The Central Nervous System

The Central Nervous System
SPPA 2050 Speech Anatomy & Physiology

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

Outline Anatomy of the Nervous System Central Nervous System Peripheral Nervous System Nourishment and Protection SPPA 2050 Speech Anatomy & Physiology

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

Basic CNS Organization
Spinal cord Brain Hindbrain Medulla Pons Cerebellum Midbrain Forebrain Thalamus Hypothalamus Basal ganglia Cerebrum SPPA 2050 Speech Anatomy & Physiology

Spinal cord Brain Hindbrain Medulla Pons Cerebellum Midbrain Forebrain Thalamus Hypothalamus Basal ganglia Cerebrum brainstem SPPA 2050 Speech Anatomy & Physiology

CNS is made up of gray matter and white matter
Basic CNS Organization CNS is made up of gray matter and white matter SPPA 2050 Speech Anatomy & Physiology

White matter Contains axons that communicate between CNS structures Why white? Contains myelin (which is fatty) which insulates axons When you think white matter, think connections between brain regions. SPPA 2050 Speech Anatomy & Physiology

Gray matter contains cell bodies and synapses that allow communication between neurons. Place of integration/modulation of CNS activity. Nucleus: collection of CNS cell bodies When you think gray matter, think cell bodies & synapses between individual neurons. SPPA 2050 Speech Anatomy & Physiology

White and gray matter Transverse Section of Brain Gray matter
White matter, Transverse Section of Brain SPPA 2050 Speech Anatomy & Physiology

White and gray matter Cross-Section of Caudal Brainstem Gray matter,
which stains light White matter, which stains dark (Weigert stain) Cross-Section of Caudal Brainstem SPPA 2050 Speech Anatomy & Physiology

The CNS is generally “symmetric” sinistral dextral Cross-Section of Brainstem (Level 3) 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

Cerebral Hemispheres When viewing the whole brain, it is the cerebral cortex that is most visible. It dominates the rest of the brain in size and function and is most developed in humans. Its wrinkled appearance is intentional and allows for a lot of surface area to be fit into a relatively small space. SPPA 2050 Speech Anatomy & Physiology

Cerebral Hemispheres Largest part of the brain wrinkled surface or cortex (bark) ↑ ↑ ↑ surface area Principally gray matter (synapses) organized in layers SPPA 2050 Speech Anatomy & Physiology

Cerebral Cortex: Basic Structure Unlike the brainstem and spinal cord, where white matter surrounds the gray matter, the cerebral cortex is organized with the gray matter being superficial (close to the surface) to the white matter. It is the location of this gray matter that gives this structure the name cortex, which mean bark. Microscopically, the cortex is a layered structure. Moving from superficial to deep, there are six different layers, each with a different cell type. The thickness of the layers varies across surface of the cortex. These structural variations were studied in detail by a scientist named Brodmann, who found a large number (52) of distinct regions of the brain. He used numbers to identify these areas and this has become a convention used by neuroscientists with which to converse about the cortex. The folds in the cortical surface give rise to gyri (singular= gyrus) and sulci (singular=sulcus). A gyrus is the ridge in the fold. A sulcus is a depression in the fold. A large depression is often called a fissure. Particular sulci and gyri serve as useful landmarks for identifying functional areas of the cortex. There are three important sulci/fissures that serve to divide the cerebral cortex into different parts. SPPA 2050 Speech Anatomy & Physiology

Cerebral Cortex: Basic Structure
Gyrus outfolding of cortex Sulcus/fissure infolding of cortex SPPA 2050 Speech Anatomy & Physiology

