Anatomy of Nerve Injuries Anatomy of Nerve Injuries Lower LimbLower Limb

By- Dr. Armaan SinghBy- Dr. Armaan Singh

» Dermatomes» Entrapment of Nerves» Pierce Muscle» Pierce Fascia» Repetitive Movements

» Must know the course of nerve» Dermatomes» Entrapment of nerves» Pierce muscle» Pierce fascia» Repetitive movements

Nerves supply

» Skin

» Muscles (group)

» Tendons

» Bones

» Joints

» Blood vessels

» External forces » Fibro-osseous tunnels, tether

the nerve» Oedema» Callus formation as a result of a

fracture » External compression due to

specific movements» Mechanical compression » Compartment syndromes» The nerve is tender at the site

of compression

» Fibrous bands» Accessory muscles» Spurs» Narrow notches» Anatomical variations of the nerve

itself

» Affects branches of lumbar or sacral plexuses

» Pierces muscle» Pierces fascia» Increase in

compartment pressure» Compressed by external

pressure

» Lower five intercostal nerves» Subcostal nerve T12» 10th intercostal nerves at the

level of the umbilicus» Iliohypogastric nerve L1» Ilioinguinal nerve L1

» Subcostal nerve T12» Iliohypogastric nerve L1» Ilioinguinal nerve L1» Femoral branch of the

genitofemoral nerve L1,2» Lateral cutaneous nerve of

the thigh L2,3» Femoral nerve L2,3,4» Obturator nerve L2,3,4

Cutaneous Nerves

» Branch of lumbar plexus» Lateral border of psoas» Anterior to quadratus

lumborum» Neurovascular plane

between internal oblique and transversus

» Lateral cutaneous supplies upper part of buttock

» Pierces internal oblique above anterior superior iliac spine

» Pierces aponeurosis of external oblique an inch

above superficial ring » Supplies skin over

lower part of rectus sheath

» Can be trapped piercing aponeurosis

Iliohypogastric Nerve

» Ilioinguinal nerve» L1 branch of lumber plexus» Lateral border of psoas» Anterior to quadratus

lumborum» Neurovascular plane between

internal oblique and transversus

Ilioinguinal Nerve

» Pierces internal oblique 4 cm medial to

» Anterior superior iliac spine

» Enters inguinal canal» Leaves through

superficial ring» Supplies the skin of the

medial part of the thigh» Adjoining portion of the

scrotum and labia

Ilioinguinal Nerve

» May be trapped post surgery, due to adhesions

» Poor tone in abdominal muscles

» Pain increased by increased tension in the anterior abdominal wall

» Hyperextension of hip» Tenderness 4 cm from

anterior superior iliac spine

Ilioinguinal Nerve

» Pain increased» Increased tension in the

anterior abdominal wall» Hyperextension of hip» Tenderness 4 cm medial to

anterior superior iliac spine

Ilioinguinal Nerve Entrapment

» Iliohypogastric in 5.6%» Ilioinguinal 90.7%» Union of branches of

ilioinguinal and genital branch of the genitofemoral nerve 13%

» Genitofemoral passing through superficial inguinal ring 35.2%

» Piercing inguinal ligament 5.6%

» Femoral branch 13% Akita et al., 1999

» Lumbar plexus L1,2» Anterior aspect of the

psoas» Genital branch enters the

deep inguinal ring» Femoral branch lies on the

lateral side of femoral artery in the femoral sheath

» Enters thigh on lateral aspect of femoral artery in femoral sheath

» Pierces anterior wall of the sheath

» Supplies skin a hands breath below the inguinal ligament

» Union with ilioinguinal nerve on anterior aspect of spermatic cord

» Supplies ventral aspect of scrotum and adductor region

» Cutaneous branch on the dorsal-caudal aspect

» May also supply dorsal scrotum

Akita et al., 1999

Genitofemoral Nerve

Genitofemoral Nerve

» Lumbar plexus in psoas» Lateral aspect of psoas» Pierces inguinal ligament» Lies in fibrous tunnel» Divides into two» Pierces deep fascia

» A centimeter medial to anterior superior iliac spine

» Crosses the lateral angle of femoral triangle

» Divides into two» Pierces deep fascia» Anterolateral aspect of

the thigh» Anterior portion of

gluteal region

LCN

Lateral Cutaneous Nerve of Thigh

» Entrapment in the fascial tunnel

» Injured in the thigh by asymmetric bars in gymnastics

» Causes meralgia paraesthetica

» Post laparoscopic surgery

Lateral Cutaneous Nerve of Thigh

» Largest branch of the lumbar plexus» Lateral aspect of psoas» Passes under the inguinal ligament» Outside femoral sheath» 2 cm below» Divides into terminal branches» Muscular » Articular» Cutaneous

