Download Temporal Aspects of Visual Extinction

Neurology 1
CNS Gross Anatomy
Donna Quezada, DC, DICCP, DIBCN
With some slides by Chris Rorden
[email protected]
Roles of the CNS
• Functions of neurons in the CNS (brain and spinal
cord) include:
– Sensor: Receives environmental and body stimuli
– Integrator: Combines information received
– Effector: Initiates body movements
– Regulator: Maintains homeostatic state for body
function
2
Nervous System
• The CNS is protected and isolated.
– Bone offers protection from injury
• Skull covers brain
• Vertebral Column covers spinal cord
– The is encased in soft-tissue membranes
– The brain’s blood vessels stop many subastances
from entering the brain (blood-brain barrier)
• Protects from contamination/infection
– The brain floats in cerebral spinal fluid
• Offers protection from impact
3
The Meninges
• Dura Mater: Tough outer covering
• Arachnoid Mater: Middle layer
• Pia Mater: Inner closely formed
layer
4
Brain Membranes: Meninges
• 3 layers
– Drua Mater (Tough Mother) aka: pachymeninx
• Tough outer layer, connects brain to bone
– Arachnoid Mater (Spidery Mother)
• Spidery middle layer, connects Dura to Pia
• Allows room for the cerebral spinal fluid
• Allows movement of the CNS within its boney housing
– Pia Mater (Small Mother)
• Thinner, glossy layer next to the brain
Dura – Functions
• Houses blood vessels and sinuses
• Main blood supply: middle meningeal artery
• Forms septa to encapsulate the brain
– Falx Cerebri
• Syuperior and inferior sagittal sinuses
– Tentorium Cerebelli
• Straight sinus (at junction of F. Cerebri and Tentorium)
• Transverse sinus
• Sigmoidsinus
– Diaphragma Sellae (covers the sella turcica)
– Falx Cerebelli
Arachnoid
• Delicate, transparent
• Attached to the dura
• Separate from the pia by the subarachnoid
space
– Contains trabeculae: crossing fibrous bands
– Cisterns: enlarged subarachnoid spaces
• Arachnoid villi
– Project into superior sagittal and other sinuses
– Permit CSF flow into the venous system
Pia
• Highly vascular
• Loose connective tissue
• Invests the small blood vessels to the brain and
spinal cord
• Contributes to the
– roof of the 3rd ventricle
– Choroid plexuses of the 3rd and 4th ventricles
• With arachnoid = leptomeninges (slender)
Cerebrospinal Fluid (CSF)
• Located between the
meninges and in the
ventricular cavities of the
brain
• Produced in the
ventricular cavities by the
choroid plexus
• Functions
– mechanical buffer
– fluid for metabolic functions
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"Copyright © 2005 by Thompson Delmar Learning, a division of Thomson Learning, Inc. ALL RIGHTS RESERVED"
CSF
• CSF is in ventricles, subarchnoid
space, interventricular foramens, and
around the spine.
