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

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

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

“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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

“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

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

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

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

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

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

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

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

SPPA 2050 Speech Anatomy & Physiology

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

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

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

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

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

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

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

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

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

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

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

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

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

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

SPPA 2050 Speech Anatomy & Physiology

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

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

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

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

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

SPPA 2050 Speech Anatomy & Physiology

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

SPPA 2050 Speech Anatomy & Physiology