1. The Central Nervous System13
The Central Nervous System

2. Brain and Spinal Cord

3. I. The Brain A. Brain controls:
1. heart rate, respiratory rate, blood pressure
2. autonomic nervous system
3. endocrine system
4. innervation of head through the cranial nerves

4. B. Performs the most complex neural functions
► Intelligence
► Consciousness
► Memory
► Sensory-motor integration
► Emotion
► Behavior
► Socialization

5. II. Embryonic Development of the Brain
Prosencephalon—the forebrain ► telencephalon
► diencephalon
Mesencephalon—the midbrain
Rhombencephalon—the hindbrain ► metencephalon
► myelencephalon

6. Structures of the adult brain
(superior)
Telencephalon  the cerebral hemispheres
Diencephalon  thalamus, hypothalamus, epithalamus
Mesencephalon  midbrain
Metencephalon  pons and cerebellum
Myelencephalon  medulla oblongata
(inferior)

7. Primary brain vesicles Week 4 Secondary brain vesicles Week 5
Neural tube
Primary brain vesicles Week 4
Secondary brain vesicles Week 5
Adult brain structures
Adult neural canal regions
Cerebrum: cerebral hemispheres (cortex, white matter, basal nuclei)
Lateral ventricles
Telencephalon
Anterior (rostral)
Prosencephalon (forebrain)
Diencephalon (thalamus, hypothalamus, epithalamus), retina
Third ventricle
Diencephalon
Mesencephalon (midbrain)
Mesencephalon
Brain stem: midbrain
Cerebral aqueduct
Rhombencephalon (hindbrain)
Metencephalon
Brain stem: pons
Cerebellum
Fourth ventricle
Myelencephalon
Brain stem: medulla oblongata
Posterior (caudal)
Spinal cord
Central canal 7

8. 8 Anterior (rostral) Posterior (caudal) Metencephalon Mesencephalon
Midbrain
Diencephalon
Flexures
Cervical
Telencephalon
Myelencephalon
Spinal cord
Week 5: Two major flexures form.
Cerebral hemisphere
Outline of diencephalon
Midbrain
Cerebral hemisphere
Cerebellum
Pons
Cerebellum
Medulla oblongata
Pons
Medulla oblongata
Spinal cord
Spinal cord
Week 13: Cerebral hemispheres grow posterolaterally, enclosing the diencephalon and the rostral brain stem.
Week 26: Surface of the cerebrum begins to fold.
Cerebrum
Diencephalon
Cerebellum
Brain stem
Midbrain
Pons
Medulla oblongata
Birth: Brain shows adult pattern of structures and convolutions. 8

9. III. Basic Parts and Organization of the Brain
A. Classified into four regions
1. brain stem = midbrain, pons, and medulla
2. cerebellum
3. diencephalon
4. cerebral hemispheres (cerebrum)  cerbral cortex

10. III. Ventricles of the Brain
A. The Ventricles - Expansions of the brain’s central cavity
► Filled with cerebrospinal fluid
► Lined with ependymal cells
► Continuous with each other
► Continuous with the central canal of the spinal cord

11. B. Lateral ventricles - located in cerebral hemispheres
► horseshoe-shaped from bending of the cerebral hemispheres
B. Third ventricle - lies in diencephalon
► connected with lateral ventricles by interventricular foramen
D. Cerebral aqueduct - connects 3rd and 4th ventricles
E. Fourth ventricle - lies in hindbrain
► connects to the central canal of the spinal cord

12. Interventricular foramen
Lateral ventricle
Interventricular foramen
Third ventricle
Median aperture
Cerebral aqueduct
Fourth ventricle
Lateral aperture
Central canal
Anterior view
Left lateral view 12

13. IV. The Brain Stem A. General Features
1. Passageway for all fiber tracts running between the cerebrum and spinal cord
2. Heavily involved with the innervation of the face and head
10 of the 12 pairs of cranial nerves attach to it
3. Produces automatic behaviors necessary for survival
4. Integrates auditory and visual reflexes

