CNS Flashcards
Organisation of CNS, general & modified
• Fluid filled core -> Gray matter -> White matter
• Organization is modified in cerebellum and cerebrum
o Fluid filled core -> gray matter -> white matter w/ islands of gray matter (nuclei) -> gray matter (cerebral cortex)
Structures of lateral ventricles and what separates them
a. Structures: anterior horn, posterior horn, inferior horn
b. R & L separated by septum pellucidum
Location of third ventricle and what separates it
a. Inferior to lateral ventricles, separated from lateral ventricles by interventricular foramen
Location of fourth ventricle and what separates it
a. Inferior to third ventricle, separated by cerebral aqueduct
Where does CSP drain from the ventricles
- CSF produced in all ventricles drains downward. Once it reaches 4th ventricle it either drains through the central canal down the spinal cord, or through the medial and lateral apertures to surround brain itself.
Convolutions
Hills and valleys of cerebral hemispheres
Gyros
Elevated ridge
Sulcus
Depression/valley
Precentral gyrus
in front of central sulcus
Post central gyrus
behind central sulcus
Central sulcus
separates frontal & parietal lobe
Parietal-occipital sulcus
separates occipital from parietal lobe
Lateral sulcus
separates temporal from parietal & frontal lobe
Fissure
Very deep sulcus
Longitudinal fissure
divides R & L hemispheres
Transverse fissure
divides cerebrum from cerebellum
Layers of cerebrum
a. Cortex: outer, top part of brain. Has the most complex features necessary for abstract thought, intelligence, etc. Made from gray matter.
b. White matter: myelinated fibers
c. Basal nuclei: islands of gray matter in the white matter
How thick is cerebral cortex and how many percent of brain mass
a. Only a few mm thick but makes up 40% of brain mass due to convolutions
Functions of cerebral cortex
sensation, communication, memory, understanding, voluntary movement
Name 12 broadman areas
Primary motor cortex Premotor cortex Frontal eye field Broca’s area Primary somatosensory cortex Somatosensory association cortex Primary visual cortex Visual association area Primary auditory cortex Auditory association area Olfactory cortex Gustatory cortex
Primary motor cortex
- Allows for voluntary movement
- Located in precentral gyrus
- Contains pyramidal cells and tracts that are a special type of neuron traveling to skeletal muscle, also referred to as corticospinal
Premotor cortex
- Located anterior to primary motor cortex
- Borrows neurons from primary motor cortex
- Controls learned or rhythmic repetitive movement, ex. Typing, playing instrument
Frontal eye field
- Located anterior to premotor complex
2. Controls voluntary eye movement
Broca’s area
- Directs speech—not just ability to phonate but also coordinate tongue, jaw, lip movements etc.
- Also activates when thinking about speaking
Primary somatosensory cortex
- Located on postcentral gyrus
- Receives impulses from skin and skeletal muscles
- Plays role in spatial discrimination
vi. Somatosensory association cortex
- Interprets more of the sensory impulses and spatial discrimination than primary SSC can
Primary visual cortex
- Picks up general characteristics of an object that you see, e.g. “green tall thing narrow at the top”
Visual association area
- Matches impulses w prior experiences and interprets the information to figure out what it is, e.g. “it’s a tree”. Or more specific, “it’s a doug fir”
Primary auditory cortex
- Picks up pitch, rhythm, loudness
Auditory association area
- Allows interpretation—“it’s music”, “it’s bruce springsteen”
Olfactory cortex
- Input from olfactory receptors—smell
2. Doesn’t really have an association area, instead has associations w hypothalamus and limbic system
Gustatory cortex
- Taste, does not have association area
Homunculus
i. Distorted image of body representing neurological map, which neurons go to which part of the body
ii. Size of body part indicates the number of nerves going to that body part, and as such the level of specificity in movement or sensation
iii. Body parts that work closely together are next to each other on the homunculus
iv. There is one for motor function in precentral gyrus and one for somatosensory in post central gyrus
Multimodal association area
i. Where all the sensory areas communicate w each other, interpreting impulses from multiple senses at once
Anterior multimodal association area
- Located in frontal lobe, prefrontal cortex
2. Personality, intellect, complex/abstract thought, learning, conscience, judgment
Posterior multimodal association area
- Recognition of patterns and faces
- Wernicke’s area: written & spoken language understanding—opposite of Broca’s area
- Binding different sensory input into an understanding of coherent story & bigger picture
Fiber tracts/white matter in cerebrum: types of fiber
Commisural fibers
Association fibers
