Posterior Compartment of the Leg (Back of Leg) Flashcards
State two nerves that supply the skin of the lateral one third of the posterior leg and state their root values.
- Lateral cutaneous sural nerve: L4, 5, S1
- Sural communicating nerve: L5, S1, 2
- [Diagram]
State two nerves that supply the skin of the middle one third of the posterior leg and state their root values.
- Sural nerve (L5, S1, 2)
- Posterior cutaneous nerve of thigh (S1, 2, 3)
- [Diagram]
State two nerves that supply the skin of the medial one third of the posterior leg and state their root values.
- Saphenous nerve (L3, 4)
- Posterior division of the medial cutaneous nerve of the thigh (L2, 3)
Identify the nerve that supplies the skin of the heel and the adjoining medial side of the sole of the foot.
medial calcaneal branch of the tibial nerve
State the attachments of the flexor retinaculum.
Superiorly: posterior border and tip of the medial malleolus
Inferiorly: medial process of the calcaneal tuberosity
Name all the structures that pass deep to the flexor retinaculum in order from medial to lateral.
- Tendon of tibialis posterior
- Tendon of flexor digitorum longus
- Posterior tibial artery and its branches
- Posterior tibial nerve and its terminal branches
- Tendon of flexor hallucis longus
“The Doctors Are Not Here”
Note:
Some authorities refer to the deep peroneal nerve as anterior tibial nerve.
Describe the boundaries of the posterior compartment of the leg.
Anteriorly: posterior surfaces of the tibia, fibula, interosseous membrane, and posterior intermuscular septum [there’s no medial and lateral intermuscular septae!]
Posteriorly: Deep fascia of the leg extending from the medial border of the tibia to the posterior intermuscular septum
[Diagram]
Describe the attachments of the deep transverse septum of the posterior compartment of the leg.
Medially: proximal part of the soleal line and vertical ridge on the posterior surface of the tibia
Laterally: medial crest of the fibula
Describe the origin of gastrocnemius muscle.
Medial head: popliteal surface of the femur and adjoining posterosuperior aspect of the medial condyle of the femur
Lateral head: lateral surface of the lateral condyle of the femur
[Diagram: map of origin and insertions of leg muscles]
State the insertion of gastrocnemius.
The tendon of this muscle fuses with the tendon of the soleus to form the tendo calcaneus or tendo-Achilles, which is inserted into the middle third of the posterior aspect of the calcaneus.
Describe the origin of soleus.
1) back of the head and upper fourth of the posterior surface of the shaft of the fibula
2) soleal line and middle third of the medial border of the shaft of tibia
3) tendinous soleal arch between tibia and fibula
State the insertion of soleus.
Its tendon fuses with the tendon of gastrocnemius, which inserts on the posterior aspect of the calcaneus.
Name the sesamoid bone that may be found in the tendon of origin of the lateral head of gastrocnemius.
Fabella
State two actions of gastrocnemius.
- Plantar flexion of the ankle when the knee is extended
- Flexion of the leg at the knee joint
State the nerve that supplies gastrocnemius, soleus and plantaris and give its root values.
Tibial nerve (anterior rami of S1, S2)
State two actions of soleus.
- Plantar flexion of the ankle independent of the position of the knee
- Steadies the leg on the foot during standing
Describe the origin of plantaris (2).
- Lower part of the lateral supracondylar line of the femur
- Oblique popliteal ligament
- [Diagram: plantaris]
- [Diagram: osteology of the femur]
Describe the insertion of plantaris.
Its thin and long tendon inserts medial to the tendocalcaneus on the posterior aspect of the calcaneus. [Diagram]
Which muscle’s tendon is referred to as the Freshman’s nerve? Why is it reffered to in this way?
Plantaris muscle.
Reason: Its long, thin tendon is often mistaken for a nerve by first-year medical students during dissection. The plantaris muscle is a small muscle with a short belly and a long slender tendon.
[Cadaveric image]
Why is soleus called the peripheral heart?
There are large valveless venous sinuses within its mass. When it contracts, the blood in these sinuses is pumped upwards. When it relaxes, it sucks the blood from the superficial veins through the perforators.
What is the soleal arch, and what is its importance?
The soleal arch, also known as the tendinous arch of the soleus muscle, is a structure in the lower leg, formed by some fibers of the soleus muscle that arise from a tendinous arch placed between the tibial and fibular origins of the muscle.
IMPORTANCE: This arch spans over and protects the popliteal vessels and the tibial nerve as they run in front of it.
State one action of plantaris.
Very weak plantar flexion of the ankle
Describe the origin of popliteus.
- It has an intracapsular origin from the lateral aspect of the lateral condyle of the femur (popliteal groove of femur)
- Outer margin of the lateral meniscus of the knee joint
- [Cadaveric image 1] [Cadaveric image 2]
State the insertion of popliteus.
medial 2/3 of the posterior surface of the shaft of the tibia above the soleal line
