Central Nervous System Flashcards
CNS is composed of the ____ ___ and _____.
spinal cord and brain
- the CNS is the motor command center for planning, originating, and carrying out the transmission of messages received by PNS and organs.
CNS is enclosed within the ____ _____ and ______ _____
vertebral column; cranial structure
the most important sructure in the body for speech, language and hearing
BRAIN
- the brain is much more related than the spinal cord and his housed and protected in the cranial cavity of the skull
Key structures of the brainstem
- Midbrain
- Pons
- Medulla
Connects the spinal cord with the brain via the diencephalon;
serves as bridge between the cerebellum and all other CNS structures (incl. spinal cord, thalamus, basal ganglia, cerebrum).
The oldest part of the brain
Many cranial nerves originate from here
BRAINSTEM
Narrow structure that lis superior to the ponsand inferior to diencephalon
MIDBRAIN aka mesencephalon
part of midbrain that connects the brainstem and the cerebellum
SUPERIOR PEDUNCLES
FUNCTIONS OF MIDBRAIN
- controls many motor and sensory functions
- postural reflexes
- visual reflexes
- eye movements
- coordination of vestibular-generated eye and head movements
- contains cranial nerve nuclei for trochlear (IV) and oculomotor (III) nerves
Roundish, bulging structure that bridges the two halves of the cerebellum
- located inferior to the midbrain
- aka metencephalon
PONS
The _____ and _______ serve as a connection point between the cerebellum and various cerebral structures the inferior and middle peduncles
PONS; MIDBRAIN
Part of brainstem that transmits information relative to movement from the cerebral hemispheres to the cerebellum
PONS
- The pons contains many descending motor fibers and is involved with hearing and balance
- it also houses nuclei for the trigeminal V and facial VII nerves that are important for speech production
- aka myelencephalon
- inferior to midbrain and pons
- uppermost portion of the spinal cord
- contains all fibers that originate in cerebellum and cerebrum and move downward to form the spinal cord
MEDULLA
Functins of the Medulla
- includes several centers that control vital, automatic bodily functions, such as breathing, digestion, heart rate, and blood pressure
- facilitates many reflexes such as sneezing, coughing, blinking, vomiting
- very important for speech production because it contains descending fibers that transmit motor information to several cranial nerve nuclei
Nerve fibers contained in medulla that carry commands from the motor center of brain to various muscles
PYRAMIDAL TRACTS
- controls many movements and supply some of the muscles that are involved in speech.
- at the level of the medulla, many of these tracts crossover from left and right sides of the brain. Thus, the right side of the body is primarily controlled by the left side of the brain and vice versa
the part of the CNS that responds to incoming information by affecting the state of a person’s alertness and consciousness
RETICULAR ACTIVATING SYSTEM (RAS)
- RAS is a structure within the midbrain, brainstem, and upper portion of spinal cord
- It integrates motor impulses flowing out of the brain and sensory impulses flowing into it
Primary roles of RAS
- plays a role in execution of motor activity - sends diffuse impulses to various regions of the cortex
- and alerts cortex to incoming impulses
- primary mechanism of attention and consciousness
- arouses the cortex
- important in controlling sleep-wake cycles
- critical role in maintaining states of consciousness (sleep, drowsiness, alertness, and excitement)
Structure that lies above the midbrain and between the brainstem and the cerebral hemispheres
DIENCEPHALON
Structures of the Diencephalon
- Thalamus
- Hypothalamus
- Third Ventricle
Largest structure of diencephalon that is considered a primary sensory relay and integration center
- critical for maintenance of consciousness and alertness
- also receives motor impulses from cerebellum and basal ganglia and relays information to motor areas of cerebral cortex
- it regulates sensory information that flows into the brain and relays sensory impulses to various portions of cerebral cortex
THALAMUS
Structure of diencephalon that helps integrate actions of ANS
- controls emotions
- lies inferior to thalamus
HYPOTHALAMUS
Tall, narrow space found in diencephalon filled with CSF
