Download SPPA 205

Outline
I.
Anatomy of the Nervous System
i.
Central Nervous System
•
•
•
•
•
•
•
•
Basic Organization
Cerebral Hemispheres
Basal Nuclei (Basal Ganglia)
Thalamus & Hypothalamus
Cerebellum
Limbic System
Brainstem
Spinal Cord
SPPA 2050 Speech Anatomy &
Physiology
1
Spinal cord
Dorsal
Ventral
Netter
SPPA 2050 Speech Anatomy &
Physiology
2
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
3
“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
4
“Segmental” Organization
Figure 39.22
SPPA 2050 Speech Anatomy &
Physiology
5
Reminder: The stretch reflex
is mediated within the spinal
cord
SPPA 2050 Speech Anatomy &
Physiology
6
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
7
Outline
I.
Anatomy of the Nervous System
i.
ii.
iii.
Central Nervous System
Peripheral Nervous System
Nourishment and Protection
•
•
•
Blood supply and return
Meninges
Ventricles and cerebrospinal fluid
SPPA 2050 Speech Anatomy &
Physiology
8
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
9
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
10
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
11
Arterial supply for CNS
Fig 7-29
SPPA 2050 Speech Anatomy &
Physiology
12
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
13
Figure 40.8
SPPA 2050 Speech Anatomy &
Physiology
14
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
15
Figure 40.10
SPPA 2050 Speech Anatomy &
Physiology
16
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
17
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
18
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
19
Outline
I.
Anatomy of the Nervous System
i.
ii.
iii.
Central Nervous System
Peripheral Nervous System
Nourishment and Protection
•
•
•
Blood supply and return
Meninges
Ventricles and cerebrospinal fluid
SPPA 2050 Speech Anatomy &
Physiology
20
Protecting the Brain
• Meninges
– Layered “wrapping” of the brain
• Ventricular system
– Internal cavities filled with cerebrospinal fluid
SPPA 2050 Speech Anatomy &
Physiology
21
Meninges
• Consists of three layers:
– Dura mater
– Arachnoid membrane
– Pia mater
SPPA 2050 Speech Anatomy &
Physiology
22
Meninges
• Mater = “mother”
• Pia = “delicate”
delicate mother
• Arachnoid = “spider”
spider mother
• Dura = “tough”
tough mother
SPPA 2050 Speech Anatomy &
Physiology
23
Meninges
Figure 39.25
SPPA 2050 Speech Anatomy &
Physiology
24
Dura mater
• Thick, tough, fibrous layer
• Headaches arise from sensory receptors
within the dura mater
SPPA 2050 Speech Anatomy &
Physiology
25
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
26
Pia mater
• Layer closest to the brain surface
• Actually follows the surface into sulci
SPPA 2050 Speech Anatomy &
Physiology
27
“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
28
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
29
Figure 39.20
SPPA 2050 Speech Anatomy &
Physiology
30
Outline
I.
Anatomy of the Nervous System
i.
ii.
iii.
Central Nervous System
Peripheral Nervous System
Nourishment and Protection
•
•
•
Blood supply and return
Meninges
Ventricles and cerebrospinal fluid
SPPA 2050 Speech Anatomy &
Physiology
31
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
32
Ventricles
Netter
SPPA 2050 Speech Anatomy &
Physiology
33
Figure 39.31
SPPA 2050 Speech Anatomy &
Physiology
34
Figure 39.30
SPPA 2050 Speech Anatomy &
Physiology
35
SPPA 2050 Speech Anatomy &
Physiology
36
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
37
Outline
I.
II.
Anatomy of the Nervous System
Afferent and Efferent Pathways
–
–
Motor Pathways
(Somato)Sensory Pathways
III. Centers and Circuits for the Neural
Control of Speech
SPPA 2050 Speech Anatomy &
Physiology
38
“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
39
Brainstem: ventral
Midbrain
Pons
pyramids
decussation
Medulla
Figure 39.19
SPPA 2050 Speech Anatomy &
Physiology
40
Medulla
pyramids
SPPA 2050 Speech Anatomy &
Physiology
41
Selected Structure
Side of Body
Cerebral cortex
Basal ganglia
Thalamus
Cerebellum
Brainstem*
Contralateral
Contralateral
Contralateral
Ipsilateral
Rostral-Contralateral
Caudal-Ipsilateral
Ipsilateral
Spinal cord
*depends on body part & site within brainstem
SPPA 2050 Speech Anatomy &
Physiology
42
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
43
Primary Motor Cortex
(Fig 7-38)
SPPA 2050 Speech Anatomy &
Physiology
44
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
45
Somatosensory Cortex
(Fig 7-38)
SPPA 2050 Speech Anatomy &
Physiology
46
• 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
47
A real case study
SPPA 2050 Speech Anatomy &
Physiology
48
Primary Somatosensory Pathways
(Fig 7-40)
SPPA 2050 Speech Anatomy &
Physiology
49
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
50
SPPA 2050 Speech Anatomy &
Physiology
51
Pyramidal Motor Pathway
(Fig 7-43)
SPPA 2050 Speech Anatomy &
Physiology
52
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
53
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
54
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
55
Contralateral vs. Bilateral Representation
of Cranial Nerve Function
Cranial N.
Trigeminal N.
Facial N.
Upper Face
Lower Face
Glossopharyngeal N.
Vagus N.
Accessory N.
Hypoglossal N.
UMN Innervation
Bilateral
Bilateral
Contralateral
Bilateral
Bilateral
Bilateral
Contralateral
SPPA 2050 Speech Anatomy &
Physiology
56
SPPA 2050 Speech Anatomy &
Physiology
57
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
58
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
59
Outline
I. Anatomy of the Nervous System
II. Afferent and Efferent Pathways
III. Centers and Circuits for the Neural
Control of Speech
SPPA 2050 Speech Anatomy &
Physiology
60
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
61
Some speech & language circuits
Figure 7-49
SPPA 2050 Speech Anatomy &
Physiology
62
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
63
Some speech & language circuits
Figure 7-49
SPPA 2050 Speech Anatomy &
Physiology
64
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
65
Some speech & language circuits
Figure 7-49
SPPA 2050 Speech Anatomy &
Physiology
66
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
67
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
68
Some speech & language circuits
Figure 7-49
SPPA 2050 Speech Anatomy &
Physiology
69
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
70
Some speech & language circuits
Figure 7-49
SPPA 2050 Speech Anatomy &
Physiology
71
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
72
Other important areas
• Thalamus
• Somatosensory cortex
• Primary & association areas of auditory
cortex
SPPA 2050 Speech Anatomy &
Physiology
73
Some speech & language circuits
Figure 7-49
SPPA 2050 Speech Anatomy &
Physiology
74
SPPA 2050 Speech Anatomy &
Physiology
75