1. SPPA 2050 Speech Anatomy & Physiology
Outline
Anatomy of the Nervous System
Central Nervous System
Basic Organization
Cerebral Hemispheres
Basal Nuclei (Basal Ganglia)
Thalamus & Hypothalamus
Cerebellum
Limbic System
Brainstem
Spinal Cord
SPPA 2050 Speech Anatomy & Physiology

2. SPPA 2050 Speech Anatomy & Physiology
Spinal cord
Dorsal
Ventral
Netter
SPPA 2050 Speech Anatomy & Physiology

3. SPPA 2050 Speech Anatomy & Physiology
Spinal cord
Gray matter
Butterfly-shaped (“H”-shaped) area within spinal cord white matter
Each “wing” is called a horn
Ventral horn – contains bodies of motor neurons
Dorsal horn – receives sensory information
Tracts from white matter terminate and often arise from this area as well as synapses from reflexes
White matter
Tracts that project up to the brain from the body
Tracts that project from the brain to the body
Communication between segmental levels of the spinal cord
SPPA 2050 Speech Anatomy & Physiology

4. “Segmental” Organization
Spinal cord is organized length-wise as a series of segments that are quite similar in structure
Each segment is associated with a pair of spinal nerves
There is a tendency for a segment to be associated with function at a level of the body
SPPA 2050 Speech Anatomy & Physiology

5. “Segmental” Organization
Figure 39.22
SPPA 2050 Speech Anatomy & Physiology

6. Reminder: The stretch reflex is mediated within the spinal cord
SPPA 2050 Speech Anatomy & Physiology

7. SPPA 2050 Speech Anatomy & Physiology
Outline
Anatomy of the Nervous System
Central Nervous System
Peripheral Nervous System
Cranial Nerves
Know all 12 cranial nerves by name
Know sensory and motor function associated with CN V, VII, IX, X, XI, XII
Spinal Nerves
Remember there are 31 spinal nerves
SPPA 2050 Speech Anatomy & Physiology

8. SPPA 2050 Speech Anatomy & Physiology
Outline
Anatomy of the Nervous System
Central Nervous System
Peripheral Nervous System
Nourishment and Protection
Blood supply and return
Meninges
Ventricles and cerebrospinal fluid
SPPA 2050 Speech Anatomy & Physiology

9. SPPA 2050 Speech Anatomy & Physiology
Nourishing the CNS
Blood is the means by which the brain is supplied oxygen and nutrients
Brain is 2 % of body mass, but uses about 20 % of blood in the body
SPPA 2050 Speech Anatomy & Physiology

10. SPPA 2050 Speech Anatomy & Physiology
Nourishing the CNS
Glycogen: energy source for the brain
brain can’t keep stores of glycogen
Without blood, the brain quickly becomes “malnourished” without oxygen and nutrients
Neural cell death occurs rapidly (within a few minutes)
SPPA 2050 Speech Anatomy & Physiology

11. SPPA 2050 Speech Anatomy & Physiology
Nourishing the CNS
Blood is supplied to the body from the heart via arteries
Blood is returned to the heart via veins
In CNS the term sinus refers to a collection of veins
SPPA 2050 Speech Anatomy & Physiology

12. Arterial supply for CNS
Fig 7-29
SPPA 2050 Speech Anatomy & Physiology

13. Important Arterial Branches
Internal Carotid Artery
Middle cerebral artery (MCA)
Anterior cerebral artery
Vertebral Artery
Combines to form basilar artery
Basilar artery has branches that supply brainstem and cerebellum
Basilar artery splits to become the posterior cerebral artery
SPPA 2050 Speech Anatomy & Physiology

14. SPPA 2050 Speech Anatomy & Physiology
Figure 40.8
SPPA 2050 Speech Anatomy & Physiology

15. Inferior View (Circle of Willis)
anterior
anterior cerebral a.
internal carotid a.
middle cerebral a.
posterior cerebral a.
superior
cerebellar a.
basilar a.
vertebral a.
Anterior inferior
cerebellar a.
posterior
SPPA 2050 Speech Anatomy & Physiology

16. SPPA 2050 Speech Anatomy & Physiology
Figure 40.10
SPPA 2050 Speech Anatomy & Physiology

17. Middle Cerebral Artery (MCA)
Supplies
most of brain’s lateral surface
Most of
frontal lobe
temporal lobe
basal ganglia
thalamus
insula
SPPA 2050 Speech Anatomy & Physiology

18. Anterior Cerebral Artery
Supplies front and medial surface of the brain.
Posterior Cerebral Artery
Supplies posterior temporal lobe and occipital lobe
SPPA 2050 Speech Anatomy & Physiology