• Circulates from ventricles around brain
and spinal column
• Is finally absorbed by venous system
• Replenishes at ventricles every 7 hours
10
Ventricles
• Lateral Ventricles
• Connected by
interventricular foramen
• Collateral trigone area
• Posterior and inferior horns
• Connects to Third Ventricle
through Monro’s foramen
11
Ventricles
• Birds Eye View
– Usually symmetrical in healthy people
12
Other ventricles…
• Third Ventricle
• Ventral to the corpora
quadrigemina
• Surrounded by central gray
area
• Connects to fourth ventricle
through Cerebral Aqueduct
• Fourth ventricle
– Near Pons / Medulla
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Ventricles
14
Ventricles in clinical setting
• Hydrocephalus
– E.G. cyst
15
Major Structures of the Brain
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Brain Superior View
Brain Inferior View
Brain Lateral View
Midsagittal Brain
Cerebral Cortex
• Convuluted to increase
surface
• Infintile reflexes and
reactions come and go
as this develops
• 14-16 billion neurons
reside in the gray matter
•
•
•
•
Gyri (bumps)
Sulci (grooves)
Fissures (deep sulci)
More neurons = more
gyri
• Lobes named for
covering bones
Function of Cortical Areas
• Precentral Gyrus: motor
control
• Postcentral Gyrus:
Somatosensory cortex
• Sensory humunculus is
more region specific than
the motor (fuzzy)
• Occipital lobe: vision,
motor and sensory
association
• Temporal: Hippocampal
and paracampal areas
– Speech
– Auditory Association
– Memory
• Speech: two parts
– Motor: Inferior frontal lobe:
Brocca’s
– Expressive: Wernicke’s
Aphasia (BA 44) temporal
lobe
Association and Commisseral Fibers
• Connect different areas
of the cortex
• White matter primarily
• Afferent and efferent
fibers form the corona
radiata
– Connecting fibers between
cortex and other central
structures
• Brain stem
• Spinal cord
• Fibers converge and
form:
– Internal Capsule
• Between thalamus, caudate
nuculeus, and lentiform
nuclei
• Commissures (connect)
– Corpus callosum
– Anterior commissure
– Hippocampal commissure
White matter fibers from the cortex
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Medullary Centers
• Interhemispheric (between) Connections
• Intrahemispheric (within) Connections
• Three types of fibers
– Projection: Project through internal capsule
– Association: Within a hemisphere
i.e. Arcuate fasciculus
– Commissural: Between hemispheres i.e. Corpus
callosum
25
Major Fissure of the Brain
• Longitudinal Fissure
– Separates Two Hemispheres of the Brain
– Aka ‘Interhemispheric Fissure’
• Falx Cerebri resides here
– Superior sagittal sinus
– Inferior sagittal sinus
26
Major Folds of the Brain
• The folds of your brain are like a fingerprint – there are
a few general patterns, with individual variability.
• Two main folds
– Central Sulcus
Fissure of Rolando
Rolandic sulcus
– Lateral sulcus
Sylvian fissure
 The central sulcus separates
the frontal and parietal lobes.
 The lateral sulcus separates
the temporal lobe from frontal,
parietal, insula
27
The major cortical lobes
Insular Lobe – Tucked
away, but often injured
in patients seen by
speech pathologists
28
Major Medial Sulci
Central Sulcus
Parieto-occipital Sulcus
Calcarine Sulcus
Preoccipital Notch
29
Lobes et al of the Brain
30
Landmarks of the frontal lobe
•
•
•
•
•
•
Frontal Pole
Precentral Gyrus
Precentral Sulcus
Premotor Cortex
Speech, Fine Motor
Prefrontal Cortex
31
Frontal Lobe Functions
• Motor Function
• Cognitive Functions
• Reasoning, Abstract
Thinking, SelfMonitoring, Decision
Making, Planning,
Inhibition
• Organization of
Spoken Language
Frontal Motoric Areas
32
Frontal Lobe
• Cognition of motor intentions
– Input from Parietal tactile & visuospatial areas
– Active when one sees, feels, senses object and
reaches for it
– Movement for identity of unseen but felt object
– Projects to reticulospinal tract nuclei in brainstem
Broca Area – speech production
Expressive speech
Pars triangularis
(Inferior fronal gyrus)
Pars orbitalis
(Inferior frontal gyrus)
Pars opercularis
(Inferior frontal gyrus)
34
Prefrontal Cortex
•
•
•
•
•
•
•
•
•
Reasoning and judgment
Abstract thinking
Decision making
Social behavior
Important in conscious learning
Connects movement to behavior
Engaged in “working memory”
Involved in realization of consequence
Well connected to the limbic system
Parietal Lobe Landmarks
• Post Central Gyrus (PoCG)
– Primary Sensory Cortex
• Superior and Inferior Parietal
Lobules (SPL, AnG,SmG)
– Perceptual Synthesis, Spatial
Orientation, Memory
• Angular Gyrus (AnG)
Supramarginal Gyrus (SMG)
– In Dominant Hemisphere:
Reading, Writing and
Calculation
36
Parietal Lobe
• BA’s #3,1 & 2 = Primary Somatosensory Cortex
– Tactile and visuospatial
•
•
•
•
•
•
Somatosensory association
Body awareness
Stereognosis
Physical & functional identification of objects
In infant, this area requires continuous stimulation
Important area Chiropractically
The homunculus (little man)
• The motor strip (red,
frontal cortex) and
primary sensory cortex
(green, parietal) spatially
map corresponding
portions of the
contralateral hemisphere.
