Upper motor neuron & Lower motor neuron lesions

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Definitions

Upper motor neuron

  • Corticospinal neuron
  • Corticonuclear neuron

Cerebral cortex (pyramidal tract) –> Precentral gyrus (motor strip) → internal capsule (posterior limb) → brainstem → spinal cord

  • 85% cross to opposite side

Upper motor neuron lesions

  • Interruption of the corticospinal and corticonuclear tract along its course

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Lower motor neuron

  • Neurons from the brain stem & spinal cord
    • efferent motor fibres
    • terminal axons & motor end plates
    • muscle fibres

Anterior horn cells in spinal cord→nerve roots→nerve plexus →peripheral nerves

Lower motor neuron lesions

  • Degeneration of the motor neuron & peripheral nerves

_____________________________________________________________________

Clinical features – Upper motor neuron lesion

  • Initial phase
    • limbs flaccid
    • loss of tendon reflexes
  • Several days to a week
    • return of motor function, but tone increases
  • Long term
    • Spasticity
    • Hyperreflexia
  • Ankle & patella clonus
  • Barbinski sign +ve
    • extensor plantar response
  • Absent abdominal reflexes

Examples of UMN lesion

  • Cerebrovascular accident
    • stroke! most common
  • Intracranial tumour
  • Cervical spine injury

Clinical features – Lower motor neuron lesion

  • Muscle wasting
  • Muscle weakness
    • reduced power
  • Hypotonia
  • Loss of reflexes
  • Fasciculations
  • Fibrillations
  • Associated changes in
    • skin, nail, hair

Examples of LMN lesion

  • Motor neuron disease
  • Peripheral nerve neuropathy
    • Diabetic neuropathy?
  • Poliomyelitis
    • anterior horn cell affected
  • Spinal cord injury
    • with nerve root compression

Examples of BOTH UMN & LMN lesion

  • Demyelinating disease
    • Multiple sclerosis

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image

Spinal cord injury

  • C1 – C5
    • Upper limbs: UMN
    • Lower limbs: UMN
  • C6 – T2
    • Upper limbs: LMN
    • Lower limbs: UMN
  • T3 – L3
    • Upper limbs: normal
    • Lower limbs: UMN
  • L4 – S2
    • Upper limbs: normal
    • Lower limbs: LMN

Facial nerve lesion

image

  • Upper motor neuron lesion
    • Contralateral lower quadrant weakness
      • Angle of the mouth
      • Opposite side
  • Lower motor neuron lesion
    • Ipsilateral orbicularis oculi muscle and facial muscles involved
      • Half of face
        • unable to close eyes
        • weakness of angle of the mouth
        • cannot elevate eyebrows
      • Same side

image

image

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EXTRA Reading:

http://en.wikiversity.org/wiki/Upper_vs_Lower_Motor_Neuron_Lesions

This entry was posted in Nervous System, Pathology, Uncategorized. Bookmark the permalink.

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58 Comments on "Upper motor neuron & Lower motor neuron lesions"

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ariff
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ariff

this is good overview of UMN n LMN… thank you for the info.. it saves me in the pbl session..

Arif
Guest
Arif

You must be in Mansoura University then right?

terrichan
Guest

Nop, I was from International Medical University (IMU) Kuala Lumpur

A Pakistani Boy
Guest

Thanks A Lot!

sumit garg
Guest
sumit garg

gud diff to remember

student
Guest
student

VERY GOOD REVIEW .. IT’S VERY ESY TO REMEMBER .. THANK YOU ALOT

dr nihaal shaikh
Guest
dr nihaal shaikh

thanks a lot .the best thing of it is its simplicity.

Safeeka Safreen
Guest
Safeeka Safreen

very simple

sabeen
Guest
sabeen

great. thanks alot

walter
Guest
walter

Good stuff

sam23
Guest
sam23

Great job; a nice piece with good illustrstions, even on phone.

nazish malik
Guest
nazish malik

i always found it difficult,upper lower,,,full half,,,but thnks now its refreshd again

tura
Guest
tura

good stuff to memorize.10q

Pippa
Guest
Pippa

Can someone please explain to me why the facial nerve features present the way they do with a UMN and a LMN lesion? Thank you.

