Session 5 - Lecture 1: Upper and Lower Motor Neurones Flashcards
What is the location of a upper motor neurone cell body within the CNS?
Primary motor cortex.
What is the location of a lower motor neurone cell body within the CNS?
Brainstem and ventral horn of the spinal cord.
What is the effect of UMNs on LMNs?
Net inhibition of LMNs by UMNs via inhibitory interneurones.
What are the signs of a LMN lesion?
Weakness, wasting, hypotonia, areflexia and fibrillations.
What are the signs of an UMN lesion?
Weakness, hypertonia (spasticity and clasp knife reflex), hyperreflexia and extensor plantar reflexes.
What is spinal shock?
Immediately after an UMN lesion, LMNs decrease in their level of activity even though they are usually inhibited by UMNs. After a few days, UMN lesion signs will begin to present. You can think of it as LMNs getting ‘depressed’ after it has been deprived of its inputs.
What are the signs of a LMN lesion of the facial nerve?
Hemiparalysis on the ipsilateral side of the face.
What are the signs of an UMN lesion of the facial nerve?
Paralysis on lower quadrant of the face on the contralateral side.
What is the name of the tract that the UMNs/LMNs pass through?
Lateral corticospinal tract.
Describe the route of UMNs/LMNs through its tract.
UMN cell bodies being in the primary motor cortex (head and neck is more lateral, limbs are more medial). UMNs pass through the corona radiata within the white matter and through the internal capsule (located in between the thalamus and lentiform nucleus). UMNs decussate at the level of the caudal medulla and synapses close to the level of the structure it innervates. LMNs cell bodies reside in the brainstem and ventral horn of spinal cord.
Where in the LCS tract do neurones supplying the arm, trunk and neck descend?
Arm –> Leg
Medial –> Lateral
