Central Nervous System
List the meninges and spaces in order (from superficial to deep, or vice versa).
(from superficial to deep) dura mater, arachnoid mater, pia mater
What is the general function and location of the general interpretative area?
(i.e. Wernicke's area) involved in language comprehension; located in the junction of the temporal, parietal and occipital lobes
What is the general function and location of the prefrontal cortex?
(i.e. anterior association area) involved with intellect, cognition (complex learning abilities), recall and personality; located in the anterior portions of the frontal lobe
What are the major functions of the hypothalamus?
-controls the ANS -controls endocrine system functioning -center for emotional response -regulates body temperature -regulates eating and drinking -regulates sleep-wake cycles
What is the function of the meninges?
-cover and protect the CNS -protect blood vessels and enclose venous sinuses -contain cerebrospinal fluid -form partitions in the skull
What are the differences in sleep, specifically in sleep duration and patterns of REM & NREM sleep, in children and adults?
-daily sleep requirement declines from infancy (16 hr) to adulthood (about 7 1/2-8 1/2 hr) to old age -in infants, REM sleep makes up about 50% of total sleeping time, while in adults, REM sleep makes up only 25% of total sleeping time -duration of NREM stage 4 sleep decreases from infancy to adulthood, until it disappears completely around the age of 60
Identify the factors that can influence memory consolidation (i.e., transfer from STM to LTM) and describe their effect.
-emotional state: when we are alert, motivated, surprised or aroused, memory transfer from STM to LTM becomes more immediate -rehearsal: repetition enhances long-term memory storage -association: tying new information to old information already stored in LTM helps to remember facts -automatic memory: unconscious formation of memory
What type of efferent information is carried by the lateral corticospinal tracts? by the anterior corticospinal tracts? by the corticobulbar tracts?
-fine, skilled movements of the extremities -movement of the neck and trunk muscles -precise, voluntary movements of muscles in the face and neck
What is the function of CSF?
-makes CNS structures more buoyant -forms a liquid cushion to protect the brain and spinal cord -may help nourish the brain and carry chemical signals
Tell where each of the extrapyramidal tracts originates, and describe the general function of each.
-rubrospinal tract originates from the red nucleus of the midbrain; controls muscle tone and precise movements in distal limb muscles (especially flexors) -reticulospinal tract originates at reticular formation of brain stem; carries impulses concerned with muscle tone and various visceral motor functions -tectospinal tract originates from superior colliculus of midbrain; mediates movements of head and eyes in response to visual stimuli -vestibulospinal tract originates from vestibular nucleus in medulla; maintains muscle tone in ipsilateral limb and trunk muscles and helps mantain balance in response to head and torso movements
Name and identify the location of the four functional zones of gray matter (present on each side of the cord).
-somatic motor (SM): located in the ventral horn -visceral motor (VM): located in the lateral horn -visceral sensory (VS): located in the dorsal horn, most anteriorly -somatic sensory (SS): located in the dorsal horn, most posteriorly
Identify and describe the structures and/or materials which protect the brain & spinal cord.
1) Bone: skull protects the brain, and the vertebral column protects the spinal cord 2) Meninges: membranes; include the dura mater, arachnoid mater and pia mater 3) Cerebrospinal fluid: watery cushion found in and around the brain and spinal cord 4) Blood-brain barrier: protective mechanism that helps stabilize the internal environment of the brain
Identify and describe the characteristics of each of the stages of non-rapid eye movement (NREM) sleep. Be sure to include mention of typical EEG patterns and general physiological characteristics in your descriptions.
1) NREM stage 1: EEG shows alpha waves, and relaxation begins; "light sleep" between being awake and falling asleep 2) NREM stage 2: EEG becomes irregular with sleep spindles (short high-amplitude bursts); person begins to sleep, and body temperature drops slightly 3) NREM stage 3: EEG shows theta and delta waves appearing; deepest and most restorative form of sleep, during which vital signs decline, blood supply to muscles increases, muscles are relaxed, tissues grow and repair themselves, energy is restored and growth occurs; becomes most difficult to arouse the person from sleep 4) NREM stage 4: EEG shows delta waves; bed-wetting, nightmares and sleepwalking often occur during this stage
Identify and contrast the four frequency classes of brain wave seen in an EEG.
