1. Chapter 8 Nervous System
CNS Structure:
Brain = within cranial cavity:
Control center for many body functions
Consists of cerebrum, diencephalon, brainstem, & cerebellum

2. Brain Regions
Cerebrum
Diencephalon
Cerebellum
Brainstem
Cerebellum

3. Brain Cerebrum - part which most people consider brain (largest)
- divided into 2 hemispheres (left & right) connected by corpus callosum

4. Brain

5. Brain

6. Gray and White Matter Microscopically, CNS contains 2 neural elements:
Neuron cell bodies (clusters are known as nuclei)
Nerve fibers (axons) in bundles called tracts.
Microscopically, CNS tissues can be distinguished by color:
Gray matter consists of soma, dendrites, and unmyelinated axons.
White matter consists primarily of myelinated axons.

7. Brain Cerebrum-w/o a microscope - consists of outer cortex
gray in color (ie cerebral cortex)
-inner portion = white

8. Brain Cerebral Cortex = gray matter
- numerous folds (bumps) called gyri or convolutions
- 2 types of groves
a. deep grooves = fissures
(e.g. longitudinal fissure)
b. shallow grooves = sulci

9. Deeper grooves called fissures separate large regions of the brain.
The median longitudinal fissure separates the cerebral hemispheres.
The transverse fissure separates the cerebral hemispheres from the cerebellum below.
Deep sulci and the lateral fissure divide each hemisphere into lobes:
Frontal, Parietal, Temporal, and Insula. The occipital lobe is not distinctly separate from the other lobes by a sulci.
Why/How are the 1st 4 named?
What does “insular” mean?

10. The central sulcus separates the frontal lobe from the parietal lobe.
Bordering the central sulcus are 2 important gyri, the precentral gyrus and the postcentral gyrus.
The lateral fissure outlines the temporal lobe.
The insula is buried deep within the lateral fissure.
Lobes of the Cerebrum

11. Brain Cerebral Cortex = gray matter
- divided into 4 lobes (named after cranial bones) each with various function(s).

12. Brain Cerebral Cortex = lobes
- frontal lobe = voluntary motor function (skeletal muscles), higher intellectual processes (planning, decisions),

13. Brain Cerebral Cortex = lobes
- parietal lobe = receiving & evaluating cutaneous sensations from skin (taste sensation)

14. Brain Cerebral Cortex = lobes
- temporal lobe = receiving & evaluating auditory (hearing) sensations, smell & short term memory

15. Brain Cerebral Cortex = lobes
- occipital lobe = receiving & evaluating visual sensations (seeing).

16. Brain

17. Brain
Cerebrum = inner white matter consists of nerve tracts with masses of gray matter (groups of cell bodies called nuclei)
-outermost thin layer of gray matter-cerebral cortex
- insula = 5th brain region (memory)

18. Cerebrum
Comprised of 2 cerebral hemisphere and each can be divided into 3 regions:
Superficial cortex of gray matter
Internal white matter
The basal nuclei – islands of gray matter found deep within the white matter

19. Cerebral Cortex
Allows for sensation, voluntary movement, self-awareness, communication, recognition, and more.
Gray matter! 40% of brain mass, but only 2-3 mm thick.
Each cerebral hemisphere is concerned with the sensory and motor functions of the opposite side (i.e. contralateral side) of the body.

20. Cerebral Cortex 3 types of functional areas:
Motor Control voluntary motor functions
Sensory Allow for conscious recognition of stimuli
Association Integration

21. Cortical Motor Areas Primary Motor Cortex Premotor Cortex Broca’s Area
Frontal Eye Field

22. Primary motor cortex
Premotor cortex
Frontal Eye Field
Broca’s Area

23. Primary (Somatic) Motor Cortex
Located in the precentral gyrus of each cerebral hemisphere.
Contains large neurons (pyramidal cells) which project to SC neurons which eventually synapse on skeletal muscles
Allowing for voluntary motor control.
These pathways are known as the corticospinal tracts or pyramidal tracts.