19. SPPA 2050 Speech Anatomy & Physiology
Clinical note
stroke or cerebrovascular accident (CVA)
A blockage of blood vessels in the brain
May be due to
thrombosis (clot)
embolism (object floating through the bloodstream)
hemorrhage (bursting blood vessel)
can have devastating effects on communication
SPPA 2050 Speech Anatomy & Physiology

20. SPPA 2050 Speech Anatomy & Physiology
Outline
Anatomy of the Nervous System
Central Nervous System
Peripheral Nervous System
Nourishment and Protection
Blood supply and return
Meninges
Ventricles and cerebrospinal fluid
SPPA 2050 Speech Anatomy & Physiology

21. SPPA 2050 Speech Anatomy & Physiology
Protecting the Brain
Meninges
Layered “wrapping” of the brain
Ventricular system
Internal cavities filled with cerebrospinal fluid
SPPA 2050 Speech Anatomy & Physiology

22. SPPA 2050 Speech Anatomy & Physiology
Meninges
Consists of three layers:
Dura mater
Arachnoid membrane
Pia mater
SPPA 2050 Speech Anatomy & Physiology

23. SPPA 2050 Speech Anatomy & Physiology
Meninges
Mater = “mother”
Pia = “delicate”
delicate mother
Arachnoid = “spider”
spider mother
Dura = “tough”
tough mother
SPPA 2050 Speech Anatomy & Physiology

24. SPPA 2050 Speech Anatomy & Physiology
Meninges
Figure 39.25
SPPA 2050 Speech Anatomy & Physiology

25. SPPA 2050 Speech Anatomy & Physiology
Dura mater
Thick, tough, fibrous layer
Headaches arise from sensory receptors within the dura mater
SPPA 2050 Speech Anatomy & Physiology

26. SPPA 2050 Speech Anatomy & Physiology
Arachnoid membrane
Is a web-like structure between the dura and pia mater
There is space within the web, which is filled with cerebrospinal fluid
This arrangement sets up a fluid cushion to protect against injury
SPPA 2050 Speech Anatomy & Physiology

27. SPPA 2050 Speech Anatomy & Physiology
Pia mater
Layer closest to the brain surface
Actually follows the surface into sulci
SPPA 2050 Speech Anatomy & Physiology

28. “Spaces” between mater
Space between skull and dura mater
Extradural space
Space between dura and arachnoid mater
Subdural space
Space between arachnoid and pia mater
Subarachnoid space
SPPA 2050 Speech Anatomy & Physiology

29. SPPA 2050 Speech Anatomy & Physiology
Clinical note
Disease and disorder associated with the brain can actually be traced to the meninges
Meningitis (inflammation of the meninges)
can result in impaired neurologic function
Meningioma (tumor of the meninges)
can invade the brain and cause serious impairment in function
Hematoma (bruising) or hemorrhage (bleeding) can occur into spaces (extradural, subdural, subarachnoid)
SPPA 2050 Speech Anatomy & Physiology

30. SPPA 2050 Speech Anatomy & Physiology
Figure 39.20
SPPA 2050 Speech Anatomy & Physiology

31. SPPA 2050 Speech Anatomy & Physiology
Outline
Anatomy of the Nervous System
Central Nervous System
Peripheral Nervous System
Nourishment and Protection
Blood supply and return
Meninges
Ventricles and cerebrospinal fluid
SPPA 2050 Speech Anatomy & Physiology

32. SPPA 2050 Speech Anatomy & Physiology
Ventricles
4 interconnecting fluid filled spaces within the brain
Fluid is cerebrospinal fluid (CSF)
CSF
produced by the choroid plexus within the ventricles
considered to be principally protective
may be nutritive function
SPPA 2050 Speech Anatomy & Physiology

33. SPPA 2050 Speech Anatomy & Physiology
Ventricles
Netter
SPPA 2050 Speech Anatomy & Physiology

34. SPPA 2050 Speech Anatomy & Physiology
Figure 39.31
SPPA 2050 Speech Anatomy & Physiology

35. SPPA 2050 Speech Anatomy & Physiology
Figure 39.30
SPPA 2050 Speech Anatomy & Physiology

36. SPPA 2050 Speech Anatomy & Physiology

37. SPPA 2050 Speech Anatomy & Physiology
Clinical note
Excess CSF is called hydrocephalus (literally, water on the brain), which can occur for a number of reasons and impair normal nervous system function
SPPA 2050 Speech Anatomy & Physiology

38. SPPA 2050 Speech Anatomy & Physiology
Outline
Anatomy of the Nervous System
Afferent and Efferent Pathways
Motor Pathways
(Somato)Sensory Pathways
Centers and Circuits for the Neural Control of Speech
SPPA 2050 Speech Anatomy & Physiology