1) alpha waves: (8-13 Hz) indicate a state of being awake and relaxed; relatively regular and rhythmic, with low-amplitude, synchronous waves 2) beta waves: (14-30 Hz) indicate a state of being awake and alert; have a less regular rhythm and higher frequency than alpha waves 3) theta waves: (4-7 Hz) more common in children than adults; more irregular than beta waves 4) delta waves (<4 Hz) indicate deep sleep, a dampened RAS or brain damage in awake adults; high amplitude waves
Identify and describe the two most common types of neural tube defects.
1) anencephaly: failure to close the anterior neural tube 2) spina bifida: failure to close the posterior neural tube
Name and identify the function of the three different types of fiber tracts in the brain.
1) association tracts: connect different parts of the same hemisphere 2) commissural: connect corresponding gray areas of the 2 hemispheres 3) projection: can enter the cerebral cortex from the lower brain or cord centers, or descend from the cortex to lower areas
Identify and describe the function of the main visceral motor nuclei of the medulla.
1) cardiovascular center: includes cardiac center and vasomotor center; cardiac center adjusts the force and rate of heart contraction, and vasomotor center regulates blood pressure by changing blood vessel diameter 2) respiratory center: generate respiratory rhythm and control the rate and depth of breathing 3) other centers involved in vomiting, hiccuping, swallowing, coughing and sneezing
Identify and describe the main categories of long-term memory.
1) declarative memory: conscious learning of explicit information or facts 2) non-declarative memory: less conscious or unconscious learning acquired from experience and repetition
Name the neurons which comprise the ascending (i.e., sensory) pathways. Where are the cell bodies of each type of neuron located?
1) first-order neurons: cell bodies are in a ganglion 2) second-order neurons: cell bodies are in the dorsal horn of the spinal cord or in medullary nuclei 3) third-order neurons: cell bodies are the the thalamus
Identify and compare the main sub-categories of nondeclarative memory.
1) procedural (skills) memory 2 motor memory 3) emotional memory
What important structures are located in the medulla oblongata? Identify the general function of each.
1) pyramids: contain the pyramidal (corticospinal) tracts that descend from the motor cortex 2) inferior olivary nuclei: relay sensory information on the degree of stretch in muscles and joints to the cerebellum; also produce the olives (i.e. the oval swellings) 3) nucleus gracilis and nucleus cuneatus: serve as relay stations for sensory info ascending to the somatosensory cortex 4) inferior cerebellar peduncles: connect the medulla with the cerebellum 5) nuclei of cranial nerves VIII-XII
Identify the stages of memory and describe the characteristics of each.
1) short-term memory: working memory that is limited to seven or eight pieces of information; serves as the temporary storage bin for information to be transported to long-term memory 2) long-term memory: memory with a seemingly limitless capacity
Identify and tell the difference between the three types of spina bifida.
1) spina bifida occulta: "hidden" form of spina bifida; small defect in the spinal cord that is often covered by the skin; vertebral arches may be missing, but the spinal cord and meninges do not protrude through 2) meningocele: meninges surrounding the spinal cord protrude through the gap in the vertebral column, creating a small sac filled with CSF 3) myelomeningocele: both the meninges and the spinal cord protrude through the gap in the vertebral column, creating a CSF-filled sac that also contains some spinal cord and spinal roots
Describe the embryologic origins of the brain, beginning with formation of the neural plate.
1. The neural plate forms from the surface ectoderm. 2) The neural plate invaginates, forming the neural groove which is flanked by neural folds. 3) Neural fold cells migrate to form the neural crest, which will form much of the PNS and other structures. 4) The neural groove becomes the neural tube, which will form CNS structures. 5) The anterior (rostral) end of the neural tube expands and constricts to form the primary brain vesicles: the prosencephalon, mesencephalon and rhombencephalon. 6) The primary vesicles then give rise to the secondary vesicles. The prosencephalon becomes the telencephelon and diencephelon, and the rhombencephalon becomes the metencephalon and myelencephalon. The mesencephalon remains undivided. 7) Each secondary brain vesicle then gives rise to the adult brain structures. The telencephalon becomes the cerebrum, the diencephalon remains, the mesencephalon becomes the midbrain, the metencephalon becomes the pons and cerebellum, and the myelencephalon becomes the medulla oblongata.
