PERIPHERAL NERVES OF THE FOOT
Nerves in the Foot ,
Presentation,
Viktoras Kubaitis 23/04/2013
Five nerves are responsible for the foot innervation. They are Superficial and Deep Peroneal nerves, Sural, Tibial and Saphenous nerves. Peroneal Deep and Superficial nerves start from Posterior Tibial nerve in popliteal fossa and makes sensation for anterior and lateral aspect of the foot. Sural nerve starts in the same site and finishes over the lateral aspect of the foot behind the lateral malleolus. Tibial nerve stats as part of Ischial nerve, spreads in to medial and lateral plantar nerves in hind foot and is responsible for sole and heal sensation. Saphenous nerve comes from Femoral nerve origin from Hunter’s canal anteromedial aspect of the thigh and it is responsible for innervations of skin over the medial malleolus.
Foot’s anatomy closely related with lower leg anatomy. Injury or tightness in lower leg compartments can disturb function of foot distally. Each tibial compartment has his own nerve. Anterior compartment has Deep Peroneal nerve, Lateral – Superficial Peroneal nerve, Deep Posterior – tibial nerve and Superficial Posterior – Sural nerve. A design of these compartments is easier to remember when we would imagine a Tractor on a hill with his main 4 parts. Posterior tibial compartmens become Tarsal tunnel with 6 important structures and a tibial nerve and artery inside. Finally it Tibial nerve divides to medial and lateral plantar nerves. It is easier to remember when we imagine picture of Vikings and mnemonic: Tom Dick and Very Nervous and Angry Harry. Foot architecture with its 9 compartments can be compared with Castle.
Bony geometry and position of nerves changes in different levels. All these nerves are sensory –motor –vegetative. One peripheral nerve consist of at least couple roots nerves and for that reason neighbouring roots overlapping each other in one dermatome. For that reason it is prissier to test Autonomous Zones, which are inervated only by single nerve root. But it is still quite time consuming and physically demanding job. The quickest way is to test just ASIA points in particular sites: L4 – medial malleolus, L5 – lateral posterior side of the heel, S1 – dorsal point between 1st and 2nd metatarsals.
Anamnesis is important especially in diagnosis of The Secretary’s syndrome – compression of common peroneal nerve. The inspection of disturbance of innervation some times is related with loss of hears on the skin but sometimes when nerve damage is due to hypoxia it can be different. Pressure sores usually is related with diabetic neuropathy it can as well due to posttraumatic nerve lesion. Motoric function can be assessed by Mnemonic Buda hand: L1-sensoric, L2-hip flexion, L3-knee extension, L4-ankle extension, L5-Hallux IP extension. There are two tests related with nerve injury: Mulder’s Sign for Morton’s Neuroma and Extension – Eversion Sign for Tarsal tunnel. Posterior Tarsal tunnel syndrome is related with Flexor retinaculum. Anterior tarsal tunnel syndrome which is quite rear is related with Superior extensor retinaculum.
Iatrogenic injury is related with surgen’s blade, assistant Homman’s retractors and selfretainers. We are founding sensation loss and delayed healing of the wounds. Lateral malleolus C type fracture is related with superficial peroneal nerve lesion because in a distal third of lower leg its position usually is not ‘2’ but ‘3’. Delayed surgery and comminuted B type fractures related with Sural nerve lesion because from position ‘5’ it comes to position ‘3’ in distal tip of malleolus. Saphenous nerve position is something between ‘9 – 10’. For that reason if we doing incision over medial malleolus to anteriorlly, we always getting bleeding, stitching big vein and getting 5 cm numbness patch anteriorlly. Deep peroneal nerve can be cut in McBride soft tissue procedure or even in simple Hallux valgus Shevron osteotomy if there is big deformity of foot. Posterolateral approach to ankle is rear but comfortable for tibial posterior margin ORIF. Sural nerve can be damaged. We cannot achieve long incision in intermetatarsal surgery. Total ankle replacement incision internervous plane is between deep and superficial nerves. Calcaneus lateral approach can damage sural nerve in two places. External fixation of the ankle can be dangerous to saphenous, plantar and deep peroneal nerve. Some time it can come together with arterial damage as well.