THIRD VENTRICLE
structures deep within the brain, near the thalamus and lateral ventricles
- primarily composed of gray matter
- receives input primarily from the frontal lobe and relay information back to the higher centers of the brain via the thalamus
- part of the extrapyramidal system
BASAL GANGLIA
The ______________ ________ that helps regulate and modify cortically initiated motor movements, including speech
EXTRAPYRAMIDAL SYSTEM
An important part of the extra pyramidal system in which Dopamine is produced and projected to the corpus striatum
SUBSTANTIA NIGRA
- functionally related to basal ganglia but not a part of it
Neurotransmitter generated in the substantia nigra
-lack of this neurotransmitter creates motor disorders such as Parkinsonism
DOPAMINE
Signs of lesions in basal ganglia
- unusual body postures
- dysarthria
- changes in body tone
- involuntary and uncontrolled movements (dyskinesias) that interfere with person’s voluntary attempts to walk, speak, or do many other activities
Referred to as the “little brain”
- consists of two hemispheres connected separated by the vermis
- located below the cerebrum and behind the brainstem
CEREBELLUM
Large neurons found in the cerebellum, that release gamma-aminobutyric acid (GABA)
-the only output cells of the cerebellum
PURKINJE CELLS
an inhibitory neurotransmitter released by Purkinje cells crucial in the regulation and coordination of motor movements
GAMMA-AMINOBUTYRIC ACID (GABA)
Role and function of cerebellum
- regulates :
- equilibrium (balance)
- body posture
- coordinated fine motor movements
- very important to speech production because these movements are necessary for speech
A neurological disorder resulting from damage to the cerebellum
ATAXIA
- found in some people with cerebral palsy & cerebellar damage
- shows :
- abnormal gait
- disturbed balance
- speech disorder called : Ataxic Dysarthria
- creates other communication disorders
biggest most important CNS structure for language, speech, and hearing
- complex structure of intricate neural connections with 10-15 billion neurons
- weighs about 3 lbs.
CEREBRUM/CEREBRAL CORTEX
Lobes of Cerebrum
- FRONTAL
- PARIETAL
- OCCIPITAL
- TEMPORAL
named based on cranial bones they are in contact with.
Gray matter or cells are inside the cerebrum
T/F
False
Gray matter is on the top of the cerebrum but inside the spinal cord and brainstem
Ridge on the cortex
GYRUS
A shallow valley on the cortex
SULCUS
-there are many sulci on the surface of the brain
Deeper valleys of the brain
FISSURES
- boundaries between the broad divisions of the cerebrum
- there are fewer fissures than sulci
Fissures of the brain
-
Longitudinal - runs along teh middle of the brain from front to back
- divides the cerebrum into left and right hemispheres
- deep and extends down to corpus callosum
-
Central Sulcus (Fissure of Rolando) - runs laterally, downward and forward
- divides the anterior from posterior half of brain
-
Sylvian Fissure (lateral cerebral fissure) - starts at inferior portion fo the frontal lobe at base of brain and moves laterally and upward
- Areas of brain surrounding Sylvian fissure are critical in speech, language and hearing
Lobe critical to deliberate formation of plans an intentions that dictate a person’s conscious behavior
FRONTAL LOBE
People who have difficulty carrying out consciously organized activity may have damage to the ______lobe
FRONTAL
FRONTAL LOBE AREAS CRITICAL TO SPEECH PRODUCTION
- Primary motor cortex
- Supplementary Motor Cortex
- Broca’s area
Area of frontal lobe that controls voluntary movements of skeletal muscle on opposite side of body (contralateral motor control)
PRIMARY MOTOR CORTEX (MOTOR STRIP)
- located on the precentral gyrus anterior to centeral sulcus
- all muscles including those for speech production are connected here
- specific regions that are stimulated correspond with motor responses of that area (e.g. movement of hand)
- large area represents the larynx, jaw, tongue and lips = importance in cortical control of speech-related structures
- controls muscle movements through neural pathway called pyramidal system
Part of frontal lobe believed to be involved with motor planning of speech
-plays secondary role in regulating muscle movements
SUPPLEMENTARY MOTOR CORTEX
Part of frontal lobe known as the “speech center” and motor speech area