14. Midbrain
Pons
Medulla oblongata 14

15. 15

16. B. The Medulla Oblongata
1. Areas
a. pyramids of the medulla - lie on its ventral surface
b. decussation of the pyramids - crossing over of motor tracts ***
c. inferior cerebellar peduncles - tracts to medulla and cerebellum
d. olive (olive of the medulla) - contains inferior olivary nucleus
2. Functions
a. cardiac center
b. vasomotor center
c. medullary respiratory center
d. centers for hiccupping, sneezing, swallowing, and coughing

17. C. The Pons
1. the “bridge” between the midbrain and medulla
2. motor tracts – coming from the cerebral cortex
3. connects the cortex with the cerebellum
a. through the middle cerebellar peduncles

18. D. The Midbrain 1. lies between the diencephalon and the pons
2. location of the cerebral aqueduct
3. cerebral peduncles
a. with the corticospinal tracts
4. superior cerebellar peduncles
a. connect midbrain to cerebellum
5. periaqueductal grey matter
a. fight-or-flight actions
b. mediates response to visceral (non-skin) pain

19. D. The Midbrain
6. Superior colliculi – nuclei that respond to visual reflexes
7. Inferior colliculi – nuclei that respond to auditory reflexes
8. Substantia nigra – involved in motor function (Parkinson’s disease)

20. Illustration of parasagittal section
Cerebellar peduncles
Superior
Middle
Inferior
Medulla oblongata
Illustration of parasagittal section 20

21. V. The Cerebellum A. General Features
1. located dorsal to the pons and medulla
2. smoothing and coordinating body movements
3. helps maintain equilibrium
4. contains “folds” called folia
5. consists of two cerebellar hemispheres
a. anterior, posterior and flocculonodular lobes in each
6. three regions – cortex (grey), arbor vitae (white) and cerebellar nuclei

22. Illustration of parasagittal section
Anterior lobe
Cerebellar cortex
Arbor vitae
Pons
Posterior lobe
Medulla oblongata
Flocculonodular lobe
Illustration of parasagittal section 22

23. Illustration of parasagittal section23

24. Arbor vitae (Arbor = Tree)
Anterior lobe
Arbor vitae (Arbor = Tree)
Cerebellar cortex
Folia
Pons
Fourth ventricle
Posterior lobe
Medulla oblongata
Midsagittal section 24

25. B. Functions
1. To coordinate body movements
a. information on equilibrium
b. information on current body movements
c. information coming from cerebral cortex (voluntary)
2. Superior, Middle and Inferior Cerebellar Peduncles
a. fibers (axons) to/from brainstem that are ipsilateral

26. VI. The Diencephalon A. General Features
1. forms the central core of the forebrain
2. surrounded by the cerebral hemispheres
3. composed of three paired structures
a. thalamus
b. hypothalamus
c. epithalamus
4. primarily composed of gray matter

27. 27 Cerebral hemisphere Thalamus (encloses third ventricle)
Posterior commissure
Epithalamus
Pineal gland
Hypothalamus
Pituitary gland
Pons
Cerebellum
Medulla oblongata 27

28. 28 Thalamus (encloses third ventricle) Posterior commissure
Epithalamus
Pineal gland
Hypothalamus
Cerebellum
Pons
Medulla oblongata 28

29. B. Thalamus
1. “football” shaped structure the size of the thumb phalanx
2. makes up 80% of the diencephalon
3. contains many important nuclei
4. relay station for all information up/down to the cortex!!
5. nuclei dampen or amplify relay messages

30. Lateral dorsal nucleus
Medial dorsal nucleus
Lateral posterior nucleus
Internal medullary lamina
Pulvinar
Anterior nuclei
Medial geniculate body
Reticular nucleus
Lateral geniculate body
Ventral postero- lateral
Ventral anterior
Ventral lateral
The main thalamic nuclei. (The reticular nuclei that “cap” the thalamus laterally are depicted as curving translucent structures.) 30