How many periods of REM sleep (on average) does an adult experience per night?
4-5
In parts of the brain surrounding the third & fourth ventricles, the blood-brain barrier breaks down (i.e., there are relatively loose tight junctions between ependymal cells and between endothelial cells in capillary walls). We say that these regions are not "under the blood-brain barrier" and call the affected areas circumventricular organs (CVOs). What is the functional significance of the CVOs? Identify the main CVOs.
Allow bloodborne molecules easy access to neural tissue that is exposed as a result of the absence of protection from the blood-brain barrier; main CVOs are the vomiting center of the brain and the hypothalamus
What type of sensory information is carried by the anterior spinothalamic tract? by the lateral spinothalamic tract?
Anterior spinothalamic tract carries crude touch, pressure, tickle, itch and pain sensations. Lateral spinothalamic tract carries pain and temperature sensations.
Distinguish between CVAs (cerebrovascular accidents or strokes) and TIAs (transient ischemic attacks). What is the effect of each on brain function?
CVA: occurs when blood circulation to a brain area is blocked and brain tissue dies (called ischemia); as a result, brain function can be permanently lost, and common symptoms are paralysis on one side of the body (hemiplagia), sensory deficits, or difficulty understanding or vocalizing speech TIA: temporary episode of reversible cerebral ischemia; may cause temporary numbness, paralysis or impaired speech, but no permanent brain damage occurs
Describe the structure & function of a choroid plexus? Where are the choroid plexuses located?
Choroid plexuses are located in the roofs of the brain ventricles. They are clusters of capillaries enclosed internally by pia mater and externally by a layer of ependymal cells that form tight junctions and line the ventricles. Function is to produce and filter CSF.
What is a concussion? Distinguish between concussion and contusion.
Concussion: alteration in brain function following a blow to the head Contusion: more serious concussion that results in bruising of the brain
Identify the major brain structures thought to be involved in each of the main categories of LTM.
Declarative memory: association cortex, medial temporal lobe, thalamus, prefrontal cortex, basal forebrain (which releases ACh) Non-declarative memory: association cortex, basal nuclei, thalamus, premotor cortex, substantia nigra (which releases dopamine)
What are the major functions of the dominant hemisphere?
Dominant hemisphere has greater control over language abilities, math and logic.
Describe the pattern of NREM and REM sleep over one sleep period (i.e., during one night).
During the first 30-45 min of sleep, the sleeper passes from NREM stages 1 and 2 to NREM stages 3 and 4 to enter slow-wave sleep. At this point, the frequency of the EEG decreases, the amplitude increases, and the sleeper's vital signs begin to drop. Around 90 min into sleep, the sleeper then transitions from NREM stage 4 to REM sleep, during which vital signs increase, oxygen intake by the brain increases, skeletal muscles become paralyzed, and eyes begin to move rpaidly underneath the eyelids. During REM sleep, the EEG becomes very irregular and begins to backtrack back to alpha waves. Following each episode of REM sleep, the sleeper continues to alternate between NREM stage 4 and REM every 90 min.
What type of sensory information is carried by the fasciculi cuneatus? by the fasciculi gracilis?
Fasciculi cuneatus carries sensory impulses from upper limbs, upper trunk and neck. Fasciculi gracilis carries impulses from the lower limbs and lower trunk.
Locate the first-, second-, and third-order neurons of the spinothalamic tracts. Where do these tracts decussate?
First-order neurons in the dorsal root ganglia. Second-order neurons in the dorsal horn of the spinal cord. Third-order neurons in the thalamus. Tracts decussate at/near their level of cord entry.
Locate the first-, second-, and third-order neurons of the fasciculus cuneatus and fasciculus gracilis. Where do these tracts decussate?
First-order neurons in the dorsal root ganglia. Second-order neurons in the medullary nuclei. Third-order neurons in the thalamus. Decussate in the medulla.
Locate the first- and second-order neurons of the anterior and posterior spinocerebellar tracts. Explain why these tracts carry sensory information from one side of the body to the ipsilateral side of the cerebellum.
First-order neurons located in the dorsal root ganglia. Second-order neurons located in the dorsal horn. Tracts carry information to the ipsilateral side of the cerebellum, because they either do not decussate or decussate twice.