-controls motor movements involved in speech production
BROCA’S AREA
- located on left inferior frontal gyrus
- damage/lesions to this area cause motor speech problems
The primary somatic sensory area
- integrates contralateral somatic sensations like pressure, pain, temperature and touch
- integrates information with other areas, predominantly with vision
PARIETAL LOBE
Gyrus that integrates and controls somatic sensory impulses
-lies just behind the central sulcus
POST CENTRAL GYRUS
aka sensory cortex or sensory strip
2 areas of parietal lobe important for speech and language
- supramarginal gyrus
- angular gyrus
Damage to this gyrus can cause conduction aphasia and agraphia (a writing disorder)
SUPRAMARGINAL GYRUS
-lies superior to lateral fissure in the inferior portion of the parietal lobe; posterior
Damage to this gyrus can cause writing, reading, and naming difficulties and, in some cases, transcortical sensory aphasia
ANGULAR GYRUS
Lobe primarily concerns with receiving and processing visual information
OCCIPITAL LOBE
Lobe that lies inferior to frontal and parietal lobes and in front of the occipital lobe
- Contains two general areas critical to adequate hearing and speech
a. Primary Auditory Cortex
b. Auditory association area - Also contains Wernicke’s area
TEMPORAL LOBE
Part of temporal lobe that receives sound stimuli from acoustic nerve CN VIII
PRIMARY AUDITORY CORTEX
Area in temporal lobe that receives sound stimuli from primary auditory cortex, then synthesizes it so that it can be recognized as whole units
AUDITORY ASSOCIATION AREA
- Dominant Hemisphere (left in most people) - analyzes speech sounds so that the person recognizes words and sentences
- Nondominant Hemisphere (right hemisphere, for most people) - analyzes nonverbal sound stimuli such as environmental noises, music and prosody (e.g. stress rate, rate, melody)
Important area within left temporal lobe that is critical to comprehension of spoken and written language
-Connected to Broca’s area through the arcuate fasciculus
WERNICKE’S AREA
Lesions in his area of the temporal lobe produces fluent but meaningless speech and significant language comprehension problems
WERNICKE’S AREA
Part of temporal lobe responsible for recalling information and storing long-term memories.
HIPPOCAMPUS
- Lesions to this area can result in anterograde amnesia (inability to create new memories) or retrograde amnesia ( inability to remember memories prior to lesion)
the direct motor activation pathway that is responsible for facilitating voluntary muscle movement (including speech)
[responsible for carrying the impulses that control voluntary fine movements]
PYRAMIDAL SYSTEM
The nerve fiber tract of the pyramidal system comes from the _____ _____ to the spinal cord and brainstem to supply the muscles of the head, neck, and limbs
CEREBRAL CORTEX
- Voluntary movements needed to produce speech are initiated in the primary motor cortex.
Parts of pyramidal system
- Corticobulbar - Critical to speech production
- controls all voluntary movements of speech muscles (except respiratory muscles)
- terminates in the brainstem
- Corticospinal tracts - terminate in the spinal cord
- Both are further subdivided into :
Lower Motor Neurons
- efferent nerves that result in muscular movement; part of the PNS
Upper Motor Neurons
- efferent nerves within CNS; incude pathway sof both pyramidal and extrapyramidal systems
transmits impulses that control the postural support needed by fine motor movements
-helps maintain posture and tone and regulate the movement that results from lower motor neuron activity
EXTRAPYRAMIDAL SYSTEM
- “extra” refers to the motor tracts that are not part of the pyramidal system
- composed ot differenct subcortical nuclei incudeing red nucleus, substantia, nigra, subthalamus, basal ganglia, and pathways that connect these structures together
- indirect activation system that interacts with various motor systems in the nervous system
Damage to this system creates motor disturbances that fall under “involuntary movement disorders”
-patients may show unusual movement patterns of variuos muscles (including facial muscles) and bizarre postures
EXTRAPYRAMIDAL SYSTEM
Bundle of fibers that connect Broca’s area with Wernicke’s area
ARCUATE FASCICULUS
- important for verbal memory, language acquisition, meaningful language production, and repetition.