38
Humunculi
London Natural History Museum
Sensory and Motor Humunculae: Notice the
difference in the hands, feet, trunk and tongue.
Temporal Lobe – Major External
Gyri
• Superior Temporal Gyrus
• Middle Temporal Gyrus
• Inferior Temporal Gyri
Temporal Pole
41
Temporal Lobe
•
•
•
•
Olfactory processing
Auditory Processing
Memory Processing
Wernicke’s area
– (BA22) in left lobe
– Pathology causes nonsense speech
http://www.stroke.org.uk/research/new-research-post-stroke-aphasia
Temporal Operculum
• Dorsal surface of STG is
called the ‘Temporal
Operculum’ (Lip)
– Middle section: Heschel’s Gyri
(Brodmann Areas 41 + 42)
• Auditory Reception Cortex
– Posterior section: Wernicke’s
Area (Brodmann 22)
• Auditory Association Cortex
Heschl’s Gyrus
• Primary auditory cortex
found in Heschl’s gyrus
• This is organized
tonotopically – a high
pitched sound excites a
different region than low
pitched sounds.
44
Superior Temporal Gyrus
• Auditory Cortex lies
inside the Superior
Temporal Sulcus
• Part of the superior
temporal gyrus that is
planum temporale
imperative for the
(nonprimary AC)
Heschl’s gyrus
perception of speech is
(primary AC)
Heschl’s gyrus
planum
polare
(nonprimary
AC)
Ventral-Medial Structures
• Temporal Lobe
– Fusiform gyrys (Face
Recognition)
– Hippocampal Gyrus
(places, memory)
– Uncus (smell)
• Occipital lobe
– Cuneus and Lingual
gyrus (primary vision)
46
Medial View
Hippocampal Formation
• Located in each temporal lobe (bilateral)
• Part of the limbic system
• Involved in
–
–
–
–
memory and learning
Hypoglycemia
Anoxia
Status epilepticus (lots of damage seen here)
• Primary afferent supply is entorhinal cortex
– Smell
• Grows as for as long as learning continues
Ventral-Medial Structures
Uncus
Parahippocampal Gyrus
Fusiform Gyrus
Lingual Gyrus
Cerebellum and
Brainstem removed
48
Occipital Lobe
• Occipital Pole (medial)
– Medially: cuneus and lingual
gyrus: primary visual cortex
– Clinically: field cuts, blindsight
• Lateral occipital structures:
– Superior, Lateral and Superior
Occipital Gyris: Secondary Visual
Cortex (Association)
49
Occipital Lobe
• Visual center of the brain
– Conscious vision
– Interprets, associates, and facilitates visual images
and connects to
• Contralateral hemisphere, prefrontal cortex, parietal lobe
– Each side receives input from contralateral retina
Language Areas
51
Insular Lobe (Isle of Reil)
• Deep in Lateral Fissure
– Functions: Language(?), taste, disgust,
cravings (e.g. smoking)
Insula (Isle of Rile)
• 5th lobe of the cerebral cortex
• In the lateral cerebral fissure
• Communicates with frontal and parietal lobes
– Visceral sensory and motor and somatosensory and
somatomotor functions
•
•
•
•
Gastrointestinal and cardiac regulatory functions
Motor association area
Memory to language
Olfactory gustatory correlation
Midsagittal Surface
• Corpus Callosum
– Connects Hemispheres
• Limbic System
– Emotions
•
•
•
•
Cingulate Gyrus
Fornix
Thalamus
Hypothalamus
54
Cingulate Cortex
• Part of the limbic
system
• Surrounds the corpus
callosum
• Input from
– itself bilaterally
– Anterior thalamic nuclei
– Temporal lobe
• Part of circuit of Papez
– (see later slide)
Circuit of Papez
• hippocampal
formation (subiculum) →
• fornix →
• mammillary bodies →
• mammillothalamic tract →
• anterior thalamic nucleus→
• cingulum →
• entorhinal cortex →
• hippocampal formation
•
http://en.wikipedia.org/wiki/Papez_circuit
•
Used with permission from James Montgomery
http://montgomeryillustration.com/wp-content/uploads/2013/04/Papez.jpg
