Motor Systems, Spinal Cord and Brainstem Flashcards
What are the three components of the brainstem?
Midbrain
Pons
Medulla Oblongata
Descending Motor Tracts have how many neurons?
2
The upper motor neuron of the Descending Motor Tract is located where?
Entirely in the Central Nervous System
What does Corticospinal and Corticobulbar tracts ennervate?
Corticospinal: Musculature of the body
Corticobulbar: Masculature of head and neck
What is the Corticospinal tract control?
Axial and limb motor control
Where does the Corticospinal tract begin?
Pre-central gyrus (Primary motor cortex)
Discuss in detail the Corticospinal Tract
- Two neurones begin at the pre-central gyrus and descend down into medulla
- At the medulla, 75-90% decussate (limb), and the rest don’t (axial)
- Fibres run down via the lateral (limb) and anterior corticospinal (axial) tract
- When they get to target level, fibres of anterior corticospinal tract decussate at the anterior white commisure and synapse to a neurone at anterior horn of grey matter
- Fibres of the lateral corticospinal tract have already decussated and synapse onto a neuron on anterior horn
- Anterior horn cells then project to the limb and axial muscles
What is the Corticospinal tract also known as?
Pyramidal tract
An upper motor neuron lesion can occur anywhere between?
From cortex to anterior horn
A lower motor neuron lesion can occur anywhere between?
Anterior horn to muscles
Paralysis would occur in which side, if there was transection above decussation in the Lateral Corticospinal tract?
Contralateral
Paralysis would occur in which side, if there was transection below decussation in the Lateral Corticospinal tract?
Ipsilateral
Horner’s Syndrome is due to a failure in which pathway?
Hypothalamospinal tract
Failure in the Hypothalamospinal Tract causes..?
Horner’s Syndrome
What are the symptoms of Horner’s Syndrome?
Ptosis (droopy eyelid)
Miosis (constricted pupil)
