Upper And Lower Motor Neuron Lesions

Front 1

Skeletal muscle influenced by CNC

Back 1

through two sets of neuron :
i. Upper motor neuron
ii. Lower motor neuron
- Upper motor neuron control lower motor neuron
through two different pathways :
a) Pyramidal tract
b) Extra pyramidal tract

Front 2

motor neuron pathways

Back 2

 Pyramidal Tracts

 Corticospinal tract
 Extrapyramidal Tracts-
 Reticulospinal
 Olivospinal
 Vestibulospinal
 Tectospinal
 Rubrospinal tract
 Corticobulbar tract
 Corticorubral tract

Front 3

Descending corticospinal (pyramidal) motor tracts

Back 3

Front 4

Upper Motor Neuron Lesions

Back 4

- Interruption of the corticospinal and corticonuclear tract along itscourse.

- also known as pyramidal insufficiency.
- It is a lesion of the neural pathway above the anterior horn cell of the spinal cord or motor nuclei of the cranial nerves.
- This is in contrast to a lower motor neuron lesion, which affects nerve fiber (anterior horn of the spinal cord to the relevant muscle).
- Affecting motor neurons in the brain or spinal cord such as stroke, multiple sclerosis, traumatic brain injury and cerebral palsy

Front 5

Symptoms of UMN Lesions

Back 5

- Changes in muscle performance.

- These changes vary depending on the site and the extent of the lesion, and may include:
- Muscle weakness
- Decreased control of active movement, particularly slowness
- Spasticity
- Clasp-knife response
- Babinnski sign

- increase deep tendon reflex (DTR)
- Pronator drift

Front 6

Examples of UMN Lesion

Back 6

 Cerebrovascular accident
- Stroke (most common)
 Intracranial tumour
 Cervical spine injury

Front 7

lower motor neurons

Back 7

- All voluntary movement depend upon excitation of lower motor neuron by upper motor neuron

- These are the only neurons that innervate the skeletal muscle fibers, they function as the final common pathway, the final link between the CNS and skeletal muscle

Front 8

Lower Motor Neuron Lesion

Back 8

 It is a lesion which affects nerve fibers traveling from the anterior horn of the spinal cord to the relevant muscle of the lower motor neuron.

 One major characteristic used to identify a lower motor neuron lesion is flaccid paralysis(reduced/loss muscle tone).
 This is in contrast to an upper motor neuron lesion, which often presents with spastic paralysis (paralysis
accompanied by severe hypertonia).

Front 9

Sign of LMN Lesion

Back 9

 Flaccid paralysis of muscles supplied.

 Atrophy of muscles supplied.
 Loss of reflexes of muscles supplied.
 Muscles fasciculation (contraction of a group of fibers)
 Musclefibrillation (contraction of individual fibers)
 Muscle contracture (shortening of paralyzed muscles)
 Presence of muscle wasting

Front 10

Example of LMN Lesion

Back 10

 Motor neuron disease

 Peripheral nerve neuropathy
- Diabeticneuropathy
 Poliomyelitis
- anterior horn cell affected
 Spinal cord injury
- with nerve root compression

Front 11

UMN and LMN Lesions

Back 11

* 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