Anatomy of Nerve Injuries Lower Limb BMJ

7/28/2019 Anatomy of Nerve Injuries Lower Limb BMJ

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MOB TCD

Anatomy of Nerve InjuriesLower Limb

Professor Emeritus Moira OBrien

FRCPI, FFSEM, FFSEM (UK), FTCD

Trinity College

Dublin


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Anatomy of Nerve Injuries

Dermatomes Entrapment of Nerves

Pierce Muscle

Pierce Fascia

Repetitive Movements

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Must know the course of nerve Dermatomes

Entrapment of nerves

Pierce muscle

Pierce fascia

Repetitive movements

Anatomy of Nerve InjuriesMOB TCD


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Dermatomes and Myotomes

Nerves supply Skin

Muscles (group)

Tendons

Bones

Joints

Blood vessels

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Extrinsic Factors

External forces Fibro-osseous tunnels, tether

the nerve

Oedema

Callus formation as a result of afracture

External compression due tospecific movements

Mechanical compression Compartment syndromes

The nerve is tender at the siteof compression

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Fibrous bands

Accessory muscles

Spurs

Narrow notches

Anatomical variations of the nerve itself

Extrinsic FactorsMOB TCD


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Lumbosacral PlexusMOB TCD


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Entrapment Syndromes

in Lower Limb

Affects branches of lumbaror sacral plexuses

Pierces muscle

Pierces fascia

Increase in compartmentpressure

Compressed by external

pressure

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Skin of Anterior Abdominal Wall

Lower five intercostal nerves Subcostal nerve T12

10th intercostal nerves at the

level of the umbilicus

Iliohypogastric nerve L1 Ilioinguinal nerve L1

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Cutaneous Nerves of Thigh

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

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Cutaneous NervesMOB TCD


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Iliohypogastric Nerve L1

Branch of lumbar plexus Lateral border of psoas

Anterior to quadratus

lumborum

Neurovascular plane betweeninternal oblique and

transversus

Lateral cutaneous supplies

upper part of buttock

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Pierces internal obliqueabove anterior superior

iliac spine

Pierces aponeurosis of

external oblique an inchabove superficial ring

Supplies skin over lower

part of rectus sheath

Can be trapped piercingaponeurosis

Iliohypogastric NerveMOB TCD


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Pierces internal oblique4 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 NerveMOB TCD


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May be trapped postsurgery, due to adhesions

Poor tone in abdominal

muscles

Pain increased byincreased tension in the

anterior abdominal wall

Hyperextension of hip

Tenderness 4 cm fromanterior superior iliac spine

Ilioinguinal NerveMOB TCD


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Pain increased Increased tension in the anterior

abdominal wall

Hyperextension of hip

Tenderness 4 cm medial to anteriorsuperior iliac spine

Ilioinguinal Nerve EntrapmentMOB TCD


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Cutaneous Nerves

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

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Genitofemoral Nerve

Lumbar plexus L1,2

Anterior aspect of the psoas

Genital branch enters the deep

inguinal ring

Femoral branch lies on thelateral side of femoral artery in

the femoral sheath

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Femoral Branch Genitofemoral

Enters thigh on lateral aspectof femoral artery in femoral

sheath

Pierces anterior wall of the

sheath

Supplies skin a hands breath

below the inguinal ligament

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Union with ilioinguinal nerveon anterior aspect of

spermatic cord

Supplies ventral aspect of

scrotum and adductor region

Cutaneous branch on the

dorsal-caudal aspect

May also supply dorsal

scrotumAkita et al., 1999

Genitofemoral NerveMOB TCD


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Genitofemoral NerveMOB TCD

C


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Lateral Cutaneous Nerve

of Thigh L2,3

Lumbar plexus in psoas Lateral aspect of psoas

Pierces inguinal ligament

Lies in fibrous tunnel

Divides into two

Pierces deep fascia

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A centimeter medial toanterior 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 ThighMOB TCD

MOB TCD


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Entrapment in the fascial tunnel Injured in the thigh by

asymmetric bars in gymnastics

Causes meralgia paraesthetica

Post laparoscopic surgery

Lateral Cutaneous Nerve of ThighMOB TCD

MOB TCD


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Femoral Nerve L2,3,4

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

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Muscular branches Rectus femoris

Vastus medialis,

Vastus lateralis

Vastus intermedius Sartorius, pectineus

Cutaneous

Medial cutaneous nerves of thigh

Intermediate cutaneous nerves of thigh Saphenous

Articularbranches to hip and knee joints

Femoral NerveMOB TCD

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Dancers may stretch thenerve 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 iliacusOBrien, 1997


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Femoral nerve

Saphenous


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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 L2,3,4MOB TCD

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Supplies the parietalperitoneum on side wall of the

pelvis

Is related to the ovary

Pathology in the ovary orendometriosis may result in

referred pain to the hip, knee or

medial side of the high

Obturator NerveMOB TCD

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Anterior Division Obturator

Anterior division ofthe obturator

leaves pelvis

Anterior to

obturator externus

Descends in front

of adductor brevis

Behind pectineus

and adductor

longus

Obturator nerve

O C

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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

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Obturator Nerve

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It may be entrapped as it leaves the pelvis

Pierces and supplies the obturator externus

Causing spasm of the adductor muscles

Posterior Division Obturator

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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

