Structure and layout of major brain areas; Sensory and motor pathways Flashcards
What are sulcus/sulci?
Furrows/valleys
What are gyrus/gyri?
Hills
What are the sections of the brain?
Frontal, parietal, occipital, temporal lobes
What are the major gyri, sulci and fissures of the brain?
- Central sulcus: separates frontal and parietal lobes
- Parito-occipital sulcus: separates parietal and occipital lobes
- Lateral sucus: separates temporal lobe rom frontal and parietal lobes
- Transverse fissure: separates cerebellum from cerebrum
What are the functions associated with lobes of the cerebellum (cerebral cortex)?
Parietal lobe:
- Somatosensory
Occipital lobe:
- Vision
Temporal lobe:
- Memory
- Hearing
Frontal:
- Motor control (upper)
- Language (lower)
- Personality (lower)
What are the major divisions of the brain: medial view?
- cerebral cortex (cerebrum)
- corpus callosum (white matter)
- diencephalon
- thalamus
- hypothalamus - cerebellum
- brainstem
- midbrain
- pons
- medulla oblongata
Describe the internal structures of the brain: coronal view
- cerebral cortex (grey matter) - the bit around the outside
- White mater (3 types) the axons
- Deep nuclei (collection of cell bodies that are deeper in the brain)
Describe the three types of white matter
- Commissural tracts: axons cross from side to side (eg. corpus callosum) connects the left and right sides of brain in terms of information
- Projection tracts: Axons extend between cortex and other CNS areas outside cerebrum. (eg. corticospinal tract)
- Association tracts: Axons are on same side within cerebral cortex. Communication between brain areas on the same side (can be short or long distances)
What are the major cortical areas for motor control and somatosensory perception?
- Primary motor cortex - pre-central gyrus
- Primary somatosensory cortex - post-central gyrus
Summarise somatic efferent (motor) division
- voluntary movement
- efferent: information flow away from CNS
- two neurons between brain and effector
- upper motor neuron
- lower motor neuron
- axons are myelinated
- neurotransmitter: acetyl choline (ACh)
- effector - skeletal muscle
Describe the primary motor cortex organisation
- The precentrtal gyrus functions as the primary motor cortex
- Specific regions of the motor cortex control specific regions of the body
Describe the corticospinal pathway (the somatic efferent pathway)
- somatic efferent
- two neurons between brain and effector
- Upper motor neuron (neuron #1)
- lower motor neuron (neuron #2)
Upper motor neuron:
1. cell body in the primary motor cortex (pre central gyrus)
2. axon extends from motor cortex to spinal cord on opposite side
3. makes synapse on lower motor neuon
Lower motor neuron:
1. cell body in ventral horn (grey matter) of spinal cord
2. Axon extends out of spinal cord (ventral root) into body
3. Makes synapse on skeletal muscle
What happens when the primary motor cortex is damaged?
muscle weakness and paralysis in region of body corresponding to the location of damage, oppsite side
Describe the primary somatosensory cortex organisation
- the post central gyrus functions as the primary somatosensory cortex
- specific regions of the somatosensory cortex receive sensory information from specific regions of body
Describe the dorsal/posterior column pathway
- Three neurons between sensory receptor (in body) and somatosensory neuron in post central gyrus
Neuron #1:
a. cell body in dorsal root ganglion
b. peripheral fibre (input zone) from sensory receptor in skin
c. central fibre (output zone) ascends towards brain in dorsal columns (spinal cord white matter)
d. makes synapse on neuron #2 in medulla oblongata
Neuron #2:
a. cell body in medulla oblongata
b. axon crosses to opposite side and ascends
c. makes synapse on neuron #3 in thalamus
Neuron #3:
a. cell body in thalamus
b. axon extends to somatosensory cortex
c. makes synapse on cell body of a somatosensory cortex neuron
- perception of light touch on foot