What is the role of the hypothalamus and the RAS relative to sleep and sleep-wake cycles?
Hypothalamus release orexins, which are the peptides that cause the RAS to fire impulses at maximal rates to awaken the cortex from sleep.
Identify and describe the direct (pyramidal) tracts, including location of upper and lower motor neurons of the tract and level at which decussation occurs.
Include the lateral corticospinal, anterior corticospinal and corticobulbar tracts. Lower motor neurons located in the anterior horns or the nuclei of cranial nerves in the brain stem (corticobulbar). Upper motor neurons located in the primary motor cortex and the premotor area of the frontal lobe. Nearly all fibers decussate in the medulla, and the remainder decussate at the spinal cord level where the fibers synapse.
What happens in the decussation of the pyramids?
Just above the medulla-spinal cord junction, the fibers cross over to the opposite side before continuing into the spinal cord. As a result, each cerebral hemisphere chiefly controls the voluntary movements of muscles on the opposite side of the body.
What is the major function of the thalamus? other functions?
Major function:act as the relay station for sensory input into the cerebral cortex. Other functions: key role in awareness, sensory integration, and cognition; also influences mood and motor function.
On assessment of the newborn with spina bifida, what are possible findings?
Newborn with spina bifida occulta may not present any symptoms unless shown through X-ray, but common symptoms are dimple, tuft of hair, birthmark, or fatty bulge at the site of defect. Newborn with meningocele may present a closed lesion. Newborn with myelomeningocele will present an open lesion. Pain or neurological symptoms may also occur.
What are the major functions of the non-dominant hemisphere?
Non-dominant hemisphere has greater control over visual-spatial skills, intuition, emotion, and artistic and musical skills.
What gland produces & secretes melatonin? What is the function of this hormone?
Pineal gland; melatonin is a sleep-inducing signal and antioxidant that helps regulate the sleep-wake cycle along with the hypothalamus
Identify the adult brain structures associated with each of the three primary brain vesicles.
Prosencephalon: cerebrum (including the cerebral hemispheres and basal ganglia) and diencephalon (including the epithalamus, thalamus, and hypothalamus) Mesencephalon: midbrain Rhombencephalon: pons, cerebellum, and medulla oblongata
Describe the characteristics of rapid eye movement sleep, including mention of typical EEG pattern and general physiological characteristics in your description.
REMs recur about every 90 minutes, and each consequent REM lasts longer (from 5-10 min to 20-50 min). During REM sleep, the brain becomes active, and the skeletal muscles (except the eye muscles and diaphragm) are turned off. Most dreams also occur during REM sleep. EEG pattern during REM sleep shows alpha waves.
What is the function of the nuclei of the corpora quadrigemina?
Reflex centers; the superior colliculi are reflex centers for movements of the eyes, head and neck in response to visual and other stimuli, and the inferior colliculi are reflex centers for movement of the head and trunk in response to auditory stimuli
Where are the cell bodies of motor neurons located?
Somatic motor neuron cell bodies located in the ventral horns; autonomic motor neuron cell bodies located in the lateral horns
Describe the general structure of the spinal cord, with reference to size, the gray matter, white matter, meninges and spaces.
Spinal cord is about the width of a thumb and merges with the medulla oblongata. It extends from the foramen magnum and terminates around L1 or L2 in a conus medullaris. Gray matter is located in the core of the spinal cord, and it is surrounded by white matter on the outside. Spinal cord is protected by a single layer of dura mater, arachnoid mater and pia mater. Epidural space (containing fat) surrounds the dura mater, subdural space is formed between the dura mater and arachnoid mater, and subarachnoid space (containing CSF) is formed between the arachnoid mater and pia mater.
Describe the general structure of the cerebellum.
The cerebellum is located on the dorsal surface below the occipital lobes and posterior to the pons and medulla, and it is separated from the cerebrum by the transverse fissure and the tentorium cerebelli. Its two cerebellar hemispheres are connected by the vermis, and its surface is heavily convoluted with folia. It has a thin outer cortex of gray matter, internal white matter, and small, deeply situated paired masses of gray matter. Its white matter form a branching tree pattern called the arbor vitae. The cerebellum is attached to the midbrain, pons and medulla by the superior cerebellar peduncles, middle cerebellar peduncles, and inferior cerebellar peduncles respectively.