Cerebral Hemispheres Longitudinal fissure SPPA 2050 Speech Anatomy & Physiology

Lobes of Cerebral Cortex
There are four major lobes in the cerebral cortex. The cerebrum has other lobes (e.g. the limbic lobe), but these are part of evolutionarily older brain regions and can be considered functionally distinct. Anterior the the central sulcus and superior to the lateral sulcus is the frontal lobe. Posterior to the central sulcus and superior to the lateral sulcus is the parietal lobe. Inferior to the lateral sulcus is the temporal lobe. The posterior part of the cortex is the occipital lobe. The occipital lobe is concerned mainly with vision, so we will not discuss this cortical region in any detail. SPPA 2050 Speech Anatomy & Physiology Figure 39.12

Insula: Lobe or region? SPPA 2050 Speech Anatomy & Physiology

Sulci & Brodmann Areas SPPA 2050 Speech Anatomy & Physiology Figure 39.11

Relation between anatomy and function
Kent (1997) SPPA 2050 Speech Anatomy & Physiology

Communicating between brain structures
Performed by axonal fibers (i.e. white matter) Fasciculi – bundles of axonal fibers SPPA 2050 Speech Anatomy & Physiology

Communicating between brain structures
Types of fibers Association fibers connect cortical areas in the same hemisphere short (i.e. gyrus to next gyrus) long (i.e. connecting lobes) Commissural fibers connect hemispheres Projection fibers Projects to/from the brainstem and spinal cord SPPA 2050 Speech Anatomy & Physiology

Some fasciculi of the cerebral cortex (long association fibers)
Kent (1997) SPPA 2050 Speech Anatomy & Physiology

Commissural fibers of the cerebral cortex
Corpus callosum Anterior commissure Middle commissure Posterior commissure Figure 39.31 SPPA 2050 Speech Anatomy & Physiology

Corona radiata & internal capsule
Figure 39.8 SPPA 2050 Speech Anatomy & Physiology

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

Basal ganglia (nuclei)
SPPA 2050 Speech Anatomy & Physiology

A collection of nuclei including caudate nucleus putamen globus pallidus subthalamic nucleus substantia nigra putamen + globus pallidus = lentiform nucleus caudate nucleus + putamen = corpus striatum SPPA 2050 Speech Anatomy & Physiology

Caudate nucleus body head tail Lentiform nucleus Netter SPPA 2050 Speech Anatomy & Physiology

Figure 39.7 Coronal Figure 39.9 Transverse SPPA 2050 Speech Anatomy & Physiology

Function involved in movement control Does not directly connect to motorneurons Helps stabilize the motor system Diseases Parkinson’s Disease reduced movement Huntington’s Chorea uncontrolled “dancing” like movement Hemiballismus Uncontrolled rapid movements SPPA 2050 Speech Anatomy & Physiology

Thalamus SPPA 2050 Speech Anatomy & Physiology

Thalamus Figure 39.7 Coronal Figure 39.9 Transverse SPPA 2050 Speech Anatomy & Physiology

Thalamus Figure 39.16 SPPA 2050 Speech Anatomy & Physiology

Thalamus Netter SPPA 2050 Speech Anatomy & Physiology

Thalamus Basic Anatomy Is a collection of nuclei All sensory information (exception olfaction) passes through thalamus en route to cerebral cortex Information from basal ganglia and cerebellum reaches cortex via the thalamus “gateway to the cortex” Function integration site for Sensory information from different modalities Complex behavior (language) Motor processes Emotional circuits SPPA 2050 Speech Anatomy & Physiology

Thalamic nuclei Anterior & mediodorsal nuclei Connected to emotional circuits Ventral anterior and ventral lateral nuclei input from basal ganglia and cerebellum Ventral posterior lateral (VPL) and medial (VPM) relays general sensory information from body (VPL) and head (VPM) Medial geniculate body Relays/processes auditory information Lateral geniculate body Relays/processes visual information SPPA 2050 Speech Anatomy & Physiology

Hypothalamus Figure 39.16 SPPA 2050 Speech Anatomy & Physiology

Hypothalamus Basic Anatomy Located inferior to the thalamus (hence “hypo”) Function Controls ‘autonomic behavior such as release of hormones control of food and water intake sexual behavior sleep cycles emotional responses Indirect role in speech (unless you include flirting) SPPA 2050 Speech Anatomy & Physiology

