NERVE INJURIES OF LOWER LIMBSHOMEOSTASIS TEST

TESTKhaleel Alyahya, PhD, MEdwww.khaleelalyahya.net

HOMEOSTASIS Khaleel Alyahya, PhD, MEdwww.khaleelalyahya.net

NERVE INJURIES OF LOWER LIMBSKhaleel Alyahya, PhD, MEdwww.khaleelalyahya.net

RESOURCES

Clinical Anatomy Gray’s Anatomy Clinical Neuroanatomy

Overview

▪ The lumbar plexus is a network of nerve fibres that supplies the skin

and musculature of the lower limb.

▪ It is located in the lumbar region, and it is formed by the anterior

rami (divisions) of the lumbar spinal nerves L1, L2, L3 and L4.

▪ The sacral plexus is a network of nerve fibres that supplies the skin and

muscles of the pelvis and lower limb.

▪ It is located on the surface of the posterior pelvic wall, anterior to the

piriformis muscle, and it is formed by the anterior rami (divisions) of the

sacral spinal nerves S1, S2, S3 and S4.

Khaleel Alyahya, PhD, MEd 3

Femoral Nerve

▪ The femoral nerve is one of the major peripheral nerves of the lower

limb.

▪ It originates from roots (L2-L4).

▪ Motor functions:

• Innervates the anterior thigh muscles that flex the hip joint and extend the

knee.

▪ Sensory functions:

• Supplies cutaneous branches to the anteromedial thigh (anterior cutaneous

branches of the femoral nerve) and the medial side of the leg and

foot (saphenous nerve).


Branches of Femoral Nerve

▪ Anterior division:

• Anterior cutaneous branches

• Branch to sartorius

• Branch to pectineus

▪ Posterior division:

• Saphenous nerve

• Branches to quadriceps femoris


Motor Functions

▪ Hip flexors:

• Pectineus adducts and flexes the thigh, assists with medial rotation of the

thigh.

• Iliacus acts with psoas major and psoas minor (forming iliopsoas) to flex the

thigh at the hip joint and stabilise the hip joint.

• Sartorius flexes, abducts and laterally rotates the thigh at the hip joint. Flexes

the leg at the knee joint.

▪ Knee extensors:

• Quadriceps femoris extends the leg at the knee joint.

• Rectus femoris also steadies the hip joint and assists iliopsoas in flexing the

thigh.


Sensory Functions

▪ Anterior cutaneous branches

• Derived from the anterior division of the femoral nerve.

• They supply the skin of the anteromedial thigh.

▪ Saphenous nerve

• Continuation of the posterior division of the femoral nerve.

• It supplies the skin of the medial leg and foot.


Femoral Nerve Block

▪ Femoral nerve block (in combination with a sciatic nerve block) may

be indicated in patients requiring lower limb surgery who cannot

tolerate a general anaesthetic.

▪ A femoral nerve block can also be used as perioperative and

postoperative analgesia for patients with a fractured neck of femur

who cannot tolerate particular analgesics.


Stripping of Saphenous Vein

▪ The saphenous vein is often stripped in individuals with problematic

varicose veins.

▪ The long saphenous vein is accompanied in its course by the

saphenous nerve.

▪ Damage to the saphenous nerve during this procedure can lead to

pain, paraesthesia or complete loss of sensation the medial side of the

lower leg.


Obturator Nerve

▪ The obturator nerve is also one of the major peripheral nerves of the

lower limb.

▪ It originates from roots (L2-L4).


• Innervates the muscles of the medial compartment of the thigh.


• Cutaneous branches of the obturator nerve innervate the skin of the medial

thigh.


Motor Functions

▪ The obturator nerve innervates all the muscles in the medial

compartment of the thigh (except the hamstring part of the adductor

magnus which is innervated by the tibial nerve).

▪ They are collectively known as the hip adductors:

• Adductor longus that adducts thigh

• Adductor brevis that adducts thigh

• Adductor magnus that adducts, flexes and extends thigh

• Gracilis that adducts thigh

• Obturator externus that laterally rotates thigh


Sensory Functions

▪ The cutaneous branch of the obturator nerve supplies the skin of the

middle part of the medial thigh.


Obturator Nerve Block

▪ Obturator nerve block is used in the management of pain after lower

limb surgery or for chronic hip pain.

▪ The anaesthetic is injected inferior to the pubic tubercle and lateral to

the tendon of the adductor longus muscle.

▪ This procedure can also be carried out under ultrasound guidance.


Obturator Nerve Damage

▪ The obturator nerve can be damaged during surgery involving the

pelvis or abdomen.

▪ Symptoms include numbness and paraesthesia on the medial aspect

of the thigh and weakness in adduction of the thigh.

▪ Alternatively, the patient could present with posture and gait problems

due to the loss of adduction.


Sciatic Nerve

▪ The sciatic nerve is also one of the major peripheral nerves of the

lower limb.

▪ It originates from roots (L4-S3).


• Innervates the muscles of the posterior thigh and the hamstring portion of the

adductor magnus (remaining portion of which is supplied by the obturator

nerve).

• Indirectly innervates all the muscles of the leg and foot.


• No direct sensory functions.

• Indirectly innervates the skin of the lateral leg, heel, and both the dorsal and

plantar surfaces of the foot.


Motor Functions

▪ The sciatic nerve indirectly innervates several other muscles, via its

two terminal branches:

• Tibial nerve: the muscles of the posterior leg (calf muscles), and some of the

intrinsic muscles of the foot.

