NA and NP (1) - central NS

Question 1

What do the CNS and PNS consist of?

Answer 1

CNS - Brain and spinal cord (integrating command centre)

PNS - cranial and spinal nerves (communication between CNS and other parts of the body)

Question 2

Within the PNS what are the two subdivisions?

Answer 2

1. Sensory division = somatic and visceral fibers - from receptors TO CNS [receiving info]
2. Motor division = motor nerve fibers - from CNS to effectors [sending info]

Question 3

What are the two subdivisions within the motor division of the PNS?

Answer 3

1. Somatic NS - voluntary from CNS to skeletal muscle
2. Autonomic NS - involuntary (visceral motor/reflexes) from CNS to cardiac muscle, smooth muscle and glands
   [think about not being able to voluntarily control your heart beating]

Question 4

What are the two subdivisions of the autonomic NS ?

Answer 4

Sympathetic division = fight/flight responses (when under stress/emergency reactions)

Parasympathetic = rest/digest - conserving energy at rest (digesting food)

Question 5

What are the subdivisions of the brain (general) ?

Answer 5

Brain stem, cerebellum, cerebral hemispheres, diencephalon

Cerebellum -> anterior, posterior and flocculonodular lobes
Diencephalon -> hypothalamus, thalamus, epithalamus
Brain stem -> midbrain, pons, medulla oblongata

Question 6

Differences between gray matter and white matter?

Answer 6

Gray matter = nonmyelinated and short, some organized into nuclei while others distributed as cortical areas along surface of brain

White matter = primarily myelinated axons, some can be nonmyelinated

Question 7

How would you describe the gray/white matter areas of the spinal cord vs the brain?

Answer 7

Spinal cord - butterfly shape of gray matter on inside surrounding the central cavity, white matter around the oustide

Brain - similar to spinal cord with additional areas of gray matter
*Note for brain; cerebral hemispheres and cerebellum have an outer bark of gray matter

Question 8

Describe the ventricles

Answer 8

Continuous with one another and with central cavity of spinal cord

• Filled with CSF lined by ependymal cells
• Paired lateral ventricles are separated by narrow septum pellucidum (nervous tissue); each communicates with narrow 3rd ventricle in diencephalon via interventricular foramen (a small hole allowing the passing of fluids)
• 3rd connects to 4th ventricle via cerebral aqueduct (dorsal to pons)
• 3 apertures; paired lateral apertures and median aperture, connects ventricles to subarachnoid space which surrounds the brain

Question 9

What are the anatomical landmarks of the cerbral hemispheres?

Answer 9

Sulci (valleys) and Gyri (hills)

Both help the increase the surface area of the brain and help divide it into distinct areas

Question 10

What is a fissure? The 2 notable ones within the cerebal hemispheres?

Answer 10

Fissure = prominent sulci

Longitudinal fissure and transverse cerebral fissure

Longitudinal - separates the cerebral hemispheres
Transverse - separates the cerebellum from the cerebral hemispheres

Question 11

Name some notable sulci/gyri

Answer 11

1. Central sulcus - separates frontal (motor) and parietal (sensory)
2. Precentral/postcentral gyrus - borders the central sulcus
3. Parieto-occipital sulcus - separates parietal and occiptial lobes
4. Lateral sulcus - outlines flaplile temporal lobes and separates from frontal and parietal lobes

Question 12

Describe the cerebral cortex (functions and characteristics)

Answer 12

Composed of gray matter

Allows for conscious voluntary behaviour - perceive, communicate, remember, understand, appreciate

Composed of cells bodies, dendrites, nonmyelinated axons with many convolutions (3x its SA)

Includes Brodmann areas (only used as landmarks)

Question 13

What are Brodmann areas and where can they be found?

Answer 13

Found in cerebral cortex

Have 3 functional areas; sensory, motor, association

Each hemisphere controls the opposite side of the body - contralateral (left brain controls right side of body)

Largely symmetrical but not 100% equal in function (lateralization)

All conscious behaviour involves entire cortex to some degree

Question 14

What are the 4 motor areas? Describe each of them briefly in regards to their functions.

Answer 14

1. Primary motor cortex = contains pyramidal cells (large neurons) that allow for control of skeletal muscle
   - for areas that need finer and more specific and careful innervations of the control of certain muscles (facial muscles)
   - motor innervation is contralateral
2. Premotor cortex = organization of an array of motor responses vs a series of single motor responses
   - helps PLAN movements
   - coordinates movements of several muscles simultaneously (muscle memory)
   - can control voluntary actions that depend on sensory feedback (making changes or adjustments to your plan)
3. Broca’s area (region BA 44) = present only in 1 hemisphere (usually associated with language)
   - active when we prepare to speak and during motor speech
   - when planning or organizing making sounds as words
4. Frontal eye fields = controls voluntary movement of the eyes
   - controls looking up and down and side to side

Question 15

What are the main sensory areas?

