fibula
Tibialis Posterior - Insertion
- primarily to tuberosity of navicular
- to cuneiforms, cuboid, and bases of 2nd-4th metatarsals
Tibialis Posterior - Innervation
Tibial Nerve (L4, L5)
Tibialis Posterior - Action
- plantarflexes ankle
- inverts foot
- supports medial longitudinal arch of foot