24. Premotor Cortex Located just anterior to the primary motor cortex.
Involved in learned or patterned skills.
Involved in planning movements.
How would damage to the primary motor cortex differ from damage to the premotor cortex?

25. Broca’s Area
Typically found in only one hemisphere (often the left), anterior to the inferior portion of the premotor cortex.
Directs muscles of tongue, lips, and throat that are used in speech production.
Involved in planning speech production and possibly planning other activities.

26. Frontal Eye Field Controls voluntary eye movements.
Found in and anterior to the premotor cortex, superior to Broca’s area.
What muscles would be affected if this area was damaged?

27. Sensory Areas Found in the parietal, occipital, and temporal lobes.
Primary somatosensory cortex
Somatosensory association cortex
Visual areas
Auditory areas
Olfactory cortex
Gustatory cortex
Vestibular cortex

28. Primary Somatosensory Cortex
Found in the postcentral gyrus.
Neurons in this cortical area receive info from sensory neurons in the skin and from proprioceptors, which monitor joint position.
Contralateral input.
What does “somato” mean?
How was the motor somatotopic map arranged?
Do you think the somatotopic map will be identical?

29. Somatosensory Association Cortex
Found posterior to the primary somatosensory cortex and is neurally tied to it.
Synthesizes multiple sensory inputs to create a complete comprehension of the object being felt.
How would damage to this area differ from damage to the primary somatosensory cortex?

30. Primary Visual Cortex
Found in the posterior and medial occipital lobe.
Largest of the sensory cortices.
Contralateral input.
What does this suggest?

31. Visual Association Area
Surrounds the primary visual cortex.
Basically vision is the sensation of “packets” of light on our retinal cells. The primary visual cortex tells which cells are being stimulated and the association area lets us “see” what we’re looking at.

32. Auditory Cortex
Found in the superior margin of the temporal lobe, next to the lateral fissure.
Sound waves excite cochlear receptors in the inner ear, which send info to the auditory cortex.
The auditory association area allows for interpretation and remembering sounds.

33. Olfactory Cortex Found in the frontal lobe just above the orbits.
Receptors in the olfactory epithelium extend through the cribriform plate and are excited by the binding of oderants. They then send their info to the olfactory cortex.
Very much involved in memory and emotion.

35. Gustatory and Vestibular Cortices
Gustatory cortex is involved in taste and is in the parietal lobe just deep to the temporal lobe.
Vestibular cortex is involved in balance and equilibrium and is in the posterior insula

37. Association Areas Allows for analysis of sensory input.
Prefrontal cortex
Language areas
General interpretation area
Visceral association area
Multiple inputs and outputs. Why?

38. Prefrontal Cortex Anterior frontal lobes Involved in analysis,
cognition, thinking, personality, conscience, & much more.
Look at its evolution
What would a frontal lobotomy result in?

39. Language Areas
Large area for language understanding and production surrounding the lateral fissure in the left (language-dominant) hemisphere
Includes:
Wernicke’s area  understanding oral/written words
Broca’s area  speech production
Lateral prefrontal cortex  language comprehension and complex word analysis
Lateral and ventral temporal cortex  integrates visual and auditory stimulate

40. Cerebral White Matter 3 types of fibers:
Commissural – connect corresponding areas of the 2 hemispheres. Largest is the corpus callosum.
Association fibers – connect different parts of the same hemisphere
Projection fibers – fibers entering and leaving the cerebral hemispheres from/to lower structures
Is white matter involved in communication?

42. Basal Nuclei
Set of nuclei deep within the white matter. Collectively called the corpus striatum.
Includes the:
Caudate Nucleus
Lentiform Nucleus
Globus pallidus
Putamen
Components of the extrapyramidal system provide subconscious control of skeletal muscle tone and coordinates learned movement patterns and other somatic motor activities.
They function in the control of voluntary movement and assist in the pattern and rhythm (especially for trunk and proximal limb muscles movement)

43. Brain Cerebrum - basal nuclei = control motor functions
( Parkinson’s disease)

44. Basal Nuclei
Info arrives at the caudate nucleus and the putamen from sensory, motor, and association areas of the cortex.
Processing and integration occurs w/i the nuclei and then info is sent from the globus pallidus to the motor cortex via the thalamus.
The basal nuclei alter motor commands issued by the cerebral cortex via this feedback loop.

