Neuro Practical 2.1.3 Flashcards
what hemisphere is brocas area usually located in?
the dominant - usually left
Which region of the primary motor cortex gives rise to the upper motor neurons concerned with cortico-bulbar projections?
betz layer 5
Which region of the primary motor cortex gives rise to the upper motor neurons concerned with cortico-spinal projections?
betz layer 5
Where in the internal capsule are the corticospinal and corticobulbar fibres located?
posterior limb
The corticospinal fibres are nearer the retrolenticular region, corticobulbar fibres are nearer the genu.
what is the central sulcus?
divides the primary motor and primary sensory cortex
where is the premotor cortex?
anterior to the primary motor cortex
what is the cortico-spinal nerves function?
voluntary control of the limbs and trunk
what is the function of the cortico-bulbar nerves
voluntary movements of the head and neck, speech, swallowing, facial expresions
Where are the cell bodies of upper motor neurons in the corticospinal tract primarily located?
Principally in the primary motor cortex
Where are the cell bodies of lower motor neurons located?
In the ventral grey horn of the spinal cord. Their axons exit the spinal cord in the ventral root, and merge with the dorsal root to form a mixed spinal nerve.
What happens to the majority of descending corticospinal motor axons at the decussation of the pyramids?
they decussate to the contralateral side
Apart from their location, what is the main difference between the lateral and ventral corticospinal tracts?
Fibres in the lateral tract decussated in the medulla; fibres in the ventral tract are ipsilateral and will decussate in the spinal cord close to the vertebral level where their target lower motor neurons are located
describe the corticospinal tract
Primary motor cortex -> Corona radiata -> Internal capsule -> Crus cerebri -> Pyramid -> Decussation of the pyramid -> Lateral corticospinal tract -> Ventral horn
Do upper motor neurons in the lateral and ventral corticospinal tracts synapse on lower motor neurons in the ipsilateral or contralateral ventral grey horn of the spinal cord?
Nearly all synapse on to lower motor neurons on the contralateral side
what is another name for the corticospinal tract?
the pyramidal tract
what is the function of the corticospinal tract?
voluntary control of movement
what controls involuntary movement?
the extrapyramidal tracts
what are the extrapyramidal tracts?
- Rubrospinal – UMN cell bodies in the red nucleus
- Vestibulospinal – UMN cell bodies in the vestibular nuclei
- Tectospinal – UMN cell bodies in the superior colliculus
- Reticulospinal – UMN cell bodies in the reticular formation (hard to identify!)
where does the vestibulospinal nuceleus recieve information from and what does it activate?
receives from the labryinthine system and cerebellum
activates the extensor motor neurones concerned with maintenance of anti-gravity posture
where does the rubrospinal nucleus recieve information from and activate?
receives: cortex and cerebellum
activates: motor neurones and flexor muscles
where does the reticulospinal nucleus receive information from and what deos it activate?
receives: hypothalamus
actrivates : motor neurones concerned with reflex activity, muscle tone, breathing and circulatory system
where does the tectospinal nucleus recieve information from and activate
receives: visual system
activates: motor neurones reflex response to visual stimulo
what is the basal ganglia?
a group of subcortical nuclei with extensive connections to the cortex and thalamus (particlularly VA nucleus) they act as a checking system for motor activity - facilitate wanted movements and inhibit unwanted ones
what are the major componenets of the basal ganglia?
caudate nucleus, putamen, globus pallidus, substantia nigra