Cerebellum SPPA 2050 Speech Anatomy & Physiology Figure 39.6

Cerebellum & Brainstem
SPPA 2050 Speech Anatomy & Physiology Figure 39.6

Cerebellum Cerebellum ~ “little brain” Contains ~ ½ neurons in the entire brain Attached to dorsal brainstem by peduncles Inferior cerebellar peduncle middle cerebellar peduncle superior cerebellar peduncle SPPA 2050 Speech Anatomy & Physiology

Cerebellar peduncles (new slide)
Figures 39.16,39.18 SPPA 2050 Speech Anatomy & Physiology

Cerebellum White matter Fibers going into and out of the cerebellum via peduncles Gray matter Cerebellar cortex deep cerebellar nuclei SPPA 2050 Speech Anatomy & Physiology

Cerebellar gray matter (new slide)
SPPA 2050 Speech Anatomy & Physiology From Netter

Cerebellum Cerebellar cortex What is it? Primary information receiving area How is information received? Inferior and middle cerebellar peduncles Where does the information come from? other motor control centers vestibular system (balance) Information about body position via brainstem and spinal cord SPPA 2050 Speech Anatomy & Physiology

Cerebellum Deep Cerebellar Nuclei What is it? Primary information sending area How does it send information? superior cerebellar peduncle Where does it send information? brainstem and spinal cord Cerebral cortex via thalamus SPPA 2050 Speech Anatomy & Physiology

Cerebellum Function Coordinates muscles for smooth fluid motion Monitors “state” of body in space Monitors/adjusts motor commands Cerebellar Disease/damage can result in “ataxia” Decomposition of movement Errors in timing and scaling of movement Tremor during movement activities SPPA 2050 Speech Anatomy & Physiology

Limbic System SPPA 2050 Speech Anatomy & Physiology

Limbic System Hippocampus Fornix Mammillary body Amygdala SPPA 2050 Speech Anatomy & Physiology Figure 39.13

Limbic System Function Important in regulating emotional and visceral responses role in speech/language unclear damage in the area can cause mutism (lack of any speech) SPPA 2050 Speech Anatomy & Physiology

Brainstem: ventral Midbrain Pons Medulla SPPA 2050 Speech Anatomy & Physiology Figure 39.19

Brainstem: Dorsal Lateral
Midbrain Pons Medulla Figure 39.19 SPPA 2050 Speech Anatomy & Physiology

Brainstem: dorsal Midbrain Pons Medulla Figure 39.19 SPPA 2050 Speech Anatomy & Physiology

Brainstem Basic Anatomy Contains Projection fibers (called tracts) To higher CNS structures from SC/BS To SC/BS from higher CNS structures Nuclei Associated with cranial nerves Associated with basic bodily function SPPA 2050 Speech Anatomy & Physiology

Brainstem Function Cranial nerve nuclei Motor supply to muscles of speech Sensory supply to head and neck Regulates some essential life functions Body temperature Respiration Swallowing Digestion SPPA 2050 Speech Anatomy & Physiology

Figure 39.19

Superior orbital fissure (CN V: ‘V1’) Foramen rotundum (CN V: ‘V2’) Foramen ovale (CN V: ‘V3’) Internal auditory meatus (CN VII & VIII) Jugular foramen (CN IX, X, XI) Hypoglossal canal (CN XII) SPPA 2050 Speech Anatomy & Physiology

Cranial Nerve Nuclei SPPA 2050 Speech Anatomy & Physiology Figure 31.2

Where do cranial nerves arise?
Pons CN V – sourced to a number of BS nuclei CN VII –motor portion from Facial nucleus Medulla CN IX, X, XI – originate largely in nucleus ambiguus CN XII – originates in Hypoglossal nucleus SPPA 2050 Speech Anatomy & Physiology

The Central Nervous System

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