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Obturator nerve

Obturator Nerve

Fascial planes

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Howship Rhomberg Sign

Pressure on obturator

nerve

Pain on inner aspect of

thigh relieved by flexion of

hip

Increased by extension,

adduction and medial

rotation

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Obturator Nerve

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Psoas Muscle

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Sacral Plexus

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Pudendal Nerve

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Compression of pudendal nerve in

cyclists due to saddle

History of change of saddle

Compressing dorsal nerve of penis

Pudendal Nerve

Sciatic NerveMOB TCD


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Sciatic Nerve

Posterior Cutaneous Nerve Thigh

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Sciatic Nerve L4,5, S1,2,3

Is the largest nerve indiameter 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

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Is crossed by the long headof 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

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Occasionally it divides in thepelvis

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 thesciatic nerve and produce

clinical signs of adverse neural

tension

Sciatic Nerve

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The larger terminal branch of thesciatic nerve

Crosses popliteal fossa

Passes deep to soleus

In posterior compartment betweenflexor digitorum longus flexor

hallucis longus

Passes deep to flexor retinaculum

Gives off medial calcaneal nervewhich pierces retinaculum

Divides into medial and lateral

plantar nerves

Tibial Nerve

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The tibial nerve supplies all the muscles of theposterior 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

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Obturator Nerve L2,3,4

Medial side of psoas Side wall of pelvis

Obturator canal

Divides anterior posterior

division

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Sural nerve is joined by suralcommunicating from

commom peroneal

Pierces deep fascia

Supplies posterior and lateralportion of calf

Lateral border of foot

Entrapment occurs most

frequently in runners with ahistory of ankle sprain

Sural Nerve

S l NMOB TCD


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Sural Nerve

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Flexor Retinaculum

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 plantarbranches

Flexor hallucis longus

Tibi l NMOB TCD


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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

M di l d L l Pl NMOB TCD


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Medial and Lateral Plantar Nerves

Tibial divides into the medial and lateralplantar nerves

They enter two tunnels separated by a

fascial septum

Stretching from the calcaneus to the deepfascia of the abductor hallucis

M di l Pl t NMOB TCD


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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 themedial three and a half toes

Medial Plantar Nerve



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Motor to the abductor hallucis

Flexor hallucis brevis

Flexor digitorum brevis

First or unipennate lumbrical




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Crosses the sole of the foot deep to theabductor hallucis, flexor digitorum brevis

and the abductor digiti minimi

To the base of 5th metatarsal

Superficial to flexor hallucis longus, flexordigitorum longus and flexor accessorius

Lateral plantar nerve supplies the lateralone-and-a-half toes

Supplies all the other intrinsic muscles ofthe foot


T l T l S dMOB TCD


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Tarsal Tunnel Syndrome

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 beinvolved

Hyper dorsiflexion, external

rotation and eversion can

produce symptoms of tarsaltunnel syndrome

T l T l S dMOB TCD


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Pain worse if foot ispronated

Tender over flexor

retinaculum

Pain in heel, if medialcalcaneal is involved

Pain in sole of foot if

plantar nerves involved


T l T l S dMOB TCD


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Orthotics may help if markedpronated foot

Anti-inflammatories

Splint at night


T l T l S dMOB TCD


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M t M t t l i

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Mortons Metatarsalgia

Depressedtransverse arch in

runners and ballet

dancers with mobile

first ray

Neuroma on digital

nerve to the second

cleft or third cleft

morton neuroma.jpg

Mortons Foot

M di l Pl tMOB TCD


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Pronated foot

Depressed transversearch at heads ofmetatarsals

Pain worse with tight

shoes on Relieved by removing

shoes

Medial Plantar

Common Peroneal NerveMOB TCD


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L4,5, S1,2,3

If sciatic nerve divides insidethe 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 lateralhead of gastrocnemius

Common PeronealMOB TCD


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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, deepand superficial peroneal

Vulnerable to injury as it winds around neck of fibula

Foot drop, plantar flexed, inverted

Common Peroneal

Compartments in CalfMOB TCD


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Compartments in Calf

Nerves can becompressed in

compartments

Anterior compartment

deep peroneal nerve

Lateral compartment

superficial peroneal

Posterior compartment

tibial nerve

Deep Peroneal NerveMOB TCD


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Deep Peroneal 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 inanterior compartment tibialis

anterior, extensor hallucis

longus, extensor digitorum

longus, peroneus tertius andextensor digitorum brevis

Deep Peroneal NerveMOB TCD


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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 causeentrapment

Deep Peroneal Nerve

Superficial Peroneal NerveMOB TCD


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Runs in the lateralcompartment of the calf

Between the peroneus longus

and brevis supplying both

these muscles Pierces the deep fascia

1012 cm above the lateral

malleolus supplies most of

the dorsum

Superficial Peroneal Nerve

Nerve Supply of DorsumMOB TCD


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Nerve Supply of Dorsum

Divides 6 cm above the lateralmalleolus 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

Superficial Peroneal NerveMOB TCD


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Superficial Peroneal Nerve

Entrapment occurs where the

superficial peroneal piercesthe deep fascia

Particularly if there is

herniation of the muscle due

to fascial defects Chronic ankle strains also

stretch the nerve

Ankle InjuriesMOB TCD


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Ankle Injuries

Grade III ankle injuries have a high

incidence of traction injuries to both theperoneal and posterior tibial nerves

Taunton & Fricker, 1996

Documents

Anatomy of Nerve Injuries Lower Limb BMJ