POSTERIOR Fascial Compartment of the Lower Limb

Question 1

Gastrocnemius

Intrinsic or Extrinsic?
Origin
Insertion
Nerve supply
Action

Answer 1

Extrinsic

Origin: Lateral head from lateral condyle of femur and medial head from above medial condyle

Insertion: Via tendo calcaneus into posterior surface of calcaneum

Nerve supply: Tibial nerve

Action: Plantar flexes foot at ankle joint; flexes knee joint

Question 2

Plantaris

Intrinsic or Extrinsic?
Origin
Insertion
Nerve supply
Action

Answer 2

Extrinsic

Origin: Lateral supracondylar ridge of femur

Insertion: Posterior surface of calcaneum

Nerve supply: Tibial nerve

Action: Plantar flexes foot at ankle joint; flexes knee joint

Question 3

Soleus

Intrinsic or Extrinsic?
Origin
Insertion
Nerve supply
Action

Answer 3

Extrinsic

Origin: Shafts of tibia and fibula

Insertion: Via tendo calcaneus into posterior surface of calcaneum

Nerve supply: Tibial nerve

Action: Together with gastrocnemius and plantaris is powerful plantar flexor of ankle joints; provides main propulsion force in walking or running

Question 4

Tibialis Posterior

Intrinsic or Extrinsic?
Origin
Insertion
Nerve supply
Action

Answer 4

Extrinsic

Origin: Posterior surface of shafts of tibia and fibula and interosseous membrane

Insertion: Tuberosity of navicular bone and other neighboring bones

Nerve supply: Tibial nerve

Action: Plantar flexes foot at ankle joint; inverts foot at subtalar and transverse tarsal joints; supports medial longitudinal arch of foot