- Damage to this structure can cause conduction aphasia
Type of aphasia that can be caused by damage to arcuate fasciculus in which there are little to no receptive and expressive langauge deficits but individual is unable to repeat language presented auditorily
CONDUCTION APHASIA
Fibers that connect areas within the same hemisphere & maintains communication between the structures in a hemisphere
ASSOCIATION FIBERS
Fibers that connect between the cortex and subcortical structures like the cerebellum, basal ganglia, brainstem and spinal cord
PROJECTION FIBERS
Fibers that are interhemispheric connectors that connect corresponding areas of the two hemispheres
COMMISURAL FIBERS
- Most Important is Corpus Callosum
Corpus Callosum
thick broad band of myelinated fibers that connect the two hemispheres at their base
Signs of damage to corpus callosum
- damage disconnects the two hemispoheres resulting in dysconnection syndromes, characterized by problems in naming, reading, movement and other functions
Cerebral Ventricles
System of cavities deep within the brain filled with CSF
Four Cerebral Ventricles
- Two lateral ventricles (largest )- one in each hemisphere
- Third ventricle - behind lateral ventricles at top of brainstem
- Fourth Ventricle- between cerebellum and pons and continuous with teh central canal of the spinal cord below and cerebral aqueduct
Produces CSF
choroid plexus
Connects the fourth and third ventricles
CEREBRAL AQUEDUCT
Four branches aortic arch divides into
2 carotid
2 subclavian
Arteries that branch out from aortic arch and supply the upper extremities
SUBCLAVIAN ARTERIES
Arteries that branch out from the two subclavian arteries
Vertebral Arteries
- enters the skull and branches out to supply the spinal cord and many organs of body
As vertebral arteries move up to lower level of pons, they join to form the _____ _____
BASILAR ARTERY
As basilar artery moves toward upper portion of pons, it divides into two _______ ____ ____
POSTERIOR CEREBRAL ARTERIES
- they supply the lateral and lower portions of the temporal lobes adn lateral and middle portions of occipital lobes
Carotid artery that supplies blood to muscles of the mouth, nose, forehead and face
EXTERNAL CAROTID ARTERIES
Carotid artery that is major supplier of blood to the brain
INTERNAL CAROTID ARTERY
- Has 2 key branches:
- Middle Cerebral Artery
- Anterior Cerebral Artery
Biggest branch of internal carotid artery branch that supplies the entire lateral surface of cortex, including major regions of frontal lobe
MIDDLE CEREBRAL ARTERY
- Supplies blood to major areas involved with motor and sensory functions and language, speech and hearing functions.
Damage to middle cerebral artery may result in:
- strokes - causing aphasia, reading and writing deficits
- contralateral hemiplegia
- impaired sense of pain, temperature, touch and position
Carotid Artery that supplies the middle portion of the parietal and frontal lobes, corpus callosum, and basal ganglia
ANTERIOR CEREBRAL ARTERY
Damage to anterior cerebral artery can cause
- cognitive deficits
- impaired judgement, concentration, reasoning
- paralysis of feet and legs
Connections between arteries formed at base of brain where the two carotid and vertebral arteries join
- provides a common blood supply to various cerebral branches
CIRCLE OF WILLIS
If artery is blocked above Circle of Willis, brain damage (will/will not) occur because brain has no alternate source of blood
will
If artery is blocked below the circle of Willis, brain damage may be minimal because alternate channgels of blodo flow may be maintained or compensate for the lack of blood flow
T/F
TRUE
