Central Nervous System Part I Study Guide Flashcards
two structures that make up the central nervous system
brain and spinal cord
What are the 4 main regions of the human adult brain?
Cerebrum (2 hemispheres)
Diencephalon
Brain stem (midbrain, pons, medulla oblongata)
Cerebellum
gray matter
short, unmyelinated neurons + cell bodies
white matter
mostly myelinated axons, some unmyelinated axons, primarily organized in fiber tracts
basic pattern of the CNS
central cavity surrounded by gray matter with white matter external to the gray matter – this pattern is seen in the spinal cord
How does the basic pattern of the CNS differ in the brainstem?
Brainstem has additional gray matter nuclei scattered within the white matter
How does the basic pattern of the CNS differ in the cerebral cortex?
The cerebral hemispheres and cerebellum contain an outer layer of gray matter (the cortex)
Ventricles
fluid filled chambers continuous with one another and with the central canal of the spinal cord
what do ventricles contain
cerebrospinal fluid (CSF)
what are ventricles lined with
ependymal cells
What divides the paired, lateral ventricles?
Septum pellucidum (thin membrane)
What structure connects the paired lateral ventricles with the 3rd ventricle?
Interventricular foramen
Name the 3 openings that connect the 4th ventricle to the subarachnoid space.
Paired lateral apertures, 1 median aperture
Gyri
ridges
sulci
shallow grooves
fissures
deep grooves
longitudinal fissure
separates the 2 hemipsheres
transverse cerebral fissure
separates the cerebrum and cerebellum
5 lobes of the cerebral hemisphere
Frontal
Parietal
Temporal
Occipital
insula
functions of the cerebral cortex
- The executive suite of the brain
- Thin (2-4mm) superficial layer of gray matter
- Site of the conscious mind: awareness, sensory perception, initiation of voluntary motor tasks, communication, memory storage, understanding
- Composed of neuron cell bodies, dendrites, glial cells, and blood vessels – no axons
- Contains billions of neurons and accounts for 40% of brain mass
3 types of functional areas within the cerebral cortex
- Motor areas: control voluntary movement
- Sensory areas: conscious awareness of sensation
- Association areas: integrate diverse information
domain
- The place a particular motor or sensory function is localized
- The higher functions (memory, language, etc) are spread over multiple areas and in overlapping domains
contralateral
Each hemisphere is chiefly concerned with the sensory and motor functions of the contralateral (opposite) side of the body
Lateralization
specialization of cortical function in only one hemisphere
Premotor cortex
- Helps to plan movements – a staging area
- Selects + sequences basic motor movements into more complex tasks
- Uses highly processed sensory information to control voluntary actions
- Sends activating impulses to the primary motor cortex
Broca’s area
- Present in only 1 hemisphere – usually the left
- Motor speech area – directs the muscles of speech production
- Active in planning speech and other voluntary motor activities
Frontal eye field
- Located partially in and anterior to the premotor cortex
- Controls voluntary eye movements
Pyramidal cells
large neurons that allow conscious control of precise, skilled skeletal muscle movements
pyramidal (corticospinal) tracts
formed from the long axons of the pyramidal cells that project down to the spinal cord
Somatotopy
all specific areas of the body can be mapped to specific areas on the primary motor cortex
Motor homunculi
upside down, caricature like representation of the motor innervation of the contralateral body regions
symptoms of primary motor cortex damage
- Paralyzes the muscles controlled by those areas
- Paralysis will occur on the opposite side of the body from the cortical damage
- Only voluntary control is lost – the muscles can still contract reflexively
damage to the premotor cortex
- loss of the motor skills programmed by that region, but does not impair muscle strength or ability to perform discrete, individual movements
- Other premotor neurons can be reprogrammed to take over the skill of the damaged neurons, but this requires significant patience and practice
motor and sensory homunculi: Which areas have a lot of representation? Which areas only have a little?