45. Parkinson’s Disease
Each side of the midbrain contains a nucleus called the substantia nigra (SN).
Neurons in the substantia nigra inhibit the activity of basal nuclei by releasing dopamine.
Appearance of symptoms of Parkinson’s disease: tremor, slow movement, inability to move, rigid gait, reduced facial expression
Damage to SN neurons
Decrease in dopamine secretion
Gradual increase in muscle tone
Increased activity of basal nuclei

46. Brain Diencephalon = between cerebrum & brain stem
- consists of thalamus & hypothalamus, and epithalamus

47. Diencephalon

48. All 3 structures are gray matter and paired
Diencephalon
Forms the central core of the forebrain
All 3 structures are gray matter and paired

50. Diencephalon/Brainstem

51. Brain
Diencephalon
- thalamus = largest part of diencephalon, contains many nuclei
func: major relay station = directs incoming nerve impulses to correct cerebral cortex lobe

52. Thalamus 80% of the diencephalon
Sensory relay station where sensory signals can be edited, sorted, and routed.
Also has profound input on motor (via the basal nuclei and cerebellum) and cognitive function.
Not all functions have been elucidated.

53. Brain
Diencephalon
- hypothalamus = inferior to thalamus. Contains many nuclei
functions:
- regulate body temp. (thermostat of body)

54. Brain Diencephalon - hypothalamus functions: - hunger center
- satiety center
- sleep-wake cycles
- sexual development & functions
- controls viscera
Control of hunger and body wt

55. Hypothalamus Functions: Autonomic regulatory center
Influences HR, BP, resp. rate,
GI motility, pupillary diameter.
Emotional response
Involved in fear, loathing, pleasure
Drive center: sex, hunger
Regulation of body temperature
Regulation of food intake
Contains a satiety center
Regulation of water balance and thirst
Regulation of sleep/wake cycles
Hormonal control
Releases hormones that influence hormonal
secretion from the anterior pituitary gland.
Releases oxytocin and vasopressin
Can you hold your
breath until you die?

56. Epithalamus Above the thalamus
Contains the pineal gland which releases melatonin (involved in sleep/wake cycle and mood).
Contains a structure called the habenula – involved in food and water intake

57. Brain 2nd largest region of the brain.
Cerebellum:
Means little brain
Cerebellar cortex-gray matter with gyri and sulci
Lies inferior to the cerebrum and occupies the posterior cranial fossa.
2nd largest region of the brain.
10% of the brain by volume, but it contains 50% of its neurons
Damage- muscle tone decreases and fine motor movement becomes very clumsy.

58. Cerebellum Has 2 primary functions:
Adjusting the postural muscles of the body.
Coordinates rapid, automatic adjustments to maintain balance and equilibrium
2. Programming and fine-tuning movements controlled at the subconscious and conscious levels.
Refines learned movement patterns by regulating activity of both the pyramidal and extrapyramidal motor pathways of the cerebral cortex.
Compares motor commands with sensory info from muscles and joints and performs adjustments to make the movement smooth.

59. Brain
Cerebellum:
Compares information about the intended movement from the motor cortex with sensory information from the moving structures
Leads to smooth and coordinated movements
Alcohol acts to inhibit the function of the cerebellum (cerebellar comparator function impaired  fail the finger to nose test)

60. Cerebellum
May be permanently damaged by trauma or stroke, but the effects of alcohol generally are temporary.
Effects are impaired balance, impaired muscle tone, and impaired coordination of fine motor movement.
These alterations can produce ataxia a disturbance in balance.