TeachMe Physiology

Question 1

Where does the cell body of an upper motor neuron originate and terminate?

Answer 1

Origin: Cerebral cortex
Termination: Ventral horn of the spinal cord

Question 2

Where in the brain does the upper motor neuron (UMN) of the corticobulbar tract originate?

Answer 2

Pre-central gyrus of the cortex

Question 3

Where in the brain does the upper motor neuron (UMN) of the corticospinal tract originate?

Answer 3

Pre-central gyrus of the cortex

Question 4

What is the main neurotransmitter involved in the transmission from upper to lower motor neurons?

Answer 4

Glutamate

Question 5

Passive flexion and extension of elbow joint. More resistance the faster the extension.

What is this called?

Answer 5

Spasticity

Question 6

What is Babinski’s sign?

Answer 6

Large toe extends/dorsiflexes and the other toes abduct on stroking a blunt object along the lateral border of the plantar surface of the foot

Question 7

What is the primary function of α-motor neurons within the spinal cord?

Answer 7

Muscle contraction

Question 8

Which type of motor neurons plays a key role in maintaining muscle tone and nonconscious proprioception?

Answer 8

Gamma-motor neurons

Question 9

Lower motor neurons (LMNs) release which neurotransmitter at the neuromuscular junction (NMJ) ?

Answer 9

Acetylcholine

causes muscle fibres to contract

Question 10

What are the components of a “motor unit” ?

Answer 10

Lower motor neuron + muscle fibres

Question 11

Fasciculations (small involuntary muscle twitches) are a sign of damage to which motor neuron ?

Answer 11

Lower motor neuron

Question 12

Which type of lower motor neuron (LMN) is responsible for the symptoms and signs seen in LMN lesions?

Answer 12

Alpha-motor neurons

Question 13

Spinal muscular atrophy (autosomal recessive disorder) - where is the pathology ?

Answer 13

Loss of:

• motor neurons in the ventral horn of the spinal cord
• motor nuclei of the cranial nerves