Muscular branches»Rectus femoris»Vastus medialis,»Vastus lateralis»Vastus intermedius»Sartorius, pectineusCutaneous »Medial cutaneous nerves of thigh»Intermediate cutaneous nerves of thigh»Saphenous Articular branches to hip and knee joints

Femoral Nerve

» Dancers may stretch the nerve by prolonged hyperextension of the hip

» Compress the nerve under the inguinal ligament

» Nerve may also be compressed due to a haematoma following a partial tear of the iliacus

O’Brien, 1997

Femoral Nerve

Femoral nerve

Saphenous

Femoral Nerve

» Lumbar plexus in psoas» Medial aspect of psoas» Side wall of pelvis under

peritoneum» Leaves through obturator

foramen» Divides into anterior and

posterior divisions

Obturator Nerve L2,3,4

» Supplies the parietal peritoneum on side wall of the pelvis

» Is related to the ovary» Pathology in the ovary or

endometriosis may result in referred pain to the hip, knee or medial side of the high

Obturator Nerve

» Anterior division of the obturator leaves pelvis

» Anterior to obturator externus

» Descends in front of adductor brevis

» Behind pectineus and adductor longus

Obturator nerve

» Adductor longus » Adductor brevis» Gracilis» It gives an articular twig

to the hip joint» Skin on the medial side

of the thigh

Anterior Division Obturator

Obturator Nerve

» It may be entrapped as it leaves the pelvis

» Pierces and supplies the obturator externus

» Causing spasm of the adductor muscles

Posterior Division Obturator

» Supplies adductor portion of adductor magnus, above hiatus

» Articular twig to knee joint and cruciate ligaments

» Causing spasm of the adductor muscles

» It may be entrapped as it leaves the pelvis or between fascial planes

Posterior Division Obturator

Obturator nerve

Obturator Nerve

Fascial planes

» Pressure on obturator nerve

» Pain on inner aspect of thigh relieved by flexion of hip

» Increased by extension, adduction and medial rotation

Obturator Nerve

» Compression of pudendal nerve in cyclists due to saddle

» History of change of saddle» Compressing dorsal nerve of

penis

Pudendal Nerve

» Is the largest nerve in diameter in the body

» It passes out of the pelvis below piriformis and descends between the greater trochanter of the femur and the ischial tuberosity

» Passes deep to gluteus maximus

» More distally it lies on adductor magnus

» Is crossed by the long head of biceps femoris

» Divides in middle of thigh» Tibial and common

peroneal nerves» Common peroneal may

pierce piriformis if divides in pelvis

» Supplies hamstrings » Adductor magnus below

hiatus

Sciatic Nerve

» Occasionally it divides in the pelvis

» Then the common peroneal portion may pierce the piriformis muscle to enter the thigh

» Recurrent injury to the hamstring muscles produces inflammation and possible scarring which could interfere with the normal mobility of the sciatic nerve and produce clinical signs of adverse neural tension

Sciatic Nerve

» The larger terminal branch of the sciatic nerve

» Crosses popliteal fossa» Passes deep to soleus» In posterior compartment between

flexor digitorum longus flexor hallucis longus

» Passes deep to flexor retinaculum » Gives off medial calcaneal nerve

which pierces retinaculum» Divides into medial and lateral

plantar nerves

Tibial Nerve

» The tibial nerve supplies all the muscles of the posterior compartment of calf

» In popliteal fossa gives off » Superomedial, middle and inferomedial

genicular branches» Nerve to medial and lateral heads of

gastronemii» Plantaris» Popliteus » Soleus» Sural nerve

Tibial Nerve

» Medial side of psoas» Side wall of pelvis» Obturator canal» Divides anterior posterior

division

» Sural nerve is joined by sural communicating from commom peroneal

» Pierces deep fascia » Supplies posterior and

lateral portion of calf» Lateral border of foot» Entrapment occurs most

frequently in runners with a history of ankle sprain

Sural Nerve

Sural Nerve

» Deep fascia from medial malleolus to medial margin of calcaneus

Anterior to posterior» Tibialis posterior» Flexor digitorum longus» Posterior tibial artery » Tibial nerve» Both give off medial calcaneal artery and nerve» Then both divide into medial and lateral plantar

branches» Flexor hallucis longus

» Gives off the medial calcaneal nerve under cover of the retinaculum

» It then pierces the flexor retinaculum to supply the posterior and medial aspect of the heel

