Lecture 2: Nervous System 2 Flashcards
What is the CNS comprised of?
the brain and spinal cord
What is the PNS defined as?
the nerves connecting the CNS to the body, and includes a number of ganglia at specific locations along these peripheral nerves
What are Brodmann areas of the brain?
result of microscopic analysis of the whole brain, looking for differences in organisation -> based on cellular differences
Where is the brainstem located?
between the diencephalon (inter-brain) and the spinal cord
What is the brainstem composed of?
the midbrain, pons and medulla oblongata
What is the central sulcus surrounded by?
the primary somatosensory cortex and the primary somatomotor cortex
What is the lateral fissure surrounded by?
primary auditory and gustatory cortices
What is the calcerine sulcus surrounded by?
primary visual cortex
Where are the upper motor neurons located?
in the primary motor cortex
Where are the lower motor neurons located?
in the spinal cord
What is the motor homunculus?
the size of cortical surface responsible for a part of the body is proportional to the degree of motor control needed for that part
What are primary cortices surrounded by?
secondary cortices and secondary cortices are surrounded by tertiary (highest order) cortices
What is each lobe of the brain composed of?
functional cortical areas called the primary, secondary and tertiary cortex
In which direction does a motor signal travel through the brain to initiate movement?
from the prefrontal cortex (highest order) to the supplementary motor cortex and the premotor cortex (secondary motor cortices) to the primary motor cortex to the spinal cord -> somatomotor output
What does the SMC and PMC contribute to?
learning sequence of movements and stores skilled (know-how), sensory integration and bilateral coordination (especially upper limbs)
What does lesion/damage to the primary motor cortex or upper motor neuron result in?
paresis or paralysis (spastic) - i.e. hypertonia
What does lesion/damage to the lower motor neuron either in the spinal cord, ventral root or nerve result in?
paresis or paralysis (flaccid) i.e. hypotonia/atonia
What does lesion/damage to the premotor cortex / supplementary motor area / other movement planning areas result in?
apraxia
What is apraxia?
inability to execute a voluntary motor movement despite being able to demonstrate normal muscle function; it also includes ability to initiate a movement
What are the two cortico-spinal tracts which travel from the motor cortex to the ventral horn of the spinal cord?
the lateral and anterior cortico-spinal tracts / motor systems
How many upper motor neuron axons cross to the other side of the body?
most (80%) cross at the level of the brainstem in the lateral cortico-spinal tract and a few (20%) cross at the level of the spinal cord in the anterior cortico-spinal tract
What is the internal capsule?
a collection of myelinated axons situated close to the basal ganglia and is the location of the major cortico-spinal tract
What does the internal capsule contain?
contains all of the upper motor neuron axons
What are the terms lateral and anterior derived from?
from where in the spinal cord the descending tracts are found
Where do upper motor neuron axons cross?
at the level of the medulla in the brainstem within the medullary pyramids
Where are axons found in the pyramidal pathways for motor control?
in the pyramids of the medulla -> involved in controlling voluntary movements
Where are cell bodies of the lower motor neurons found?
in the ventral horn of the spinal cord
What are the types of motor and descending pathways in the body?
pyramidal tracts and extrapyramidal tracts
What are the types of sensory and ascending pathways in the body?
dorsal column medial lemniscus system, spinocerebellar tracts and the anterolateral system
What is the pyramidal system?
pathway for voluntary movement
most fibres originate in motor cortex and cross to contralateral side at the medulla
What is the extrapyramidal system?
pathways for coordination of movement and control posture / muscle tone
cortex can influence this system via inputs to brain stem