31. 1. main visceral control center of the body
B. Hypothalamus
1. main visceral control center of the body
2. pituitary gland projects inferiorly
3. functions include the following:
► Control of the ANS
► Control of emotional responses
► Regulation of body temperature
► Regulation of hunger and thirst sensations
► Control of behavior
► Regulation of sleep-wake cycles
► Control of the endocrine system
► Formation of memory

32. Anterior commissure
Paraventricular nucleus
Fornix
Dorsomedial nucleus
Preoptic nucleus
Posterior hypothalamic nucleus
Anterior hypothalamic nucleus
Lateral hypothalamic area
Supraoptic nucleus
Suprachiasmatic nucleus
Ventromedial nucleus
Optic chiasma
Arcuate nucleus
Mammillary body
Infundibulum (stalk of the pituitary gland)
Pituitary gland
The main hypothalamic nuclei 32

33. C. Pineal Gland
1. Secretes the hormone melatonin
2. Under influence of the hypothalamus
3. Aids in control of circadian rhythm

34. VII. The Cerebral Hemispheres
A. General Features
1. account for 83% of brain mass
2. composed of gray matter
3. folds in cortex - triples its size
4. fissures - grooves that separate major regions of the brain
a. transverse fissure - separates cerebrum and cerebellum
b. longitudinal fissure - separates cerebral hemispheres
5. sulci - valleys on the surface of the cerebral hemispheres
6. gyri - ridges (“hills”)

35. 7. lobes – frontal, parietal, occipital, temporal
8. central sulcus separates frontal and parietal lobes
a. precentral gyrus – primary motor cortex
b. postcentral gyrus – primary somatosensory cortex
9. parieto-occipital sulcus - separates occipital from parietal lobe
10. lateral sulcus - separates temporal from parietal and frontal lobes
11. Brodmann areas - 47 structurally & functionally distinct areas!!!!!

36. Parieto- occipital sulcus
Central sulcus
Precentral gyrus
Postcentral gyrus
Frontal
lobe
Parietal lobe
Parieto- occipital sulcus
Lateral sulcus
Occipital lobe
Fissure (a deep sulcus)
Temporal lobe
Gyrus
Cortex (gray matter)
Sulcus
White matter
Lobes and sulci of the cerebrum 36

37. Fissure (a deep sulcus)
Gyrus
Cortex (gray matter)
Sulcus
White matter
Lobes and sulci of the cerebrum 37

38. B. Primary Functions
1. home of our conscious mind
2. be aware of ourselves and our sensations
3. initiate and control voluntary movements
4. communicate, remember, and understand

39. VIII. Functional Regions of the Cortex !!!!
A. Three general kinds of functional areas
1. Sensory areas – area for each of the major senses
2. Association areas – process sensory and motor information
3. Motor areas – plans and initiates motor functions

40. WOW!! 40 Motor areas Central sulcus
Sensory areas and related association areas
Primary motor cortex
Primary somatosensory cortex
Premotor cortex
Somatic sensation
Frontal eye field
Somatosensory association cortex
Broca’s area (outlined by dashes)
Gustatory cortex (in insula)
Taste
Anterior association area (Prefrontal cortex)
Wernicke’s area (within the posterior association area outlined by dashes)
Working memory for spatial tasks
Executive area for task management
Working memory for object-recall tasks
Primary visual cortex
Solving complex, multitask problems
Visual association area
Vision
Auditory association area
Hearing
Primary auditory cortex
Lateral view, left cerebral hemisphere
Primary motor cortex
Motor association cortex
Primary sensory cortex
Sensory association cortex
Multimodal association cortex 40

41. WOW!! 41 Premotor cortex Primary motor cortex Central sulcus
Corpus callosum
Primary somatosensory cortex
Frontal eye field
Parietal lobe
Somatosensory association cortex
Prefrontal cortex
Parieto-occipital sulcus
Limbic association area
Cingulate gyrus
Occipital lobe
Processes emotions related to personal and social interactions
Visual association area
Orbitofrontal cortex
Olfactory bulb
Primary visual cortex
Olfactory tract
Calcarine sulcus
Fornix
Temporal lobe
Primary olfactory cortex
Uncus
Parahippocampal gyrus
Parasagittal view, right hemisphere
Primary motor cortex
Motor association cortex
Primary sensory cortex
Sensory association cortex
Multimodal association cortex 41

42. B. Dr. Wilder Penfield – experiments on patients who are awake!
1. Precentral gyrus – primary motor cortex
2. Postcentral gyrus – primary somatosensory cortex
3. Homonculus – making of body functions onto these gyri!!