• Common fibular nerve: the muscles of the anterior leg, lateral leg, and the

remaining intrinsic foot muscles.

▪ In total, the sciatic nerve innervates the muscles of the posterior thigh,

entire leg and entire foot.


Sensory Functions

▪ The sciatic nerve does not have any direct cutaneous functions.

▪ It provide indirect sensory innervation via its terminal branches:

• Tibial nerve: supplies the skin of the posterolateral leg, lateral foot and the

sole of the foot.

• Common fibular nerve: supplies the skin of the lateral leg and the dorsum

of the foot.


Piriformis Syndrome

▪ It refers to compression of the sciatic nerve by the piriformis muscle.

▪ It is also known as deep gluteal syndrome.

▪ Clinical features include radicular pain, numbness, muscle weakness

and buttock tenderness.

▪ The pain can occasionally be exacerbated by internal rotation of the

lower limb at the hip.

▪ X-ray and MRI imaging is usually unremarkable but can exclude other

pathology such as spinal compression of the sciatic nerve.

▪ The treatment of piriformis syndrome can be divided into non-

operative and operative:

• Non-operative – analgesia, physiotherapy and corticosteroid injections

• Operative – piriformis muscle release.


Intramuscular Injections

▪ The anatomical course of the sciatic nerve must be considered

when administering intramuscular injections into the gluteal

region.

▪ The sciatic nerve passes through the lower medial quadrant.

▪ To avoid damaging the sciatic nerve therefore, intramuscular

injections are given only in the upper lateral quadrant of the

gluteal region.


Tibial Nerve



• Innervates the posterior compartment of the leg and the majority of the

intrinsic foot muscles.


• Innervates the skin of the posterolateral leg, lateral foot and the sole of the

foot.


Motor Functions

• The tibial nerve innervates the muscles of the posterior leg and the

majority of the intrinsic foot muscles.

• The muscles of the posterior compartment of the leg are organised

into a superficial and deep compartment, and they are all innervated

by the tibial nerve.

• The medial and lateral plantar branches of the tibial nerve provide

innervation to all the intrinsic muscles of the foot (exept the extensor

digitorum brevis, which is innervated by the deep fibular nerve).


Sensory Functions

▪ In the popliteal fossa, the tibial nerve gives off cutaneous branches.

▪ These combine with branches from the common fibular nerve to form

the sural nerve.

▪ This sensory nerve innervates the skin of the posterolateral side of the

leg and the lateral side of the foot.

▪ The tibial nerve also supplies all the sole of the foot via three

branches:

• Medial calcaneal branches

• Medial plantar nerve

• Lateral plantar nerve:


Tibial Nerve Damage

▪ Damage to the tibial nerve is rare, and is often a result of direct

trauma, entrapment through narrow space or compression for long

period of time.

▪ Damage results in loss of plantar flexion, loss of flexion of toes and

weakened inversion (The tibialis anterior can still invert the foot).


Tarsal Tunnel Syndrome

▪ Tarsal tunnel syndrome refers to the compression of the tibial nerve as

it passes through the tarsal tunnel.

▪ Patients may experience altered sensation in the sensory distribution

of the tibial nerve – the sole of the foot.

▪ The motor function of the nerve can also be affected in severe

disease, causing weakness and wasting of the intrinsic foot muscles.


Common Fibular Nerve

▪ It also known as common peroneal nerve.



• Innervates the short head of the biceps femoris directly.

• Also supplies (via branches) the muscles in the lateral and anterior

compartments of the leg.


• Innervates the skin of the lateral leg and the dorsum of the foot.


Motor Functions

▪ The common fibular nerve innervates the short head of the biceps

femoris muscle (part of the hamstring muscles, which flex at the

knee)

▪ The terminal branches also provide innervation to muscles:

▪ Superficial fibular nerve:

• Innervates the muscles of the lateral compartment of the leg; fibularis

longus and brevis. These muscles act to evert the foot.

• Deep fibular nerve:

• Innervates the muscles of the anterior compartment of the leg.


Sensory Functions

▪ There are two cutaneous branches that arise directly from the common fibular

nerve as it moves over the lateral head of the gastrocnemius:

▪ Sural communicating nerve:

• Combines with a branch of the tibial nerve to form the sural nerve, which innervates the

skin over the lower posterolateral leg.

▪ Lateral sural cutaneous nerve:

• Innervates the skin over the upper lateral leg.

▪ The terminal branches of the common fibular nerve also have a cutaneous

function:

▪ Superficial fibular nerve:

• Innervates the skin of the anterolateral leg, and dorsum of the foot (except the skin

between the first and second toes).

▪ Deep fibular nerve:

• Innervates the skin between the first and second toes.


Common Fibular Nerve Damage

▪ The common fibular nerve is most commonly damaged by a fracture of

the fibula, or the use of a tight plaster cast.

▪ The anatomical course of the common fibular nerve causes it to wrap

round the neck of the fibular, and so any fractures of the fibular neck

can cause nerve palsy.

▪ Patients with common fibular nerve damage will lose the ability

to dorsiflex the foot at the ankle joint.

▪ Hence the foot will appear permanently plantarflexed (known

as footdrop).

▪ They may also present with a characteristic gait, as a result of the

footdrop.


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Tests & Procedures

Check page 158 from the book Mastering MedicalTerminology for the complete list of tests & procedures.

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NERVE INJURIES OF LOWER LIMBSHOMEOSTASIS TEST

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