Name the five lobes of the cerebrum and identify the sulci or fissures that separate one lobe from another.
The five lobes of the cerebrum are the frontal lobe, parietal lobes, temporal lobes, occipital lobe, and insula. The central sulcus separates the frontal and parietal lobes. The lateral sulcus separates the temporal lobe from the parietal and occipital lobes. The parieto-occipital sulcus separates the parietal and occipital lobes. And the insula is located deep within the lateral sulcus. (Note also: the longitudinal fissure divides the cerebral hemispheres, and the transverse cerebral fissure separates the cerebrum and cerebellum.)
What are the structural outcomes of the fact that the brain develops within a restricted space?
The midbrain and cervical flexures develop to tilt the forebrain toward the brain stem. The cerebral hemispheres then develop posteriorly and laterally to completely enclose the diencephalon and midbrain, and the surface of the brain forms gyri and sulci to allow for greater surface area for more neurons to be packed in the limited space.
Identify the ventricles of the brain and describe how they are connected.
Ventricles of the brain include the lateral ventricle, the third ventricle and the fourth ventricle. The lateral ventricle connects to the third ventricle via the interventricular foramen, and the third ventricle connects to the fourth ventricle via the cerebral aqueduct.
Describe the organization of the white matter of the cord.
White matter is divided into funiculi (or columns), which are further organized into ventral, lateral, or dorsal funiculi. Each funiculus contains several fiber tracts made of similar axons. These tracts are then classified based on the direction they run (ascending, descending or transverse) and named based on where they begin and end.
What is the function of the arachnoid villi?
absorbs CSF back into the dural venous sinuses
What single factor can prevent most cases of neural tube defects?
adequate intake of folate/folic acid
What structures make up the limbic system?
amygdaloid body, fornix, cingulate gyrus, parahippocampal gyrus, dentate gyrus, hippocampus, parts of several nuclei of the thalamus and hypothalamus
Identify the nonspecific ascending pathways.
anterior and lateral spinothalamic tracts
What causes the cervical and lumbar enlargements?
arising of nerves serving the upper and lower limbs from these areas
What structures comprise the basal nuclei?
caudate nucelus, putamen and globus pallidus (*putamen and globus pallidus together make up the lentiform nucleus)
What is located in the dorsal root ganglia?
cell bodies of sensory neurons
What is meant by the term hemispheric (or cerebral) lateralization? by the term cerebral dominance?
cerebral lateralization: term describing that although the cerebral hemispheres look the same, they are slightly different in structure and function cerebral dominance: designates the cerebral hemisphere that is dominant for language (i.e. contains the Broca's and Wernicke's areas)
What structures are located in the midbrain?
cerebral peduncles, superior cerebellar peduncles, corpora quadrigemina (made of the superior colliculi and inferior colliculi pairs), substantia nigra, red nuclei, and nuclei of cranial nerves III & IV
What is consciousness? How does the RAS influence consciousness?
conscious perception of sensations, voluntary initiation and control of movement, and capabilities associated with higher mental processing; clinically speaking, is defined on a continuum that grades behavior in response to stimuli as alertness, lethargy, stupor and coma. Because consciousness involves activity of the cerebral cortex, RAS contributes to consciousness.
What is the general function and location of the gustatory cortex?
consciously perceives taste stimuli; located in the insula, just above the lateral cerebral sulcus and deep to the temporal lobe
What is the function of the nuclei of the substantia nigra?
contains a high amount of the melanin pigment, which is a precursor to the neurotransmitter dopamine
What is the function of the pneumotaxic and apneustic areas?
controls the rate and depth of breathing
What is the general function and location of the primary motor cortex?
controls voluntary contractions of specific muscles or muscle groups on the contralateral side of the body; located in the precentral gyrus of each frontal lobe
What is the general function and location of the frontal eye field?
controls voluntary scanning movements of the eye; located in the frontal lobe
What are the functions of the cerebellum?
coordinates muscular activity, helps smooth skilled movements, and regulates posture and balance
What important structures are located in the pons?
deep longitudinal tracts (that connect higher brain centers and the spinal cord), middle cerebellar peduncles, nuclei of cranial nerves V-VIII, penumotaxic and apneustic centers
Identify the specific ascending pathways.