The hands, fingers, face, and tongue have large representation
Legs and back have less representation
Primary somatosensory cortex
- Receives general sensory information from skin and proprioceptors of skeletal muscles, joints, and tendons
- Capable of spatial discrimination: identification of body region being stimulated
Somatosensory association cortex
Integrates sensory inputs relayed to it from primary somatosensory cortex to provide an understanding of an object being felt – determines size, texture, and relationship of parts
Primary visual (striate) cortex
- Largest cortical sensory area
- Receives visual information that originates on the retinas
- The visual space on the opposite side of the body is mapped to the primary visual cortex
Visual association area
- Uses past visual experiences to interpret visual stimuli (color, form, or movement) ex. ability to recognize faces
Primary auditory cortex
Interprets information from the sound receptors in the inner ear – determines pitch, loudness, and location
auditory association area
Stores memory of sounds, permits perception of the sound stimulus
Vestibular cortex
Responsible for conscious awareness of balance (position of the head in space)
Primary olfactory cortex
- Part of the primitive rhinencephalon – along with the olfactory bulbs and tracts. In humans, the remainder of the rhinencephalon becomes part of the limbic system
- Involved in conscious awareness of odors
- Receives impulses from the superior nasal cavity
Gustatory cortex
in the insula – deep to the temporal lobe
- Involved in perceiving taste stimuli
Visceral sensory area
posterior to the gustatory cortex
- Provides conscious perception of visceral sensations – ex. Upset stomach or full bladder
functional blindess
- Damage to the primary visual cortex
- Although unable to consciously see, individuals with functional blindness may still have certain visual reflexes
face blindness
Damage to the visual association area results in ability to see but inability to comprehend what is seen
3 multimodal association areas
Anterior association area
Posterior association area
Limbic association area
Multimodal association area
receives inputs from multiple sensory areas and send outputs to multiple areas
- Allow us to give meaning to information received, store information in memory, tie information to previous experiences, and decide on actions
- Where sensations, thoughts, and emotions become conscious – and make us who we are
Anterior association area
- Also called the prefrontal cortex
- The most complicated cortical region
- Involved in intellect, cognition, recall, and personality
- Contains the working memory needed for abstract ideas, judgment, reasoning, persistence, and planning
- Development happens slowly and depends on feedback from social environments
Posterior association area
- Large region including parts of the temporal, parietal, and occipital lobes
- Plays a role in recognizing patterns, faces, and localizing the body within space
- Involved in understanding written and spoken language (wernicke’s area)
Limbic association area
- Involves the cingulate gyrus, parahippocampal gyrus, and hippocampus
- Provides the emotional impact that makes a scene important to us – and helps us to establish memories
symptoms of disruption in the posterior association area
disassociating with the other half of the body – the half opposite the side of the lesion
symptoms of disruption in the anterior association area
mental and/or personality disorders including loss of judgment, attentiveness, and inhibitions
- Affected individual may be oblivious to social restraints or become careless about personal appearance and/or taking risks
Most humans are _____ side dominant. This means that most humans are ______ handed.
left
right
cerebral dominance
refers to which hemisphere is dominant for language
Left hemisphere
Controls language, math, and logic
Right hemisphere
visual spatial skills, intuition, emotion, artistic and musical skills
Cerebral white matter is mostly bundled into large _______.
tracts
which direction do association fibers run?
horizontal
what kind of communication are association fibers responsible for?
Connecting different parts of the same hemisphere
Which direction do commissural fibers run
horizontal
What kind of communication are commissural fibers responsible for?
Connect corresponding gray matter of the two hemispheres
What is the largest of the commissural fiber tracts?
Corpus callosum
Which direction do projection fibers run
vertical
What kind of communication are projection fibers responsible for?
Connect the hemispheres with the lower brain or spinal cord
internal capsule
projection fibers on each side of the brain stem form a compact band that passes between the thalamus and some of the basal nuclei
Corona radiata
projection fibers that fan out and radiate through the cerebral white matter to the cortex
The striatum is made of the _______________ + the ________.
audate nucleus
putamen
List 3 specific parts of the basal nuclei/basal ganglia.
Caudate nucleus
Putamen
Globus pallidus
What are some functions of the basal nuclei? How does these functions correlate with the symptoms of Parkinson Disease?
Basal nuclei receive input from the entire cerebral cortex and relay it through the thalamus. The output is projected to premotor and prefrontal cortices to influence muscle movements
- Plays roles in motor function, emotion, and cognition
- Is especially useful in starting, stopping, and monitoring the intensity of relatively slow or stereotyped movements
- Also inhibits antagonistic or unnecessary movements
* When someone has parkinsons, they often make many uncontrolled and unnecessary movements
What is the likely cause of Parkinson disease
Degeneration of the dopamine-releasing neurons in the substantia nigra
- Dopamine deprived basal nuclei become overactive
What is a medication that can temporarily alleviate Parkinsonian symptoms?
Medication L-dopa can alleviate symptoms temporarily