43. 43 Posterior Motor Sensory Anterior Motor map in precentral gyrus
Sensory map in postcentral gyrus
Head
Shoulder
Trunk
Neck
Hip
Arm
Forearm
Elbow
Arm
Trunk
Knee
Leg
Hand
Wrist
Hip
Elbow
Hand
Fingers
Fingers
Knee
Thumb
Thumb
Foot
Eye
Neck
Brow
Nose
Eye
Face
Toes
Genitals
Lips
Face
Lips
Teeth
Gums
Jaw
Jaw
Tongue
Pharynx
Tongue
Primary motor cortex (precentral gyrus)
Primary somato- sensory cortex (postcentral gyrus)
Swallowing 43

44. C. Sensory areas of the cortex
1. primary visual cortex – occipital lobe
a. largest of all sensory areas
b. receives visual information that originates on the retina
c. first of a series of areas processing visual input
2. visual association area
a. continues the processing of visual information
b. analyzes color, form, and movement
3. primary auditory cortex
a. conscious awareness of sound
b. information comes from the cochlea of the inner ear

45. 4. Wernicke’s area - recognizing and understanding speech
5. vestibular cortex – conscious awareness of sense of balance
6. gustatory cortex - conscious awareness of taste stimuli
7. olfactory cortex - awareness of smells (oldest sense!)
a. connects the brain to the limbic system (emotions)
b. explains why smells trigger emotions

46. Sensory areas of cortex
Central sulcus
Sensory areas and related association areas
Primary somatosensory cortex
Somatic sensation
Somatosensory association cortex
Gustatory cortex (in insula)
Taste
Wernicke’s area
Primary visual cortex
Visual association area
Vision
Auditory association area
Hearing
Primary auditory cortex
Lateral view, left cerebral hemisphere
Primary motor cortex
Motor association cortex
Primary sensory cortex
Sensory association cortex
Multimodal association cortex 46

47. D. Motor areas of the cortex
1. Premotor cortex - Located anterior to the precentral gyrus
a. Controls more complex movements
b. Controls voluntary actions dependent on sensory feedback
c. Involved in planning movements
2. Frontal eye field - Lies anterior to the premotor cortex
a. Controls voluntary movement of the eyes
3. Broca’s area - Manages speech production

48. Motor areas of cortex 48 Motor areas Central sulcus
Primary motor cortex
Premotor cortex
Frontal eye field
Broca’s area
Anterior association area (Prefrontal cortex)
Working memory for spatial tasks
Executive area for task management
Working memory for object-recall tasks
Solving complex, multitask problems
Lateral view, left cerebral hemisphere
Primary motor cortex
Motor association cortex
Primary sensory cortex
Sensory association cortex
Multimodal association cortex 48

49. E. Multimodal association areas
1. make associations between kinds of sensory information
2. posterior ass. area - integrates sensory input into perception
3. anterior ass. area - integrates information with past experience
4. limbic ass. area - involved with memory and emotions
a. integrates sensory and motor behaviors
b. aids in the formation of memory
c. processes emotions

50. F. Lateralization of cortical function
1. The two hemispheres control opposite sides of the body
2. Contralateral  opposite side
3. Hemispheres are specialized for different cognitive functions
4. Left cerebral hemisphere—control over:
a. language abilities, math, and logic
5. Right cerebral hemisphere—involved with:
a. visual-spatial skills
b. reading facial expressions
c. Intuition, emotion, artistic and musical skills