Five nerves are responsible for the foot innervation. They are Superficial and Deep Peroneal nerves, Sural, Tibial and Saphenous nerves. Peroneal Deep and Superficial nerves start from Posterior Tibial nerve in popliteal fossa and makes sensation for anterior and lateral aspect of the foot. Sural nerve starts in the same site and finishes over the lateral aspect of the foot behind the lateral malleolus. Tibial nerve stats as part of Ischial nerve, spreads in to medial and lateral plantar nerves in hind foot and is responsible for sole and heal sensation. Saphenous nerve comes from Femoral nerve origin from Hunter’s canal anteromedial aspect of the thigh and it is responsible for innervations of skin over the medial malleolus.
Foot’s anatomy closely related with lower leg anatomy. Injury or tightness in lower leg compartments can disturb function of foot distally. Each tibial compartment has his own nerve. Anterior compartment has Deep Peroneal nerve, Lateral – Superficial Peroneal nerve, Deep Posterior – tibial nerve and Superficial Posterior – Sural nerve. A design of these compartments is easier to remember when we would imagine a Tractor on a hill with his main 4 parts. Posterior tibial compartmens become Tarsal tunnel with 6 important structures and a tibial nerve and artery inside. Finally it Tibial nerve divides to medial and lateral plantar nerves. It is easier to remember when we imagine picture of Vikings and mnemonic: Tom Dick and Very Nervous and Angry Harry. Foot architecture with its 9 compartments can be compared with Castle.
Bony geometry and position of nerves changes in different levels. All these nerves are sensory –motor –vegetative. One peripheral nerve consist of at least couple roots nerves and for that reason neighbouring roots overlapping each other in one dermatome. For that reason it is prissier to test Autonomous Zones, which are inervated only by single nerve root. But it is still quite time consuming and physically demanding job. The quickest way is to test just ASIA points in particular sites: L4 – medial malleolus, L5 – lateral posterior side of the heel, S1 – dorsal point between 1st and 2nd metatarsals.
Anamnesis is important especially in diagnosis of The Secretary’s syndrome – compression of common peroneal nerve. The inspection of disturbance of innervation some times is related with loss of hears on the skin but sometimes when nerve damage is due to hypoxia it can be different. Pressure sores usually is related with diabetic neuropathy it can as well due to posttraumatic nerve lesion. Motoric function can be assessed by Mnemonic Buda hand: L1-sensoric, L2-hip flexion, L3-knee extension, L4-ankle extension, L5-Hallux IP extension. There are two tests related with nerve injury: Mulder’s Sign for Morton’s Neuroma and Extension – Eversion Sign for Tarsal tunnel. Posterior Tarsal tunnel syndrome is related with Flexor retinaculum. Anterior tarsal tunnel syndrome which is quite rear is related with Superior extensor retinaculum.
Iatrogenic injury is related with surgen’s blade, assistant Homman’s retractors and selfretainers. We are founding sensation loss and delayed healing of the wounds. Lateral malleolus C type fracture is related with superficial peroneal nerve lesion because in a distal third of lower leg its position usually is not ‘2’ but ‘3’. Delayed surgery and comminuted B type fractures related with Sural nerve lesion because from position ‘5’ it comes to position ‘3’ in distal tip of malleolus. Saphenous nerve position is something between ‘9 – 10’. For that reason if we doing incision over medial malleolus to anteriorlly, we always getting bleeding, stitching big vein and getting 5 cm numbness patch anteriorlly. Deep peroneal nerve can be cut in McBride soft tissue procedure or even in simple Hallux valgus Shevron osteotomy if there is big deformity of foot. Posterolateral approach to ankle is rear but comfortable for tibial posterior margin ORIF. Sural nerve can be damaged. We cannot achieve long incision in intermetatarsal surgery. Total ankle replacement incision internervous plane is between deep and superficial nerves. Calcaneus lateral approach can damage sural nerve in two places. External fixation of the ankle can be dangerous to saphenous, plantar and deep peroneal nerve. Some time it can come together with arterial damage as well.
