Posterior Compartment of the Leg Flashcards
Muscles
State the dual origin of the gastrocnemius.
Medial head:
From the popliteal surface of the femur just above the medial condyle.
This head is separated from the capsule of the knee joint by a bursa which may communicate with the semimembranosus bursa.
Lateral head:
From an impression on the lateral surface of the lateral condyle of the femur just above and behind the lateral epicondyle.
This head usually contains a sesamoid bone called the labella close to the lateral condyle of the femur.
The two heads are tendinous at their origin, but they expand into two fleshy bellies, which remain separate and form aponeurotic tendons which join the tendon of soleus to form the tend calcaneus.
State the insertion of gastrocnemius.
By the tendo calcaneus into the middle of the posterior surface of the calcaneus.
A bursa and some fat separate the tendo calcaneus from the smooth upper part of the posterior surface of the calcaneus.
State the nerve supply of the gastrocnemius.
By a branch for each head from the tibial (medial popliteal) nerve in the popliteal fossa.
State the actions of the gastrocnemius.
Plantar flexion of the foot.
Flexor of the knee joint.
State the origin and insertion of the plantaris.
Origin: popliteal surface of the femur just above the lateral condyle.
Insertion:
It is a small muscle which descends close to the medial side of the lateral head of gastrocnemius.
Its small and short belly gives rise to a long slender tendon which descends obliquely downwards and medially b2n the gastrocnemius and soleus.
The tendon then descends close to the medial side of the tendo calcaneus to be inserted into the posterior surface of the calcaneus.
State the nerve supply of the plantaris.
Branch from the tibial (medial popliteal) nerve in the popliteal fossa.
Describe actions of the plantaris.
Plantar flexion of the foot.
Flexion of the knee.
Applied anatomy of the plantaris.
Avulsion of the tendon of plantaris may occur during running leading to a sudden and severe pain in the lower part of the calf.
State the (continuous) origin of the soleus.
The upper 1/3 of the posterior surface of the fibula, extending up to its head.
The tendinous arch b2n the head of the fibula and the upper end of the soleal line of the tibia. This arch bridges over the posterior tibial vessels and the tibial nerve as they descend to the posterior compartment.
Soleal line of the tibia.
Middle 1/3 of the medial border of the tibia.
State the insertion of soleus.
By a strong tendon with the gastrocnemius into the tendo calcaneus.
The tendo calcaneus is inserted into the middle of the posterior surface of the calcaneus.
State the (double) nerve supply of soleus.
Superficial surface: branch from tibial (medial popliteal) nerve in the popliteal fossa.
Deep surface: a branch from the tibial (posterior tibial) nerve in the leg.
Describe the action of the soleus.
Powerful plantar flexor of the foot.
State the origin and insertion of popliteus.
Origin:
By a tendon from the anterior part of the groove on the lateral surface of the lateral condyle of the femur below the lateral epicondyle.
This origin lies inside the capsule of the knee joint (intracapsular).
Insertion:
The tendon of origin passes out through an opening in the posterolateral aspect of the capsule of the knee joint and spreads downwards and medially into a triangular fleshy muscle which is inserted into the posterior surface of the tibia above the soleal line and to the strong fascia covering popliteus muscle.
State the nerve supply of popliteus.
Branch from tibial (medial popliteal) nerve in the popliteal fossa.
The nerve to popliteus descends over the fascia covering the muscle and then hooks on the distal border of popliteus to supply the muscle through its deep surface.
Describe the actions of popliteus.
Flexion of the knee joint. At the start of flexion of the extended knee, the popliteus produces a small amount of media rotation of the leg or lateral rotation of the femur on the tibia which is referred to as “unlocking of the knee joint.”
State the origin and insertion of the flexor digitorum longus.
Origin: posterior surface of the tibia below the soleal line and medial to the vertical line.
Insertion:
It gives a tendon which descends to the lower part of the leg where it crosses superficial to (behind) the tendon of tibialis posterior from the medial to lateral side.
Then, it descends deep to the flexor retinaculum to the sole of the foot.
It is one of the contents of the 2nd layer of the sole where it divides into 4 tendons which are inserted into the bases of the terminal phalanges of the lateral 4 toes.
State the nerve supply of the flexor digitorum longus.
Tibial (posterior tibial) nerve.
Describe the actions of the flexor digitorum longus.
Flexion of the interphalangeal and metatarsophalangeal joints of the lateral 4 toes.
Plantar flexion.
It helps in inversion of the foot.
It helps in supporting the longitudinal arch of the foot.
State the origin and insertion of tibialis posterior.
Origin:
Posterior surface of the tibia below the soleal line and lateral to the vertical line.
Posterior surface of the fibula medial to the medial crest.
Interosseous membrane.
Insertion:
The muscle gives a strong tendon which descends downwards and medially where it crosses deep to the flexor digitorum longus from the lateral to medial side.
Then, it descends close to the back of the medial malleolus grooving the bone and passing deep to the flexor retinaculum.
It reaches the sole of the foot in the 4th layer where it divides into slips which are inserted into all tarsal bones except the talus and to the bases of the 2nd, 3rd and 4th metatarsal bones.
The main insertion is into the tuberosity of navicular bone.
State the nerve supply of tibialis posterior.
Tibial (posterior tibial) nerve.