39. SPPA 2050 Speech Anatomy & Physiology
“Crossed” function
Central neural representation is often “crossed”
L cortex – sensation/motor to R side of body
R cortex – sensation/motor to L side of body
When fibers cross, they are said to decussate
Contralateral – opposite side
Ipsilateral – same side
SPPA 2050 Speech Anatomy & Physiology

40. SPPA 2050 Speech Anatomy & Physiology
Brainstem: ventral
Midbrain
Pons
pyramids
decussation
Medulla
Figure 39.19
SPPA 2050 Speech Anatomy & Physiology

41. SPPA 2050 Speech Anatomy & Physiology
Medulla
pyramids
SPPA 2050 Speech Anatomy & Physiology

42. SPPA 2050 Speech Anatomy & Physiology
Selected Structure Side of Body
Cerebral cortex Contralateral
Basal ganglia Contralateral
Thalamus Contralateral
Cerebellum Ipsilateral
Brainstem* Rostral-Contralateral
Caudal-Ipsilateral
Spinal cord Ipsilateral
*depends on body part & site within brainstem
SPPA 2050 Speech Anatomy & Physiology

43. Cortical Representation: Motor Function
Primary motor area is strip of cortex anterior to the central sulcus
Names for this area
precentral gyrus
Motor strip
Motor cortex
Primary motor cortex
Brodmann Area 4
SPPA 2050 Speech Anatomy & Physiology

44. SPPA 2050 Speech Anatomy & Physiology
Primary Motor Cortex
(Fig 7-38)
SPPA 2050 Speech Anatomy & Physiology

45. Cortical Representation: Somatosensory Function
Primary somatosensory area is a strip of cortex posterior to the central sulcus
Names for this area
post central gyrus
Sensory strip
Primary sensory cortex
Somatosensory cortex
Brodmann Area 1, 2, 3, 5
SPPA 2050 Speech Anatomy & Physiology

46. SPPA 2050 Speech Anatomy & Physiology
Somatosensory Cortex
(Fig 7-38)
SPPA 2050 Speech Anatomy & Physiology

47. SPPA 2050 Speech Anatomy & Physiology
Some body parts have more cortical space dedicated to them
e.g. Face, lips, tongue jaw
Indicates
Greater motor precision
Richer sensory information
SPPA 2050 Speech Anatomy & Physiology

48. SPPA 2050 Speech Anatomy & Physiology
A real case study
SPPA 2050 Speech Anatomy & Physiology

49. SPPA 2050 Speech Anatomy & Physiology
Primary Somatosensory Pathways
(Fig 7-40)
SPPA 2050 Speech Anatomy & Physiology

50. Neural Pathways of Motor Control
Pyramidal (Direct) motor system
Contains projection fibers from the cerebral cortex to the (lower) motor neurons
Includes primary motor cortex (60 %), premotor and sensory cortex (40%)
Associated with voluntary (willful) movement
Extrapyramidal (Indirect) motor system
Neural circuitry that does not directly synapse onto (lower) motor neurons
Includes basal ganglia and related structures
Indirectly modulates motor “instructions” sent to muscle
SPPA 2050 Speech Anatomy & Physiology

51. SPPA 2050 Speech Anatomy & Physiology

52. SPPA 2050 Speech Anatomy & Physiology
Pyramidal Motor Pathway
(Fig 7-43)
SPPA 2050 Speech Anatomy & Physiology

53. SPPA 2050 Speech Anatomy & Physiology
Projection Fibers
Corticospinal Tract
Fiber tract that connects cerebral cortex and ventral horn of spinal cord
Corticobulbar Tract
Fiber tract that connects cerebral cortex and cranial nerve nuclei in the brainstem
SPPA 2050 Speech Anatomy & Physiology

54. Upper vs. Lower Motor Neuron
Upper Motor Neuron
Cell body/dendrite typically in cerebral cortex
Axon in corticospinal or corticobulbar tract
Synapses onto lower motor neuron
Lower Motor Neuron
Cell body/dendrite in ventral horn of spinal cord or in a cranial nerve nuclei of brainstem
Axon in peripheral nerve
Synapses onto muscle (neuromuscular junction)
SPPA 2050 Speech Anatomy & Physiology

55. SPPA 2050 Speech Anatomy & Physiology
Clinical Note
Damage to Upper Motor Neuron
Spastic paralysis
Increased muscle tone
Exaggerated reflexes
Damage to Lower Motor Neuron
Flaccid paralysis
Absent or reduced reflexes
Decreased muscle tone
Atrophy of muscle
SPPA 2050 Speech Anatomy & Physiology

