blunt dissection of muscles to relax them and find the nerve easily. When the External Popliteal or Peroncal nerve is divided, foot drop occurs, necessitating a raised leg posture (steppage gait) to prevent stubbing the toe. This nerve bears an important relation to the knee-joint and tendon of the biceps. To expose the peroneal behind the head of the fibula, place the patient face down or on their sound side. The line of the nerve corresponds to the tendon of the biceps, which may be palpated along the external border of the popliteal space. In this line, beginning at the neck of the fibula, make an incision upward three inches long, dividing structures down to the deep fascia. Carefully divide the deep fascia over the tendon of the biceps and immediately there comes into view the external popliteal nerve lying to the inner side of the tendon resting upon the external condyle of the femur above, and lower down winding about the neck of the fibula and disappearing in the peroncus longus. To expose the musculo-cutaneous nerve, place the patient on their back with the knee flexed and rotated inward, exposing the external aspect of the leg. The line of the nerve is drawn from the anterior border of the popneal head to the anterior border of the external malleolus. Along this line, in the middle of the leg, make an incision three or four inches long dividing structures to the deep fascia. Incise the aponeurosis of the peronei muscles and isolate the anterior border of the peroncus longus and draw it backward. The nerve will be seen resting upon the peroneus brevis (Fig. 239). To expose the anterior tibial nerve, put the patient in the same position as for the musculo-cutaneous. The line of the nerve is drawn from the front of the popneal head to the middle of the ankle-joint (Fig. 240). In the upper third, make an incision beginning three fingers’ breadth below the articular line of the knee, divide to the deep fascia; next divide that and then patiently search for the intermuscular septum separating the wide tibialis anticus from the narrow common extensor. Retracting the muscles, the nerve will appear as a small rounded white cord lying in front of the vessels. To expose the posterior tibial nerve in the region of the calf is difficult (Fig. 241). Place the patient on their back with the thigh abducted and externally rotated, knee flexed, foot lying upon its external border held by an assistant. Standing to the outside of the limb, locate first the sharp internal border of the tibia, make an incision four inches long beginning at the level of the tuberosity. Divide tissues down to deep fascia avoiding the internal saphenous vein close to the tibial border. Retract posterior lip including gastrocemius exposing soleus; divide it longitudinally but further away from the tibia than original incision (Fig. 242). Cutting through fibers of the soleus exposes yellow aponeurosis covering nerve and vessels, make an opening in it one inch and a half from internal border of tibia beneath is the nerve lying to outer side of artery. <Callout type="important" title="Critical Step">When exposing nerves, always ensure you are not damaging blood vessels or other critical structures.</Callout>
The posterior tibial nerve supplies movements of extension of foot and flexion of toes. It may be wounded in any part of its course, although difficult to expose in the region of calf.
Key Takeaways
- Identify and locate nerves accurately using anatomical landmarks.
- Use blunt dissection to relax muscles for easier access to nerves.
- Understand the consequences of nerve damage, such as foot drop.
Practical Tips
- Practice identifying major nerves on a cadaver or model before an emergency situation arises.
- Always have sterilized instruments and materials ready when performing surgery.
Warnings & Risks
- Avoid damaging blood vessels while exposing nerves to prevent excessive bleeding.
- Ensure proper patient positioning to facilitate nerve exposure without causing additional injury.
Modern Application
While modern medical practices offer advanced imaging techniques and surgical tools, the anatomical knowledge and basic principles of nerve repair described in this chapter remain crucial. Understanding these historical methods can be invaluable for remote or resource-limited settings where sophisticated equipment is unavailable.
Frequently Asked Questions
Q: What are the consequences if the external popliteal nerve is damaged?
If the external popliteal nerve is divided, foot drop occurs, meaning the patient cannot walk without stubbing their toe and must raise their leg to prevent this.
Q: How do you expose the peroneal nerve behind the head of the fibula?
To expose the peroneal nerve behind the head of the fibula, place the patient face down or on their sound side. Make an incision upward from the neck of the fibula for three inches, dividing structures to the deep fascia.
Q: What is the significance of the anterior tibial nerve?
The anterior tibial nerve continues from the external popliteal nerve and controls movements such as flexion of the foot and extension of the toes. It can be exposed by making an incision three fingers’ breadth below the articular line of the knee.