Madhu Mathi. P
Guest
Madhu Mathi. P

very useful,thank u 🙂

trust
Guest
trust

This is good, too good

Upendra Nath Passi (State Ayurvedic Medical college Lucknow)
Guest
Upendra Nath Passi (State Ayurvedic Medical college Lucknow)

Thank’s

DR. IZHAR
Guest
DR. IZHAR

thakew 2 save me frm embarcment b4 my clss as tomorrow iz my presentation n i m preparing it wel frm here

abedi zakayo
Guest
abedi zakayo

thanks for the good explanation

david mbanye
Guest
david mbanye

thanks…for good preparation…! easy to undestand.

med
Guest

Admirable

bello Muhammd sokoto
Guest
bello Muhammd sokoto

Impressive performance keep up

bello Muhammd sokoto
Guest
bello Muhammd sokoto

Impressive performance keep it up thanks

yimer diress
Guest

IT IS NICE TO ME! THANKS…. FOR YOUR PREPARETION.

Love
Guest
Love

Very useful and helpful.thanks

ocholafelix
Guest

that was super.

Dr A Mannan
Guest
Dr A Mannan

Very infermativ

Thilagavathi
Guest
Thilagavathi

Nantri…

.Yasser
Guest
.Yasser

thanks ………. but
i need more details in order to be able to differentiate between UMNL and LMNL

Odongo Robert
Guest
Odongo Robert

This is really wonderful. its a great overview. thanks

omar7raul
Guest

Reblogged this on Omar7raul's Blog and commented:
nice work

Iddi Ibn SIna
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Iddi Ibn SIna

I am in Uganda, East Africa. This site is a must for all medics. It has helped me out in many topics

Yewloong
Guest
Yewloong

Greetings from Uni of Manchester, haha i am here for my quick scan through on UMN and LMN lesions for my 4th year OSCEs on Thursday. Fingers crossed.

narmeen kauser
Guest
narmeen kauser

that was really a great explaination

mchaki
Guest
mchaki

smple one and easy to remember,,

akoxix
Guest

wow.. you are from kuala lumpur?? same as me.. btw, nice article.. really easy to grasp for my presentation.. thanks.. XDXD

terrichan
Guest

Yeap 😉 Which med school are you from?

akoxix
Guest

USM Health Campus.. :):)

terrichan
Guest

I was from IMU 🙂

sonu
Guest
sonu

post polio syndrome is umn or lmn?

Kev
Guest

PPS is a LMN type pf lesion.

Kev
Guest

of*

Gunnashria
Guest
Gunnashria

Thanks a bunch. It was helpful.

judith
Guest
judith

Tnx alot

apeksha pawhse
Guest
apeksha pawhse

I want more eg.s of lmn and umn like stroke bells paslsy, preriferal neuropathy

Uche
Guest
Uche

Lovely overview, thanks

Medya Hashim
Guest

thank u very much :D: D

Viknesh Dev
Guest
Viknesh Dev

hey.. i have read most of your notes from MSK, CNS, and many other systems. they’re really good. i am from IMU as well and have shared it with most of my friends. most of whom really loved your site for the simplicity of the notes and the good diagrams.. really thanks!

terrichan
Guest

Thanks! Glad that my notes are helpful!

Dr. Hazrat Bilal Malakandi, PT
Guest
Dr. Hazrat Bilal Malakandi, PT

thank u so much …
especially the UMN and LMN in spinal cord injury …

Ufoaro Oliver Nwabueze
Guest
Ufoaro Oliver Nwabueze

Concise in content and presentation.

Dr Shrestha
Guest

Nice work, best notes as far as I saw online on this topic. Keep it up.

Harsha Kaluarachchi
Guest

thankz a lot.clear and nice work

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Bron
Guest
Bron

Please can someone explain the anatomical/physiological reasoning that spinal cord lesions above T6 are classified as UMN and below T6 are classified as LMN? Thanks!

Charles Nyaitara
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Charles Nyaitara

They are very helpful to me. How can I join with you?

Ashley
Guest

Hello! Great summary! Although I”m so confused why does Upper Motor Neuron lesion causes problesm for the lower quadrant of the face and Lower Motor Neuron lesion causes damage for half of the face? And I thought lower motor neuron is in the spinal cord?

jessica
Guest
jessica

you just completely saved my butt for my final tonight. thank you and happy holiday!

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