51. IX. Cerebral White Matter
A. Different areas of the cerebral cortex:
1. Communicate with each other
2. Communicate with the brain stem and spinal cord
3. Consists of tracts carrying information from point A to point B
B. Commisures - communication between cerebral hemispheres
1. corpus callosum – connects left and right hemispheres
a. “split brain” patients are special
C. Association fibers - connect parts of the same hemisphere
D. Projection fibers – cortex to/from lower brain regions

52. Corpus callosum 52 Parasagittal view, right hemisphere
Primary motor cortex
Motor association cortex
Primary sensory cortex
Sensory association cortex
Multimodal association cortex 52

53. White fiber tracts of the cerebral hemispheres
Association fibers (within hemisphere)
Superior
Commissural fibers (between hemispheres)
Corpus callosum
Projection fibers (cerebral cortex to or from lower area)
Decussation (cross-over) of motor tracts)
Frontal section 53

54. White fiber tracts of the cerebral hemispheres
Association fibers
Commissural fibers
Corpus callosum
Projection fibers 54

55. X. Deep Gray Matter of the Cerebrum
A. Basal nuclei (basal ganglia) - involved in motor control
1. group of nuclei deep within the cerebral white matter
a. caudate nucleus—arches over thalamus
b. putamen
c. globus pallidus
2. cooperate with the cerebral cortex in controlling movement
3. start, stop, and regulate intensity of voluntary movements
B. Basal forebrain nuclei - associated with memory
C. Amygdaloid body - considered part of the of the limbic system

56. Basal nuclei (ganglia)
Caudate nucleus
Thalamus
Putamen
Substantia nigra of midbrain 56

57. X. Other Brain Systems A. Limbic system
1. the “emotional” and “memory” part of the brain
2. located in the temporal lobe
a. cingulate gyrus - allows us to shift between thoughts
b. hippocampus – formation of memories
c. amygdala – retrieval of memories
d. Alzheimer’s disease – location of “tangles” and “plaques”

58. Limbic system Corpus callosum Fornix
Cerebral structures of the limbic system
Cingulate gyrus
Amygdala
Hippocampus
Olfactory bulb 58

59. B. Reticular formation
1. arousal of the brain as a whole
2. maintains consciousness and alertness
3. functions in sleep and arousal from sleep
4. malfunctions in people with narcolepsy

60. Radiations to cerebral cortex
Reticular formation nuclei in brain stem 60

61. 61

62. 62

63. XI. The Meninges A. Dura mater (“tough mother”)
1. Outer layer - cover and protect the brain and spinal cord
2. Enclose and protect the vessels that supply the CNS
B. Arachnoid layer (“spider-like”)
1. Middle layer – location beneath which is cerebral spinal fluid (CSF)
C. Pia mater (‘light mother”)
1. Clings tightly to the surface of the brain and spinal cord

64. The Meninges Skin of scalp Periosteum Bone of skull Dura mater
Arachnoid mater
Pia mater 64

65. The Meninges 65

66. XII. Cerebral Spinal Fluid
A. Formed in choroid plexuses of all four brain ventricles
1. composed of ependymal cells and capillaries
2. derived from the liquid portion of the blood
ml produced per day
4. only 100–160 ml present at any one time

67. B. The Blood-Brain Barrier
1. prevents most blood borne toxins from entering the brain
2. nutrients such as oxygen pass through
3. allows passage of alcohol, nicotine, and anesthetics
4. does not allow some drugs to enter brain and spinal cord

68. 68 Superior sagittal sinus Choroid plexus Subarachnoid space
Arachnoid mater
Meningeal dura mater
Periosteal dura mater 1
Right lateral ventricle (deep to cut)
Interventricular foramen
Third ventricle 3
Choroid plexus of fourth ventricle
Cerebral aqueduct
Lateral aperture
Fourth ventricle
Median aperture 2
Central canal of spinal cord
CSF circulation 68