dorsal column-medial lemniscal pathways, formed by the fasciculus cuneatus, fasciculus gracilis, and the medial lemniscus
Which of the meninges adheres to the external surface of the brain & spinal cord?
dura mater
From what primary germ layer does all nervous tissue originate?
ectoderm
What cells produce CSF?
ependymal cells
What is the reticular formation? Where is it located?
functional system that extends through the central core of the medulla oblongata, pons and midbrain
What are the functions of the limbic system?
functions as the affective or emotional brain
What is the general function and location of the affective language area?
gives intonation to words to provide them meaning; located opposite Broca's area
What region of the diencephalon serves as a link between the nervous and endocrine systems?
hypothalamus
With what other structures (or regions) of the brain is the reticular formation connected?
hypothalamus, thalamus, cerebral cortex, cerebellum, and spinal cord
In what meningeal space does CSF circulate?
in the subarachnoid space
What is the general function and location of the vestibular cortex?
involved in conscious awareness of balance; located in the posterior insula
What is the general function and location of the visceral sensory area?
involved in conscious awareness of visceral sensations; located in the insula just posterior to the gustatory cortex
What is the general function and location of the premotor cortex?
involved in planning movements and controlling learned, skilled movements; located in the frontal lobe, just anterior to the precentral gyrus
What are the basal ganglia (AKA basal nuclei)?
islands of gray matter found deep within the cerebral white matter
What is located in the lateral horns?
lateral horns contain the cell bodies of autonomic motor neurons
Which is the dominant hemisphere for most people?
left cerebral hemisphere (note that this often corresponds to being right-handed)
Where is the limbic system located?
located on the medial aspect of the cerebral hemispheres and diencephalons
What is the function of the blood-brain barrier?
maintains a stable internal environment for the brain
Identify the three major regions (levels) of the brain stem.
midbrain, pons, medulla oblongata
What are the two main types of sleep?
non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep
What are the general functions of the basal nuclei?
participates in "activity selection" for motor function, cognition, learning and behavior
What is the general function and location of the auditory association area?
perceives and interprets sound; located inferior and posterior to the primary auditory cortex
What is the general function and location of the primary auditory cortex?
receives input from the cochlea (hearing apparatus) of the inner ear; located in superior part of temporal lobe, near lateral cerebral sulcus
What is the general function and location of the visual association area?
receives input from the primary visual cortex and the thalamus and interprets it using past visual experience; located in the occipital lobe surrounding the primary visual cortex
What is the general function and location of the olfactory cortex?
receives input related to smell and functions in conscious awareness of odors; located in the medial aspect of the temporal lobe
What is the general function and location of the primary visual cortex?
receives sensory input regarding shape, color and movement; located on the extreme posterior tip and on the median surface of the occipital lobe at the calcarine sulcus
What is the general function and location of the primary somatosensory cortex?
receives sensory stimuli from the contralateral side of the body; located in the postcentral gyrus of each parietal lobe
Identify the main indirect (extrapyramidal) tracts.
rubrospinal tract, reticulospinal tract, tectospinal tract, vestibulospinal tract
What is the function of the reticular activating system (RAS)?
sends continuous impulses to the cortex to keep it active and excited
What is sleep?
state of partial unconsciousness from which a person can be aroused by stimulation
What is memory?
storage and retrieval of information
What type of sensory information is carried by the spinocerebellar tracts?
subconscious proprioception (i.e. subconscious awareness of limb position in space)
What structures are included in the diencephalon?
thalamus, epithalamus, and hypothalamus
In what segmental levels of the cord are the lateral horns located?
thoracic and lumbar segments of the cord
What structural features create the blood-brain barrier?
tight junctions formed by the endothelial cells that line the capillary wall
What is the general function and location of the Broca's area?
translates thoughts into speech and controls physical speaking ability; located in the frontal lobe, just above the lateral sulcus and anterior to the inferior portion of the premotor cortex
Name the two neurons that comprise the somatic motor pathways. Where are the cell bodies of each type of neuron located?
upper motor neurons: cell bodies located in the primary motor cortex lower motor neurons: cell bodies located in either the anterior horn of the cord or in the cranial nerve nuclei of brain stem
