lecture 22 - movement & sensation Flashcards
What are the major sulci/fissures of the brain (4)?
Central, lateral and parietal-occipital sulcus, transverse fissure
What parts of the brain does the central sulcus divide?
Frontal and Parietal lobes
What parts of the brain does the lateral sulcus divide?
Frontal and temporal lobe
What parts of the brain does the parieto-occipital sulcus divide?
Parietal and occipital lobes.
What parts of the brain does the transverse fissure divide?
The cerebellum from the temporal and occipital lobes.
What are the functions of the frontal lobe?
Motor control (top) & language and personality (bottom)
What are the functions of the temporal lobe?
Memory and hearing
What are the functions of the parietal lobe?
Somatosensory
What are the functions of the occipital lobe?
Vision (contains visual cortex)
What is the diencephalon?
Small part within the centre of the brain, that contains the thalamus and hypothalamus.
What is the corpus callosum?
A bundle of nerve fibres (myelinated axons) that connect the two hemispheres of the brain.
What is the colour of the corpus callosum, and why is it this colour?
White - contains fat, in the form of myelin on the axons bound with oligodendrocytes.
Where is the cerebellum located?
At the bottom/back of the brain.
Where does the brain stem attach to the rest of the brain?
At the thalamus (of the diencephalon)
What are the parts of the brain stem, from superior to inferior?
Midbrain, pons, medulla oblongata
Where does the brain stem connect to the spinal cord?
Through the foramen magnum to the medulla oblongata
What is the structure and appearance for the cerebral cortex?
Made up of cell bodies (grey matter)
What is white matter?
Tracts of myelinated axons within the brain.
What are the 3 types of white matter?
Commissural, projection and association tracts.
What are commissural tracts?
Bundles of axons that cross from 1 hemisphere of the brain to the other.
The corpus callosum is an example of which type of tracts?
Commissural tracts.
What are projection tracts?
Tracts of axons that extend between the cortex and other CNS areas outside of the cerebrum. (e.g. corticospinal tract)
What type of tract is the corticospinal tract?
A projection tract
What does. the corticospinal tract connect?
The cerebral cortex to the spinal cord.
What are association tracts?
Tracts of axons that connect parts of the cerebral cortex in the same hemisphere. Allows for short or long distance communication.
What part of the brain functions as the primary motor cortex?
Pre-central gyrus.
What is the location of the pre-central gyrus?
Adjacent to the central sulcus, in the frontal lobe.
What is the pre-central gyrus made up of?
Cell bodies of upper motor neurons that form somatic efferent pathways.
How does the primary motor cortex control movement?
Specific regions of the motor cortex control specific regions of the body, with more neurons for more delicately controlled body parts.
What is the overall pathway for information in somatic efferent motor control?
Upper to lower motor neuron, then to effector (skeletal muscle).
Where is the cell body on an upper motor neuron of the somatic efferent pathway found?
In the primary motor cortex/pre central gyrus.
What is the pathway of the axon of the upper motor neuron in a somatic efferent pathway?
Extends from motor cortex to spinal cord, crossing over (usually at the medulla oblongata) to the opposite side of the cord before synapsing with the lower motor neuron.
Where is the cell body of a lower motor neuron in a somatic efferent pathway?
Ventral horn (grey matter) of spinal cord, on opposite side to the original motor neuron’s origin in the primary motor cortex.
What is the pathway of the axon of the lower motor neuron in the somatic efferent pathway?
Extends out of ventral root of the spinal cord into the body where it makes a synapse on skeletal muscle.
What structure of the brain is associated with somatosensory perception?
Post-central gyrus
What is somatosensory perception?
Conscious perception of touch, pressure, temperature, etc.
What is the location of the post-central gyrus?
On the parietal lobe, adjacent to the central sulcus.
Where is the primary somatosensory cortex?
At the post-central gyrus
How many neurons are in the dorsal column pathway?
3
What does the dorsal column pathway control?
Somatosensory perception
Where is the first neuron in the dorsal column pathway?
Input zone at sensory receptors, cell body in dorsal root ganglion, output zone ascends the brain stem (dorsal column) to make synapse with neuron 2 in medulla oblongata.
What class of neuron (—polar) is the 1st neuron in the dorsal column pathway?
Unipolar
What are the locations of the 2nd neuron in dorsal column pathway?
Cell body in medulla oblongata, axon crosses to opposite side of spinal cord and makes synapse to neuron 3 at thalamus
What are the locations of the components of Neuron 3 in the dorsal column pathway?
Cell body in thalamus, axon ascends to somatosensory cortex, makes synapse to cell body of somatosensory neuron for touch to be perceived.
What is a motor unit?
A unit consisting of a motor neuron and all the muscle fibres it innervates.
How many muscle fibres can a single motor neuron synapse with?
Up to a few thousand
What is the structure of a small motor unit?
Consists of one motor neuron and a few dozen muscle fibres
what is the structure of a large motor unit?
Single motor neuron and as many as a few thousand muscle fibres
What does the corticospinal/pyramidal tract control?
The control of precise,voluntary movements
