The Central Nervous System Flashcards
What is a nerve?
A combination of axons/ fibres outside of the CNS
What is a tract?
A group of myelinated axons that travel together within the CNS and share a common origin, destination and function.
What is grey matter?
A number of cell bodies that are grouped together which appear grey.
Why is white matter white.
It appears white due to the presence of myelin.
What is a nucleus or nuclei?
A group of neuronal cell bodies located in the same area and sharing the same function within the CNS.
What is a ganglion or ganglia?
They are similar to nuclei, they are a group of neuronal cell bodies, but they are found outside the CNS as a discreet swelling.
What direction do afferent fibres go?
Afferent fibres carry impulses towards the CNS or higher centres.
Normally sensory signals.
What direction do efferent fibres go?
Efferent fibres carry impulses away from the CNS or higher centres.
Normally motor signals.
What are some features of the spinal cord?
Rostrally continuous with the brain stem
Extends from the foremen magnum to L1-L2 in adults
Vertebral foramen
Ends at the conus medullaris
Cauda equine
Surrounded by dura
Cervical and lumbosacral enlargements
What are the three beginning stages of brain development?
Prosencephalon
Mesencephalon
Rhombencephalon
What is the next stage in development from the prosencephalon?
Telencephalon
Diencephalon
What structure develops from the mesencephalon?
The midbrain
What the next stage of development from rhombencephalon?
Metencephalon
Myelencephalon
What structures develop from the telencephalon?
The cerebral hemispheres.
Why structures develop from the diencephalon?
Thalamus
Hypothalamus
Subthalamus
What structures develop from the metencephalon?
Pons
Cerebellum
What structure develops from the myelencephalon?
The medulla.
What are the three distinctions of brain anatomy?
Forebrain
Midbrain
Hindbrain
Which of the secondary stages of brain development are found in the forebrain?
Telencephalon
Diencephalon
Which one of the secondary stages of brain development is found in the midbrain?
Mesencephalon
Which of the secondary stages of brain development are found in the hindbrain?
Metencephalon
Myelencephalon
What is a sulcus or sulci?
They are the depressions or grooves between the ridges of the cerebral hemispheres.
What is a gyrus or gyri?
They are the folds or ridges that can be seen in the folding appearance of the cerebral hemispheres.
If a species has more sulci and gyri what might this be an indicator of?
If there is a higher frequency of gyri and sulci it can indicate higher level of intelligence.
What are the four lines of the cerebrum?
Frontal
Parietal
Occipital
Temporal
What are the landmark sulci to look out for to orientate the brain?
Central sulcus
Lateral sulcus
What is the name given to the line dividing the two hemispheres?
Longitudinal cerebral fissure
Give an example of an area/section of the brain that is not mirrored in both hemispheres.
Broca’s area
Wernicke’s area
Both found on the LHS of the brain
List some features of the frontal lobe.
Largest lobe of the brain
Location of the pre central gyrus - primary motor areas are housed
Regulates voluntary motor behaviour as well as initiating it
Broca’s area is located on the lateral surface
Where is Broca’s area found?
The inferior lateral aspect of the frontal gyrus
What is Broca’s aphasia?
Difficulty generating written or spoken language
Still maintain language comprehension
List some features of the prefrontal area of the brain.
Electrical stimulation does not elicit movement
Extensive connections with parietal, occipital and temporal lobes via fasiculi
Monitors behaviours and controls higher processes (judgement)
Prefrontal association areas concerned with emotion, motivation, personality, initiative, judgement, concentration and social inhibitions.
What was a prefrontal lobotomy?
Surgical intervention to separate the prefrontal cortex from the rest of the frontal lobe and thalamus for treatment of neuropsychiatric disorders.
List some features of the parietal lobe.
Regulates somatosensory functions
Location of the post central gyrus - primary somatosensory area is housed
Initial cortical processing and perception of pain, temperature and proprioception
Houses Wernickes area
Concerned with spatial awareness
Where is Wernickes are located?
The superior temporal gyrus.
Describe Wernickes aphasia.
Difficulty understanding written or spoken language
Can generate speech but the language is meaningless - unconnected words
List the features of the occipital lobe.
Involved in processing visual information
Visual association areas surround and cover the lateral surface of this lobe
Separated from the parietal lobe by the parieto-occipital sulcus
Separated from the temporal lobe by the calcarine sulcus
List the features of the temporal lobe.