69. XIII. The Spinal Cord A. Functions 1. spinal nerves attach to it
2. provides two-way conduction pathway up and down
3. major center for reflexes
B. Location
1. runs through the vertebral canal
2. from the foramen magnum to vertebra L1 or L2

70. C. Gross Anatomy
1. conus medullaris - the inferior end of the spinal cord
2. filum terminale - filament of connective tissue to the coccyx
3. cervical and lumbar enlargements – upper and lower limbs
4. cauda equina (“horse tail”) - collection of spinal nerve roots
5. central canal – hole in center for passage of CSF
D. Spinal Cord “Segments”
1. indicate region of spinal cord from which spinal nerves emerge
2. designated by the spinal nerve that issues from it
3. NOTE: 7 cervical vertebrae but 8 cervical spinal nerves

71. Spinal Cord 71 Cervical spinal nerves Cervical enlargement
Dura and arachnoid mater
Spinal Cord
Thoracic spinal nerves
Lumbar enlargement
Conus medullaris
Lumbar spinal nerves
Cauda equina
Filum terminale
Sacral spinal nerves
The spinal cord and its nerve roots, with the bony vertebral arches removed. The dura mater and arachnoid mater are cut open and reflected laterally. 71

72. Spinal Segments 72 Dorsal (posterior) Ventral (anterior)
Spinal cord segment C1
Spinal nerve C1
Spinal cord segment T1
Spinal nerve C8
Spinal nerve T1
Spinous process T1
Spinal cord segment T5
Spinal nerve T5
Spinal Segments
Spinal cord segment L1
Spinal nerve L1
Spinal nerve S1 72

73. Epidural space (contains fat) Arachnoid mater Spinal meninges
Pia mater
Epidural space (contains fat)
Arachnoid mater
Spinal meninges
Dura mater
Subdural space
Subarachnoid space (contains CSF)
Dorsal root ganglion
Body of vertebra
Cross section of spinal cord and vertebra, cervical region 73

74. XIV. The Spinal Cord Areas
A. Grey matter – nerve cell bodies of motor and internuerons
1. two deep grooves run the length of the cord
a. posterior median sulcus
b. anterior median fissure
2. grey commisure – cross bar “H” in the middle
3. anterior (ventral) horns
4. posterior (dorsal) horns
5. lateral (intermediate) horns (T, L, S only)
See drawing on the board.

75. B. Gray matter is divided according to somatic and visceral regions
► SS - somatic sensory
► VS - visceral sensory
► VM - visceral motor
► SM - somatic motor
Also note:
dorsal area = sensory
ventral area = motor

76. Spinal nerve Ventral root (motor)
Dorsal root (sensory)
Dorsal horn (interneurons)
Dorsal root ganglion
Somatic sensory neuron
Visceral sensory neuron
Visceral motor neuron
Somatic motor neuron
Spinal nerve
Ventral horn (motor neurons)
Ventral root (motor)
Interneurons receiving input from somatic sensory neurons
Interneurons receiving input from visceral sensory neurons
Visceral motor (autonomic) neurons
Somatic motor neurons 76

77. C. White matter – myelinated axons of motor/sensory fibers
1. funiculus – anterior, posterior and lateral (only in T, L, S)
2. have tracts - carry information up and down the spinal cord
a. ascending tracts = sensory info UP to the brain
b. descending tracts = motor info DOWN from the brain

79. Ascending tracts
Descending tracts
Ventral white commissure
Dorsal white column
Reticulospinal tracts
Fasciculus gracilis
Medial
Fasciculus cuneatus
Lateral
Spinocerebellar tracts
Corticospinal tracts
(pyramidal tracts)
Dorsal
Lateral
Ventral
Ventral
Spinothalamic tracts
Lateral
Rubrospinal tract
Ventral
Vestibulospinal tract
Tectospinal tract 79

80. D. Ascending Tracts
TRACT FUNCTION
1. anterior (ventral) spinothalamic - touch and pressure to thalamus
2. lateral spinothalamic tract - pain & temperature to thalamus
3. fasciculus gracilis & cuneatus - touch, 2-pt. discrimination conscious proprioception, stereognosis, weight discrimination, vibration
4. posterior spinocerebellar - subconscious proprioception
5. anterior spinocerebellar - subconscious proprioception

