Central nervous system (7) Flashcards
How can we divide the brain?
>forebrain: -cerebral hemispheres - diencephalon-- thalamus and hypothalamus >midbrain >hindbrain: -pons -medulla -cerebellum
What is the basic function of the frontal lobe?
regulating and initiating motor function, language, cognitive functions (executive function/planning, attention, memory)
What is the basic function of the parietal lobe?
sensation (touch, pain), sensory aspects of language, spatial orientation and self-perception
What is the basic function of the temporal lobe?
processing auditory information
What is the basic function of the occipital lobe?
processing visual information
What divides the frontal and parietal lobes?
central sulcus
What is the limbic lobe?
- includes amygdala, hippocampus, mammillary body and cingulate gyrus
- concerned w/ learning, memory, emotion, motivation and reward
What is the insular cortex/lobe?
- lies deep to lateral fissure
- concerned w/ visceral sensations, autonomic control, interoception, auditory processing and visual-vestibular integration
What are the 3 layers of the meninges?
- dura mater
- arachnoid mater
- pia mater
What forms sinuses in the meninges?
the 2 layers of the dura
Where is cerebrospinal fluid produced?
in modified epithelial cells (choroid plexus) in lateral, 3rd and 4th ventricles–> goes to sub-arachnoid space
Where is CSF reabsorbed into the bloodstream?
via arachnoid villi (granulations) into superior sagittal sinus
What are the differences between CSF and plasm?
- lower pH
- less glucose
- much less protein
- less K+
Where do the efferent/afferent signals travel to/from in the spinal cord (N.B. roots)?
afferent signals coming into spinal cord at dorsal root, into dorsal horn–> efferent signals come out of ventral horn
What does the dorsal root ganglion contain?
cell bodies of sensory neurons
Where are the cell bodies of motor neurons?
ventral horn of spinal cord
What is the posterior ramus?
small branch of mixed spinal nerves–> supplies back
What are the regions of the spinal cord and how many segments are there in each?
- cervical (8)
- thoracic (12)
- lumbar (5)
- sacral (5)
- coccygeal (1)
Where do pairs of nerves emerge from the vertebrae?
intervertebral foramina–> space between 2 vertebrae
How does the relationship between nerves and intervertebral foramina change between cervical and thoracic regions?
- nerves C1-C7 emerge above vertebrae
e.g. C3 comes out between C2 and C3 bones - whereas nerves C8-Co1 emerge below vertebrae e.g. T11 comes out between T11 and T12 bones
(bc vertebral column more spread out)
What are the spinal cord enlargements?
- cervical enlargement at C5–> innervation of upper limbs
- lumbar enlargement at L2–> innervation of lower limbs
- bc lots of innervation
What is the major pathway for voluntary movement (descending)?
corticospinal tract: consists of upper motor neuron (in brain/primary motor cortex) and lower motor neuron (in brainstem and spinal cord)
–> upper motor neuron synapses w/ lower motor neuron
What are the major ascending pathways (sensation)?
- dorsal column pathway: for fine touch, vibration and proprioception
- spinothalamic pathway: for pain, crude touch and temperature from skin
Where is the primary motor cortex located?
pre-central gyrus (strip in front of central sulcus)
What is somatotopy?
where a region of body is represented in the brain e.g. if we stimulate a certain point on brain, a specific part of body moves
Where does the corticospinal tract decussate?
in medulla- 85% of fibres cross over to other side (supplying limbs, not trunk)
but synapses in spinal cord
What is the corticobulbar tract?
motor from 1y motor cortex to brainstem then to facial muscles
Where is the primary somatosensory cortex located?
post-central gyrus
What are the 2 parts of the spinothalamic pathway?
anterior spinothalamic tract (pain and temperature) and lateral spinothalamic tract (crude touch)
Where are the 3 neurons in the sensory pathways?
- 1y sensory neuron: receptor in skin, cell body in dorsal root
- 2y sensory neuron: cell body in spinal cord for spinothalamic OR medulla for dorsal column–> travels to thalamus
- 3y sensory neuron: cell body in thalamus–> travels to somatosensory cortex
At what neuron do the sensory pathways decussate?
at synapse between 1y and 2y sensory neuron
i.e. in medulla or spinal cord
What determines the size of somatotopic areas in the post-central gyrus?
the density of sensory receptors in that body region
Where does the dorsal column pathway decussate?
medulla
also synapses here
Where does the spinothalamic pathway decussate?
spinal cord
also synapses here
What are the 2 parts of the corticospinal tract?
lateral (limbs) and anterior (axial muscles)
