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
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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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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
- Upper motor neuron lesion
- Contralateral lower quadrant weakness
- Angle of the mouth
- Opposite side
- Contralateral lower quadrant weakness
- 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
- Half of face
- Ipsilateral orbicularis oculi muscle and facial muscles involved
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EXTRA Reading:
http://en.wikiversity.org/wiki/Upper_vs_Lower_Motor_Neuron_Lesions
this is good overview of UMN n LMN… thank you for the info.. it saves me in the pbl session..
You must be in Mansoura University then right?
Nop, I was from International Medical University (IMU) Kuala Lumpur
Thanks A Lot!
gud diff to remember
VERY GOOD REVIEW .. IT’S VERY ESY TO REMEMBER .. THANK YOU ALOT
thanks a lot .the best thing of it is its simplicity.
very simple
great. thanks alot
Good stuff
Great job; a nice piece with good illustrstions, even on phone.
i always found it difficult,upper lower,,,full half,,,but thnks now its refreshd again
good stuff to memorize.10q
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.
very useful,thank u 🙂
This is good, too good
Thank’s
thakew 2 save me frm embarcment b4 my clss as tomorrow iz my presentation n i m preparing it wel frm here
thanks for the good explanation
thanks…for good preparation…! easy to undestand.
Admirable
Impressive performance keep up
Impressive performance keep it up thanks
IT IS NICE TO ME! THANKS…. FOR YOUR PREPARETION.
Very useful and helpful.thanks
that was super.
Very infermativ
Nantri…
thanks ………. but
i need more details in order to be able to differentiate between UMNL and LMNL
This is really wonderful. its a great overview. thanks
Reblogged this on Omar7raul's Blog and commented:
nice work
I am in Uganda, East Africa. This site is a must for all medics. It has helped me out in many topics
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.
that was really a great explaination
smple one and easy to remember,,
wow.. you are from kuala lumpur?? same as me.. btw, nice article.. really easy to grasp for my presentation.. thanks.. XDXD
Yeap 😉 Which med school are you from?
USM Health Campus.. :):)
I was from IMU 🙂
post polio syndrome is umn or lmn?
PPS is a LMN type pf lesion.
of*
Thanks a bunch. It was helpful.
Tnx alot
I want more eg.s of lmn and umn like stroke bells paslsy, preriferal neuropathy
Lovely overview, thanks
thank u very much :D: D
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!
Thanks! Glad that my notes are helpful!
thank u so much …
especially the UMN and LMN in spinal cord injury …
Concise in content and presentation.
Nice work, best notes as far as I saw online on this topic. Keep it up.
thankz a lot.clear and nice work
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!
They are very helpful to me. How can I join with you?
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?
you just completely saved my butt for my final tonight. thank you and happy holiday!