Nerves of the Leg

Question 1

Saphenous nerve

Answer 1

Longest branch of the femoral nerve

Question 2

Course of saphenous nerve

Answer 2

o Enters adductor canal with femoral artery
o Crosses over the artery from lateral to medial in the canal
o Leaves the canal by passing to the surface on the medial side of the knee
o NOTE: nerve does NOT pass through adductor canal
o As saphenous nerve becomes superficial, it passes between the tendons of the sartorius and gracilis muscles
o Then runs with the great saphenous vein along the medial side of the leg

Question 3

Branching of the saphenous nerve

Answer 3

In the proximal 2/3 of the leg, it divides into two branches

• Contributing branch to subsartorial nerve plexus
• Infrapatellar branch (which provides cutaneous innervation to skin over patella)

In the distal 1/3 of the leg, it divides into its two terminal branches

• Branches to skin of the anterior and medial side of the leg (and one that continues distally to end at the ankle
• A branch that continues to the medial side of the foot as far down as the ball

Question 4

Tibial nerve

Answer 4

The larger component of the sciatic nerve

Question 5

Course of tibial nerve

Answer 5

o Originates from the anterior division of the sciatic nerve (L4-S3)
o Passes distally through the middle of the popliteal fossa
o Crosses the popliteus muscle and disappears between the heads of the gastrocnemius and deep to the soleus muscle
o Proximally, the tibial nerve lies lateral to the popliteal artery and vein
o In the popliteal fossa, it crosses superficial to these vessels and leaves the popliteal fossa medial to them
o Contributes deep to soleus muscle, eventually lying medial to tendo calcaneus

Question 6

Terminal branches of tibial nerve

Answer 6

The tibial nerve divides into its two terminal branches at the flexor retinaculum:

• Medial plantar nerve
• Lateral plantar nerve

Question 7

Position of tibial nerve

Answer 7

o In the proximal leg, the tibial nerve is medial to the posterior tibial artery
o Just distal to the inferior border of the popliteus muscle, it courses to the lateral side of the popliteal artery

Question 8

Articular branches of the tibial nerve

Answer 8

• 3 branches to knee joint which correspond to superior, inferior medial and middle genicular arteries
• 1 branch to the ankle joint

Question 9

Muscular branches of the tibial nerve

Answer 9

Proximal muscular branches supply the following muscles:
- Gastrocnemius
- Plantaris
- Soleus
- Popliteus
NOTE: these muscular branches arise as the tibial nerve passes between the heads of the gastrocnemius muscle

Distal muscular branches supply the following muscles:

• Soleus
• Tibialis posterior
• Flexor digitorum longus
• Flexor hallucis longus (branch to the flexor hallucis longus accompanies the peroneal artery)

Question 10

Medial sural cutaneous nerve

Answer 10

o Lies superficial in the groove between the heads of the gastrocnemius with the small saphenous vein
o Pierces the fascia at the middle of the leg and merges with the communicating ramus of the lateral sural cutaneous branch of the common peroneal nerve
o Together, these form the sural nerve
o Sural nerve continues distally, supplying cutaneous branches to the skin of the posterior surface of the leg
o It also communicates with the posterior femoral cutaneous nerve
o It enters the foot by passing under the lateral malleolus and continues as the lateral dorsal cutaneous nerve

Question 11

Medial calcaneal nerves

Answer 11

• Distributed to the skin of the heel and medial sole

Question 12

Medial and lateral plantar nerves

Answer 12

• Two terminal branches of the tibial nerve

Question 13

Common peroneal (fibular) nerve

Answer 13

• Smaller terminal branch of the sciatic nerve

- Originates from the posterior division of the sciatic nerve (L4-S2)

Question 14

Course of common peroneal nerve

Answer 14

o After it separates from the tibial nerve, it passes diagonally across the lateral portion of the popliteal fossa parallel to the medial border of the long head of the biceps femoris
o As it approaches the head of the fibula, it passes between the long head of the biceps femoris and the lateral head of the gastrocnemius
o After circling around the neck of the fibula, it passes deep to the peroneus (fibularis) longus and divides into superficial and deep fibular branches

Question 15

Articular branches of common peroneal nerve

Answer 15

Before dividing into its terminal branches, the common peroneal nerve gives rise to three articular branches to the knee:

• 1 accompanies superior lateral genicular artery
• 1 accompanies the inferior lateral genicular artery
• 1 accompanies the anterior tibial recurrent artery through the tibialis anterior muscle

Question 16

Lateral sural cutaneous branch

Answer 16

o Distributed to the posterior and lateral surface of the knee
o Has a communicating ramus, which joins medial sural cutaneous nerve to form sural n.

Question 17

Terminal branches of common peroneal nerve

Answer 17

• Superficial peroneal nerve

- Deep peroneal nerve

Question 18

Superficial peroneal nerve

Answer 18

o One of the terminal branches of the common peroneal nerve
o Arises deep to the peroneus longus
o Passes inferiorly between the peroneus longus and extensor digitorum longus
o Gives rise to two dorsal cutaneous branches supplying the foot
o Muscular branch: Superficial peroneal has muscular branches to the peroneus longus and brevis

Question 19

Deep peroneal nerve

Answer 19

o Passes from its origin deep to the peroneus longus muscle to the anterior surface of the interosseous membrane
o It accompanies the anterior tibial artery from the proximal 1/3 of the leg and passes with it deep to the extensor retinaculum
o Immediately distal to the extensor retinaculum, it divides into medial and lateral terminal branches

Question 20

Muscular branches of deep peroneal nerve

Answer 20

The deep peroneal nerve gives muscular branches to the following muscles
• Tibialis anterior
• Extensor digitorum longus
• Peroneus tertius and extensor hallucis longus

Question 21

Articular branch of deep peroneal nerve

Answer 21

The deep peroneal nerve gives an articular branch to the ankle joint

Question 22

Variation in the sural nerves and their branches

Answer 22

• Sural branches may be lacking or may extend to the ankle
• Sural nerve is formed by a union of the medial sural cutaneous and peroneal communicating branch in 80% of persons. In the remaining 20%, the sural nerve originates from the medial sural cutaneous nerve only