Striatum
Head of
Caudate
Nucleus
Cleft for
Internal Capsule
Thalmus
Putamen
Amygdaloid
Nucleus
Tail of
Caudate Nucleus
57
Lateral View
Midsagittal Surface
Corpus
Callosum
Cingulate
Gyrus
Septum
Uncus
Fornix
58
Transverse Slice
Fornix
Claustrum
Putamen
Caudate Nucleus
Thalamus
Globus Pallidus
59
Basal Ganglia
•
•
•
•
Caudate Nucleus
Putamen
Globus Pallidus (Pallidum)
Caudate Nucleus
+Putamen = Striatum
• Putamen + Globus
Pallidus = Lenticular
Nucleus
60
Brain Stem
Optic
Nerve
Midbrain
Pons
Medulla
Optic
Chiasm
Optic
Tract
Pes
Pedunculi
Pituitary
Stalk
61
Infant brain stem
• At birth, the most developed
area of the brain is the brain
stem.
• This controls the involuntary
reflexes: crying, rooting,
sucking, grasping, stepping,
etc.
• The Medulla controls the vital
life funcctions: breathing,
heart rate, blood pressure,
and sleep
• Brainstem also handles some
of the babies emotions: like
anxiety and calming
Midbrain, Hindbrain
• Pons
• Medulla Oblongata
• Functions: Automatic
Control Systems
63
Ventral Brainstem
•
•
•
•
•
Mamillary Bodies
Medial Sulcus
Ventral Median Fissure
Pyramidal Tract
Pyramidal Decussation
– Where signals cross
• Ventral lateral sulcus
64
Midbrain Dorsal Structures
• Superior and Inferior
Colliculus
Dorsal View of Brainstem
– The ‘little hills’.
– Superior colliculi – help Pineal Body
initiate eye movements,
integrate visual, auditory
Colliculus
and tactile information
Superior
– Inferior colliculi- audition
• Aka Corpora
Quadrigemina (four
seeds)
Inferior
Brachium
Superior
Colliculus
Inferior
Colliculus
Trochlear
Nerve
65
Cranial Nerves at Brainstem
http://web.uni-plovdiv.bg/stu1104541018/docs/res/anatomy_atlas_-_Patrick_W._Tank/7%20-%20The%20Head%20and%20Neck_files/C7FF55.jpg
66
Colliculi
• Superior colliculi: eye movement control. Also
maps touch and hearing onto vision
• Inferior colliculi: pathway for auditory
processing
Note proximityof the
colliculi and
brainstem structures
to the 4th ventricle
Sagittal View
Internal Structures of the Midbrain
•
•
•
•
•
•
Tegmentum
Cerebral Aqueduct
Red Nucleus
Cranial nerve nuclei
Reticular Formation
Central Gray Area
Transverse Section of Rostral Midbrain
Tectum
Tegmentum
Basis
Pedunculi
68
Internal structures of the pons
• Tegmentum
– Ascending and Descending Fibers
– Medial Lemniscus
• Basilar Pons
– Cortical Descending Tracts
– Pontine Nuclei
– Pontocerebellar Fibers
Transverse Section of Mid Pons
Tegmentum
Basilar
69
Medulla Oblongata
• Connects to Pontine Protrusion
• Caudal Portion Contains Pyramidal Decussation
• Where motor tracts cross over for control of contralateral
side of the body
Tegmentum
Pyramid
70
Landmarks of Medulla
• Ventral
– Ventrolateral Sulcus
– Pyramidal Tract
– Lateral Corticospinal Motor Tract
• Dorsal
– Dorsal Median Sulcus
– Dorsolateral Sulcus
– Olivary Nucleus
71
Internal Medulla
• Dorsal Tegmentum
• Ventral Pyramidal Tract
• Reticular Formation
– Cardiac Center
– Vasomotor Center
– Respiratory Center
72
Cerebellum
• Modifies Cortical Activity
• Distinctive Appearance
– Gyri called Folia
– Two Hemispheres
• Three Lobes
– Anterior
– Posterior
– Flocculonodular
73
Cerebellum
Posterior lobe
• Rostral view
– (bird’s eye)
Anterior lobe
74
Cerebellum
• Caudal view (from the feet)
Posterior lobe
Anterior lobe
75
Flocculus
Cerebellum
• Anterior view
Flocculus
Nodulus
76
Cerebellum
• Midsagittal slice
Vermis
Nodulus
Flocculus
77
Spinal Cord
• Same Meningeal Layers as the Brain
• About 45cm long
• Diameter of 1 cm.