Answer 15

1. Primary somatosensory cortex (PSC) = receives info from somativ sensory receptors (skin) and proprioceptors (joints/muscles), also includes spatial discrimination
   - Knowing where your different body parts are in space and time
2. Somatorsensory association cortex = connections with PSC to integrate and analyze somatic inputs (temperature/pressure) and to interpret the size, texture, relationship of parts based on prior experience

Question 16

What are the sensory visual areas?

Answer 16

1. Primary visual cortex (PVC) = contains map of visual space on retine (contralateral) - only recieves the visual info
2. Visual association area = Surrounds PVC, interprets visual image based on prior experience/knowledge - making links with memory and things learned based on what is being seen

Question 17

What are the sensory auditory areas?

Answer 17

1. Primary auditory cortex = receives the physical aspect of sounds - pitch, loudness, rhythm
2. Auditory association areas = interpretation of the sounds based on memory or prior experience (speech/music/words/understanding when someone is speaking to you)

Question 18

What are the sensory olfactory areas?

Answer 18

Olfactory cortex = conscious awareness of different odours
- medial aspects of temporal lobes = uncus
- not as prominent in humans, most of the tissue has developped into the limbic system; this is why certain odours are linked to certain emotions/memories

Question 19

What are the sensory gustatory areas?

Answer 19

Gustatory cortex = awareness of different tastes; insula receives taste info (sweet/salty/bitter/umami/sour)

Question 20

What are the sensory visceral areas?

Answer 20

Visceral sensory area = awareness of bladder being full/feeling nauseous - usually not aware of it until you need to carry out a response (going to the washroom)

Contains multimodal association areas = receiving info from multiple senses and sending output to multiple areas

Question 21

What are te 4 sensory areas not a part of the 5 main senses?

Answer 21

1. Vestibular (equilibrium) cortex = awareness and coordination of posture and balance
2. Anterior association areas = the most complicated cortical area; linked with intellect, complex learning (cognition), recalling, personality, abstract ideas, judgement, persistence, planning, concern, conscience
   - Matures slowly because it is dependant on social environment feedback (learning how to behave or react appropriately in certain situations)
3. Posterior association areas = input from all sensory association areas - the storage of complex memories
   - puts all the info together to understand what is being seen, felt…
   - some parts for understanding spoken and written languages = Wernickes area
4. Limbic association areas = puts emotional value on experiences
   - provides emotional impact; being aware of the possible danger associated with a particular situation based on prior experience/learning)
   - Should I be happy in this situation? Sad? Angry? …

Question 22

What is the result of damage to the primary visual cortex? The visual association area?

Answer 22

If the primary visual cortex is damaged, you would not be able to see or have vision

If the visual association area is damaged, you can still see (vision is intact) but you are not able to interpret or understand what is being seen

Question 23

Cerebal dominance?

Answer 23

the hemisphere that is dominant for language
- usually the left hemisphere in most people

Question 24

What fibers are found in cerebral white matter?

Answer 24

1. Commissural fibers = connect corresponding areas between the 2 hemispheres (largest is corpus callosum)
2. Association fibers = connections within a hemisphere (connecting gyri/lobes)
3. Projection fibers = connections to and from the cortex to the rest of the NS (the only ones which run vertically)

Question 25

What are basal nuclei? functions? important regions within it?

Answer 25

Involved in the control of movement

No direct access to motor pathways; do not directly stimulate muscle movement, uses areas of integrating info.

Role in starting/stopping/monitoring intensity of movements; inhibits antagonistic or unnecessary action through filtering

Caudate (anterior)
Putamen (lateral)
Globus pallidus (medial)

Question 26

What is the thalamus? what is it composed of and what are its functions?

Answer 26

2 masses of gray matter help together by the midline commissure (interthalamic adhesion)

Afferent impulses from all senses and parts of the body converge on the thalamus

Gateway to the cerebral cortex (sends correct info the the correct areas of the brain)

Majority of info goes through the thalamus to get directed to the right place to be understood, aware of, analyzed or interpreted

Question 27

What is the hypothalamus? What are its main functions (7)?

Answer 27

Where the NS and endocrine system come together - sits below the thalamus

1) Autonomic control centre - BP, heart, GI, respiration
2) Centre for emotional response and behaviour - heart of the limbic system
3) Body temperature regulation
4) Regulation of food intake - hunger or satiety
5) Regulation of water balance and thirst - release of ADH for salt/water balance
6) Regulation of sleep/awake cycles - suprachiasmatic nucleus (SCN) for release of melatonin
7) Control of endocrine system - production of ADH and oxytocin

Question 28

What is the epithalamus?

Answer 28

the most dorsal part of the diencephalon

extension of the pineal gland which releases melatonin - sleep inducing

includes choroid plexuses - a CSF forming structure