Location of the Cruropopliteal Canal
The canal is located in the deep posterior compartment (fascial space) of the leg. It runs inferiorly from the popliteal fossa toward the medial malleolus.
The canal is formed between two muscle layers:
- Superficial layer: Triceps surae muscle (m. triceps surae), specifically between the gastrocnemius (m. gastrocnemius) and soleus (m. soleus) muscles.
- Deep layer: Tibialis posterior (m. tibialis posterior), flexor digitorum longus (m. flexor digitorum longus), and flexor hallucis longus (m. flexor hallucis longus) muscles.
Proximally (superiorly), the canal is bounded by the popliteal fascia.
Openings and Borders
The canal has one inlet and two outlets that transmit blood vessels and nerves.
- Inlet: Structures enter the superior aspect of the canal.
- Anteriorly: Bounded by the popliteus muscle (m. popliteus).
- Posteriorly: Bounded by the tendinous arch of the soleus muscle (arcus tendineus m. solei).
- Upper outlet: Through this opening, the anterior tibial artery exits the canal by piercing the interosseous membrane to enter the anterior fascial compartment of the leg.
- Laterally: Neck of the fibula (collum fibulae).
- Superiorly: Popliteus muscle (m. popliteus).
- Medially and inferiorly: Origin of the tibialis posterior muscle (m. tibialis posterior).
- Lower outlet: Distally, the canal opens near the medial malleolus at the medial border of the soleus muscle (m. soleus), medial to the calcaneal (Achilles) tendon. In this region, the neurovascular bundle is covered only by the deep and superficial layers of the leg fascia.
Contents of the Cruropopliteal Canal
At the inlet (at the level of the tendinous arch of the soleus), the popliteal artery (a. poplitea) bifurcates into its terminal branches: the anterior and posterior tibial arteries. The anterior tibial artery leaves the canal through the upper outlet, while the posterior tibial artery, posterior tibial veins, and tibial nerve continue through the canal.
Contents of the canal:
- Tibial nerve (n. tibialis) — occupies the most superficial position relative to the artery within the bundle.
- Posterior tibial artery (a. tibialis posterior) — travels alongside the nerve.
- Posterior tibial veins (vv. tibiales posteriores) — venae comitantes accompanying the corresponding artery.
The neurovascular bundle travels inferiorly toward the medial malleolus (into the tarsal tunnel).
Clinical Significance
- Pseudo-claudication syndrome: Occurs due to compression of the neurovascular bundle within the cruropopliteal canal.
- Surgical approach: The canal serves as an important anatomical landmark for surgical exposure of the posterior tibial artery.
- Entrapment neuropathy / Tarsal tunnel syndrome: Can develop from compression of neurovascular structures posterior to the medial malleolus.