Processes auditory information
Superior temporal gyrus - where our ability to hear and interpret what’s we hear
Lateral surface functions for the perception of language
Anterior medial areas - complex aspects of memory, learning and emotion
What separates the occipital lobe from the parietal lobe?
Parieto-occipital sulcus
What separates the occipital lobe and the temporal lobe?
The calcarine sulcus
Which side of the brain is dominant in most people?
The left hand side
Thought to be more practical, compared to the right hand side being more creative
What does the left hemisphere control?
Reading
Writing
Decision making
Speech
Language
What aspects does the right hemisphere control?
Senses (touch, smell, sight, tastes, feel)
Recognition (faces, voice inflections)
What connects the two hemispheres together?
The corpus callosum
What do white fibres in the brain do?
Relay information to and from specific areas.
What are the two types of white fibres?
Short association fibres
- connect areas in adj gyri (1/2 sulci)
Long association fibres
- fasiculi - connect areas further apart - cross more than two sulci
What are commissural fibres?
They are a form of white fibre, they cross the midline to connect areas of the cortex in one hemisphere with the same area in the opposite hemisphere.
Enables coordination of activity between two hemispheres.
What is the corpus callosum made up of?
White fibres - commissural fibres
What is split brain syndrome?
Lesions in the corpus callosum as a result of traumatic injury or surgical intervention.
Loss of interhemispheric transfer of information, loss of coordination between right and left hands
What is neuroplasticity?
The ability of neural networks in the brain to change through growth and reorganisation. The brain is required to function in a way different to how it previously functioned.
What are projection fibres?
They travel to or from the
Cortex
Thalamus or
Descend through the:
Basal nuclei
Brainstem or
Spinal cord
What are the three types of cortical areas?
Motor
Sensory
Association (75% of the total surface of the cerebral cortex)
What are Brodmann’s areas?
52 areas defined by differences in neuronal cellular structure.
Later discovered that there was a correlation with cortical function within each area.
List the features of the cerebrum.
Located under the cortical layer
Contains cell bodies and white matter tracts that connect various parts of the brain to one another
Gray matter nuclei which the basal nuclei and limbic system contribute
What are basal nuclei?
Group of interconnecting nuclei with the forebrain, Diencephalon and midbrain.
The initiation and control of voluntary movement.
Includes caudate, lenticular nuclei, subthalamic nucleus and substantia nigra.
What is the limbic system?
Interconnected and interacting structures that play a significant role in drive related and emotional behaviours. There is also a role in memory and learning.
Describe the diencephalon.
It consists of several sets of paired structures on either side of the 3rd ventricle.
List the structures within the diencephalon.
Thalamus (largest)
Hypothalamus
Pineal body
Habenular nucleus
Posterior pituitary gland
What is the thalamus?
A sensory switchboard
All sense signals except smell go through the thalamus
What does the hypothalamus do?
Controls
Homeostatic
Autonomic and
Endocrine functions
What does the pineal body do?
Produces melatonin and maintains circadian rhythms
List the features of the midbrain.
Pair of cerebral peduncles
Important linkage between components of motor system (the cerebellum, basal nuclei and cerebral hemispheres)
Contains the substantia nigra, superior and inferior colliculi and the red nucleus
What is the hindbrain composed of?
The pons, medulla oblongata and cerebellum
List the features of the pons.
Carries information from the pontine nuclei to the cerebellum.
Involved in:
-respiration
-taste
-sleep
List the features of the medulla oblongata.
It merged with the spinal cord.
Corticospinal fibres descend in pyramids on its anterior surface
Houses the olivary nuclear complex
Sensory tract fasiculus gracilis and cunaeatus on posterior aspect
List the features of the cerebellum.
An outgrowth of the pons
Outer surface is covered by the cerebellar cortex
Has two hemispheres and a central area known as the vermis
Contains a greater number of neurones than any other subdivision although very few neuronal types
How is the cerebellum connected to the brainstem?
By the cerebellar peduncles.
Sensory info from spinal cord
Motor info from cerebral cortex
Input about balance from vestibular apparatus in the inner ear.
What does the cerebellum do?
Maintaining posture and coordinating head and eye movement
Fine tuning muscle movements
Helps when learning motor skills
Also involved in language and other cognitive functions