81. Ascending tracts Ascending tracts Descending tracts
Dorsal white column
Fasciculus gracilis
Fasciculus cuneatus
Spinocerebellar tracts
Dorsal
Ventral
Spinothalamic tracts
Lateral
Ventral 81

82. Ascending tracts 82 Primary somatosensory cortex
Axons of third-order neurons
Thalamus
Cerebrum
Ascending tracts
Midbrain
Cerebellum
Pons
Dorsal spinocerebellar tract (axons of second-order neurons)
Medial lemniscus tract (axons of second-order neurons)
Lateral Spinothalamic tract (axons of second-order neurons)
Nucleus gracilis
Nucleus cuneatus
Medulla oblongata
Fasciculus cuneatus (axon of first-order sensory neuron)
Pain receptors
Joint stretch receptor (proprioceptor)
Axon of first-order neuron
Cervical spinal cord
Axons of first-order neurons
Fasciculus gracilis (axon of first-order sensory neuron)
Muscle spindle (proprioceptor)
Temperature receptors
Lumber spinal cord
Touch receptor
Spinocerebellar pathway
Dorsal column-medial lemniscal pathway
Spinothalamic pathway 82

83. E. Descending Tracts TRACTS FUNCTIONS
1. lateral & anterior corticospinal motor output from cortex motor to cells of ant. horn
2. rubrospinal motor from midbrain to anterior horn for precise movement
3. tectospinal motor from midbrain to anterior horn; movements in response to audiovisual/cutaneous stimuli
4. vestibulospinal motor from medulla to anterior horn; coordination/balance
5. lateral reticulospinal motor from medulla to anterior horn; inhibit extensor reflexes
6. medial reticulospinal motor from pons to anterior horn; facilitate extensor reflexes

84. Descending tracts Ascending tracts Descending tracts
Reticulospinal tracts
Medial
Lateral
Corticospinal tracts
(pyramidal tracts)
Lateral
Ventral
Rubrospinal tract
Vestibulospinal tract
Tectospinal tract 84

85. Descending tracts 85 Pyramidal cells (upper motor neurons)
Primary motor cortex
Internal capsule
Cerebrum
Descending tracts
Red nucleus
Midbrain
Cerebral peduncle
Cerebellum
Pons
Rubrospinal tract
Ventral corticospinal tract
Medulla oblongata
Pyramids
Decussation of pyramids
Lateral corticospinal tract
Cervical spinal cord
Skeletal muscle
Lumbar spinal cord
Somatic motor neurons (lower motor neurons)
Pyramidal (lateral and ventral corticospinal) pathways
Rubrospinal tract 85

86. Spinal Tap (Lumbar Puncture)
Ligamentum flavum
Lumbar puncture needle entering subarachnoid space L4
Supra- spinous ligament L5
Filum terminale S1
Inter- vertebral disc
Cauda equina in subarachnoid space
Arachnoid mater
Dura mater 86

87. XV. Disorders of the Central Nervous System
A. Spinal cord damage
1. paralysis - loss of motor function
2. parasthesia - loss of sensation
3. paraplegia - injury to the spinal cord is between T1 and L2
a. paralysis of the lower limbs
4. quadriplegia - injury to the spinal cord in the cervical region
a. paralysis of all four limbs

88. B. Brain dysfunction
1. cerebrovascular accident (stroke)
a. Blockage or interruption of blood flow to a brain region
2. Alzheimer’s disease
a. Progressive degenerative disease leading to dementias
C. Congenital malformations
1. hydrocephalus – “water on the brain” – CSF buildup
2. neural tube defects
a. anencephaly - cerebrum and cerebellum are absent
b. spina bifida - absence of vertebral lamina
3. cerebral palsy - voluntary muscles are poorly controlled
a. results from damage to the motor cortex