56. Contralateral vs. Bilateral Representation of Cranial Nerve Function
Cranial N. UMN Innervation
Trigeminal N. Bilateral
Facial N.
Upper Face Bilateral
Lower Face Contralateral
Glossopharyngeal N. Bilateral
Vagus N. Bilateral
Accessory N. Bilateral
Hypoglossal N. Contralateral
SPPA 2050 Speech Anatomy & Physiology

57. SPPA 2050 Speech Anatomy & Physiology

58. Sensorimotor Regulation
Sensory and motor function are inextricably linked
Movement generates afferent signals
Movement relies on knowledge of environment (via afferent signals)
SPPA 2050 Speech Anatomy & Physiology

59. Sensorimotor Regulation
Speech production stimulates a number of sensory modalities
Tactile information
Kinesthesia/proprioception
Audition
Short term disruptions to sensory systems do tend not to interfere with speech production
Long term disruption may be more damaging
e.g. hearing loss
SPPA 2050 Speech Anatomy & Physiology

60. SPPA 2050 Speech Anatomy & Physiology
Outline
Anatomy of the Nervous System
Afferent and Efferent Pathways
Centers and Circuits for the Neural Control of Speech
SPPA 2050 Speech Anatomy & Physiology

61. Localization of speech/language?
Distributed function
However, language is prominently represented in the dominant hemisphere (which in most is the left hemisphere)
SPPA 2050 Speech Anatomy & Physiology

62. Some speech & language circuits
Figure 7-49
SPPA 2050 Speech Anatomy & Physiology

63. SPPA 2050 Speech Anatomy & Physiology
Broca’s area
Location
anterior to the primary motor area (the face and mouth area) on or near the inferior frontal gyrus of the dominant hemisphere (usually left)
Presumed Function
Associated with planning speech production
Clinical
Damage: expressive or Broca’s aphasia*
Compromises expressive language
Preservation in receptive language
*aphasia = loss of language function
SPPA 2050 Speech Anatomy & Physiology

64. Some speech & language circuits
Figure 7-49
SPPA 2050 Speech Anatomy & Physiology

65. SPPA 2050 Speech Anatomy & Physiology
Wernicke’s area
Location
Planum temporale & posterior 2/3 of superior temporal gyrus of dominant hemisphere (usually left)
Presumed Function
Important for the understanding and formulation of language
Clinical
Damage: receptive or Wernicke’s aphasia
Limited receptive language
Fluent expressive language with little content/meaning
SPPA 2050 Speech Anatomy & Physiology

66. Some speech & language circuits
Figure 7-49
SPPA 2050 Speech Anatomy & Physiology

67. Supplementary motor area
Location
Medial surface of frontal lobe
Presumed Function
Involved in planning motor sequences including preparation of movement
“Internally” generated motor plans
implicated in planning of propositional speech
Strong linkages to basal ganglia
Clinical
Implicated in speech programming problems
Apraxia* of speech?
*Apraxia of speech: problem with programming sequences of the speech movements
SPPA 2050 Speech Anatomy & Physiology

68. SPPA 2050 Speech Anatomy & Physiology
Primary Motor Cortex
Clinical
Damage: can result in paralysis of speech musculature
Can results in spastic dysarthria*
*dysarthria – neurologically based problem with executing speech motor patterns
SPPA 2050 Speech Anatomy & Physiology

69. Some speech & language circuits
Figure 7-49
SPPA 2050 Speech Anatomy & Physiology

70. SPPA 2050 Speech Anatomy & Physiology
Basal Ganglia
Clinical
Damage: does not result in paralysis of speech musculature
Can results in hypokinetic or hyperkinetic dysarthria
Hypokinetic: lack of movement
Hyperkinetic: excess movement
SPPA 2050 Speech Anatomy & Physiology

71. Some speech & language circuits
Figure 7-49
SPPA 2050 Speech Anatomy & Physiology

72. SPPA 2050 Speech Anatomy & Physiology
Cerebellum
Clinical
Damage: does not result in paralysis of speech musculature
Can results in ataxic dysarthria
ataxia: poorly scaled and coordinated movement
SPPA 2050 Speech Anatomy & Physiology

73. SPPA 2050 Speech Anatomy & Physiology
Other important areas
Thalamus
Somatosensory cortex
Primary & association areas of auditory cortex
SPPA 2050 Speech Anatomy & Physiology

74. Some speech & language circuits
Figure 7-49
SPPA 2050 Speech Anatomy & Physiology

75. SPPA 2050 Speech Anatomy & Physiology