- Sciatic Nerve
- Largest branch of Sacral Plexus
- Formed at lower margin of Piriformis by union of its Tibial and Common Peroneal parts
- Passes into buttock lying on posterior surface of Ischium
- Superficial to nerve to Quadratus Femoris and deep to Posterior Femoral Cutaneous Nerve
- Passes vertically downwards into the hamstring compartment midway between the Greater Trochanter and the Ischial Tuberosity
- Lies on Obturator Internus and Gemelli, Quadratus Femoris and then on Adductor Magnus
- Overlaid by the Long Head of Biceps
- Main trunk supplies all Hamstrings and Ischial fibres of Adductor Magnus
- Then divides (at the upper angle of the Popliteal Fossa) into the Tibial and Common Peroneal Nerves
- Branches to the Long Head of Biceps, the two Semi- muscles and Adductor Magnus are from the Tibial part and the branch to the Short Head of Biceps comes from the Common Peroneal Part
- Common peroneal nerve (L4, L5, S1, S2)
- Supplies extensor and peroneal compartments of the leg and dorsum of foot
- Enters apex of Popliteal Fossa
- Runs medial to the Biceps tendon
- Crosses Plantaris, Lateral Head of Gastrocnemius and curves around neck of the Fibula through Peroneus Longus
- Divides into two terminal branches – Deep and Superficial Peroneal (Fibular) Nerves
- Most commonly injured nerve of the lower limb
- Common Peroneal Nerve itself supplies no muscles
- Three articular branches (Upper and Lower Lateral and Recurrent Genicular Nerves) supply knee joint
- Two cutaneous Nerves – Sural Communicating Nerve and the Lateral Cutaneous Nerve of the Calf
- Deep Peroneal nerve
- Formed in the substance of Peroneus Longus
- Spirals down over the Fibula deep to Extensor Digitorum Longus
- Reaches the Interosseous membrane
- Runs down lateral to the vessels
- Crosses the lower end of the Tibia and Dorsum of Foot
- Ends by supplying skin of the First Interdigital Cleft
- Supplies: Extensor Digitorum Longus, Tibialis Anterior, Extensor Hallucis Longus, and Peroneus Tertius and Extensor Digitorum Brevis
- Superficial Peroneal nerve
- Formed in the substance of Peroneus Longus
- Emerges from the anterior border 1/3 of the way down the leg
- Supplies Peroneus Longus and Brevis
- Perforates the fascia to supply the skin over the Peronei and Extensor muscles in lower 1/3 of the leg
- Above the ankle, it divides into a medial and lateral branch which supply the skin and deep fascia on the Dorsum of the foot
- Medial branch supplies the medial side of the big toe and the 2nd interdigital cleft
- Lateral branch supplies the 3rd and 4th clefts
- Tibial nerve (L4, L5, S1, S2, and S3)
- Supplies the calf and sole of foot around to the toenails
- Enters Apex of Popliteal Fossa
- Passes vertically down deep to the Heads of Gastrocnemius behind the knee joint
- Across the Popliteus muscle
- Runs beneath the Fibrous Arch in Soleus
- Branches in Popliteal Fossa:
- 3 x Genicular Nerves
- Branches to muscles: Plantaris, both heads of Gastrocnemius, Soleus and Popliteus
- Sural Nerve
- Lies in groove between the two heads of Gastrocnemius and pierces deep fascia halfway down the legs
- Runs alongside the Small Saphenous Vein behind the Lateral Malleolus
- Ends on the lateral side of the little toe
- Runs down with the Posterior Tibial Vessels deep to Soleus
- Neurovascular bundle lie in the groove between Flexor Hallucis Longus and Flexor Digitorum Longus
- Divides into its terminal Medial and Lateral Plantar branches behind the Medial Malleolus, beneath the Flexor Retinaculum
- Branches in the Calf:
- 4 x muscular branches – Soleus, Tibialis Posterior, Flexor Hallucis Longus, Flexor Digitorum Longus
- Medial Calcanean branches pierce the Flexor Retinaculum and supply the weight-bearing skin of the heel
- Medial and Lateral Plantar Nerves
- Medial Plantar: Medial part of sole, plantar surface of medial 3 ½ digits, Flexor Digitorum Brevis, Abductor Hallucis, Flexor Hallucis Brevis, and 1st lumbrical
- Lateral Plantar: Supplies the rest of the sole and other small foot muscles