Root filaments
Dorsal
Ventral
Pia mater
Arachnoid mater
Mixed spinal
nerve
Dura mater
78
Spinal Nerve Components
• Dorsal Division: sensory part of nerve, sensory
information enters spinal cord through dorsal
root fibers
• Ganglion: cell bodies of these nerves come
together to create the dorsal root ganglion
• Dorsal Horn or Column: information enters the
spinal column at the dorsal horn
Spinal Nerve Components
• Ventral Division: motor commands, leave the
ventral root and go to muscles
• Ventral Horn or Column: information passed
from brain to spinal cord then from the ventral
root to the extremities
Transverse view of spinal cord
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Segmental Spinal Reflex Arc
•
•
A stimulus/response system that maintains a constant state of muscular
tone
Works by:
– muscles spindles sense stretching and send information through gamma
nerves to dorsal root of spinal cord
– a signal is sent back from the ventral root for the muscle to contract
Spinal Cord
• Dorsal root fibers form ganglion
• Connect to ventral fibers to form peripheral
spinal nerves.
• Attached by Filum Terminale
83
Internal Spinal Cord
•
•
•
•
•
•
Gray Matter
Two Dorsal Horns (Sensory Info)
Two Ventral Horns (Motor Info)
White Matter
Three Myelinated Fasciculi
Dorsal, Lateral and Ventral
84
Spinal Cord Segments & Nerves
31 Spinal Segments and Nerves
Cervical
8
Lumbar
5
Thoracic
12
Coccygeal
1
Sacral
5
85
Peripheral Nervous System (PNS)
• 12 pairs of cranial nerves– Sensory, motor, or mixed
“On Old Olympus Towering Top A
Famous Vocal German Viewed
Some Hops.”
• 31 pairs of spinal nerves
Divisions of the PNS
• Somatic Nervous System (under voluntary control)
– Sensory and Motor
– Skin and Muscles
• Autonomic Nervous System (can not be voluntarily
controlled).
–
–
–
–
Sensory and Motor
Visceral organs and glands
Two main subdivisions:
Sympathetic: Fight, Flight, Fear
• Prepare to expend energy
– Parasympathetic: Regulates normal function
• Prepare to conserve energy
87
Cranial Nerves (12 pair)
I.
II.
III.
IV.
V.
Olfactory: sensory for smell
Optic: sensory for vision
Oculomotor: motor for vision
Trochlear: motor for vision
Trigeminal: sensory to eyes, nose, face and
meningies; motor to muscles of mastication
and tongue
Cranial Nerves
VI. Abducen: motor to lateral eye muscles
VII. Facial: sensory to tongue and soft palate,
motor to muscles of the face and stapes
VIII. Vestibulocochlear: sensory for hearing and
balance (aka Acoustic)
IX. Glossopharyngeal: sensory to tongue,
pharynx, and soft palate; motor to muscles
of the the pharynx and stylopharyngeus
Cranial Nerves
X.
Vagus Nerve: sensory to ear, pharynx,
larynx, and viscera; motor to pharynx,
larynx, tongue, and smooth muscles of the
viscera, 2 parts: superior laryngeal branch
and recurrent laryngeal branch
XI. Spinal Accessory Nerve: motor to
pharynx, larynx, soft palate and neck
XII. Hypoglossal Nerve: motor to strap
muscles of the neck, intrinsic and extrinsic
muscles of the tongue