Tibial Nerve

» Tibial divides into the medial and lateral plantar nerves

» They enter two tunnels separated by a fascial septum

» Stretching from the calcaneus to the deep fascia of the abductor hallucis

» Passes under the abductor hallucis

» Then runs on the plantar surface of the flexor digitorum longus

» Dividing into its digital branches

» Sensory to the plantar aspect of the medial three and a half toes

Medial Plantar Nerve

» Motor to the abductor hallucis» Flexor hallucis brevis» Flexor digitorum brevis » First or unipennate lumbrical

Medial Plantar Nerve

» Crosses the sole of the foot deep to the abductor hallucis, flexor digitorum brevis and the abductor digiti minimi

» To the base of 5th metatarsal

» Superficial to flexor hallucis longus, flexor digitorum longus and flexor accessorius

» Lateral plantar nerve supplies the lateral one-and-a-half toes

» Supplies all the other intrinsic muscles of the foot

Medial Plantar Nerve

» The tibial nerve may be compressed in the proximal portion of the tunnel before it divides

» More distally, either the medial or lateral plantar nerves may be involved

» Hyper dorsiflexion, external rotation and eversion can produce symptoms of tarsal tunnel syndrome

» Pain worse if foot is pronated

» Tender over flexor retinaculum

» Pain in heel, if medial calcaneal is involved

» Pain in sole of foot if plantar nerves involved

» Orthotics may help if marked pronated foot

» Anti-inflammatories» Splint at night

» Depressed transverse arch in runners and ballet dancers with mobile first ray

» Neuroma on digital nerve to the second cleft or third cleft

morton neuroma.jpg

Morton’s Foot

» Pronated foot» Depressed transverse

arch at heads of metatarsals

» Pain worse with tight shoes on

» Relieved by removing shoes

Medial Plantar

» If sciatic nerve divides inside the pelvis

» Common peroneal nerve pierces the piriformis

» May be entrapped» In popliteal fossa» The common peroneal

nerve lies between the tendon of biceps femoris and the lateral head of gastrocnemius

» In popliteal fossa gives off» Lateral cutaneous of calf» Sural communicating» Superior lateral, inferior lateral

genicular nerves» Leaves fossa at lateral angle» Crosses neck of fibula deep to

peroneus longus » Gives off recurrent genicular, deep

and superficial peroneal» Vulnerable to injury as it winds around neck of

fibula» Foot drop, plantar flexed, inverted

Common Peroneal

» Nerves can be compressed in compartments

» Anterior compartment deep peroneal nerve

» Lateral compartment superficial peroneal

» Posterior compartment tibial nerve

» Branch of the common peroneal at the neck of the fibula

» Pierces the lateral inter-muscular septum to enter the anterior compartment

» Supplies all muscles in anterior compartment tibialis anterior, extensor hallucis longus, extensor digitorum longus, peroneus tertius and extensor digitorum brevis

» Skin of cleft between first and second toes» The nerve may be compressed due to

anterior compartment syndrome» Muscle most at risk is tibialis anterior» Entrapment occurs most frequently in

runners. It also occurs in soccer players, dancers and skiers

» It occurs most often under the inferior extensor retinaculum. Repetitive ankle sprains, tight fitting shoes or trauma may also cause entrapment

Deep Peroneal Nerve

» Runs in the lateral compartment of the calf

» Between the peroneus longus and brevis supplying both these muscles

» Pierces the deep fascia 10–12 cm above the lateral malleolus supplies most of the dorsum

Superficial Peroneal Nerve

» Divides 6 cm above the lateral malleolus into branches, which supply the dorsum of the foot

» The first cleft is supplied by the deep peroneal

» The lateral border is supplied by the sural nerve

» Medial border to ball of big toe saphenous

» Rest superficial peroneal

» Entrapment occurs where the superficial peroneal pierces the deep fascia

» Particularly if there is herniation of the muscle due to fascial defects

» Chronic ankle strains also stretch the nerve

» Grade III ankle injuries have a high incidence of traction injuries to both the peroneal and posterior tibial nerves

Taunton & Fricker, 1996