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119 Cards in this Set

  • Front
  • Back
From what primary germ layer does all nervous tissue originate?
Ectoderm
Identify the adult brain structures associated with each of the three primary brain vesicles.
- Prosencephalon (forebrain)
- Mesencephalon (midbrain )
- Rombencephalon (hindbrain)

These are created when the anterior part of neural tube differentiates
Remainder turns into spinal cord
What are the structural outcomes of the fact that the brain develops within a restricted space?
1 - Midbrain and cervical flexures (they bend down)
2 - Posterior and lateral growth of the cerebral hemispheres (so that it completely encloses the brain stem)
3 - Surface convolutions (sulci and gyri); grooves increase surface area, pack more neurons into less space; fissures
Be able to describe the embryologic origins of the brain, beginning with formation of the neural plate.
- Make sure you look at notes - this card is not complete
Ectoderm thickens forming neural plate
Neural tube invaginates, surrounded by edges (neural folds) and when they fuse = neural tube
Off to the side there are 2 pinched off parts called neural crest (turns into part of PNS)
Anterior neural tube - forms primary brain vesicles, which become secondary brain vesicles, which turn into adult brain structures;
Central cavity (neurocoel) turns into 4 ventricles
!!!see notes!!!
Neural Plate
Thickened part of ectoderm that forms during the 3rd week
Origin of all neural tissue
Invaginates to become neural tube
Neural tube
The neural plate, once it is fully invaginated, and the neural folds fuse together
Filled with fluid - central cavity called neurocoel
It's formation is called neurulation
Prosencephalon
Primary brain vesicle (1 of 3) - the forebrain
Forms secondary vesicles -
- telencephalon (will be cerebrum - cerebral hemispheres and basal ganglia)
- diencephalon (epithalamus, thalamus, hypothalamus)
Mesencephalon
Primary brain vesicle (1 of 3) - the midbrain
Does not subdivide into secondary brain vesicles
Develops into midbrain (surrounds cerebral aqueduct)
Rhombencephalon
Primary brain vesicle (1 of 3) - the hindbrain
Forms secondary vesicles -
- Metencephalon (will become pons and cerebellum - houses part of 4th ventricle)
- Myelencephalon (will becom medulla oblongata - houses remainder of 4th ventricle)
Telencephalon
A secondary brain vesicle
Derived from Prosencephalon
Becomes cerebrum (cerebral hemispheres and basal ganglia)
Diencephalon
A secondary brain vesicle
Develops from Prosencephalon
Becomes epithalamus, thalamus, hypothalamus (structures that surround the 3rd ventricle)
Metencephalon
A secondary brain vesicle
Develops from Rhombencephalon
Becomes pons and cerebellum (houses part of 4th ventricle)
Myelencephalon
A secondary brain vesicle
Develops from Rhombencephalon
Becomes medulla oblongata (houses remainder of 4th ventricle)
Spina bifada
Failure to close of the posterior (caudal) neural tube
Usually not fatal
Anencephaly
Failure to close of the anterior neural tube
Almost always fatal
Dura mater
Protection and covering of the brain
Part of meninges
Tough outer layer
Where it surrounds the brain, made up of 2 layers
- Superficial layer fused to periosteum on inner surface of cranial bones
- Meningeal layer forms true external meninx of brain - continuous with dural sheath of spinal cord
Usually fused together, when separate = dural sinuses that channel venous blood from brain to internal jugular veins in neck
Extends in to make partitions to limit internal brain movement: falx cerebri, falx cerebelli and tentorium cerebelli
Pia mater
Protection and covering of brain
Part of meninges
Transparent inner layer which adheres to external surface of brain and cord
Cranial meninges
- Dura mater (hard outer layer)
- Sub-dural space (beneath dura; film of fluid)
- Arachnoid/arachnoid matter (middle layer)
- Subarachnoid space (web like membrane extensions and Cerebrospinal fluid)
- Pia mater (inner layer)
Arachnoid (or arachnoid matter)
Part of meninges
Thin, transparant, middle layer
Falx cerebri
Part of the dura mater (outer layer of meninges) when it extends inward to form partitions which limit brain movement in cranium
- dips into longitudinal fissure
- attaches anteriorly to crista galli of ethmoid bone
Tentorium cerebelli
Part of the dura mater (outer layer of meninges) when it extends inward to form partitions which limit brain movement in cranium
- extends into transverse fissure
- separates and supports cerebrum and cerebellum
Falx cerebelli
Part of the dura mater (outer layer of meninges) when it extends inward to form partitions which limit brain movement in cranium
- small midline partition that runs along the vermis of the cerebellum
Subarachnoid space
Part of the cranial meninges
Surround and protect the brain
Deep to the arachnoid, superficial to the pia mater
Web like membrane extensions span it, connecting w/arachnoid and pia mater
Space where CSF (cerebrospinal fluid) circulates completely around brain and spinal cord
Identify the ventricles of the brain and describe how they are connected.
Lateral ventricles (paired) - C shaped, one in each hemisphere
Third ventricle - thin vertical slit in midline of diencephalon, communicates with fourth ventricle via cerebral aqueduct
Fourth ventricle - between brain stem and cerebellum, continuous with central canal of spinal cord
Lateral ventricles - interventricular foramen - third ventricle - cerebral aqueduct - fourth ventricle (with median and lateral apertures - where fluid leaks to subarachnoid space in meninges) - central canal
Name the five lobes of the cerebrum.
- Frontal
- Parietal
- Temporal
- Occipital
- Insula (the deep one)
Identify the sulci that separate one lobe from another.
Central sulcus - separates frontal lobe and parietal lobe
Parieto-occipital sulcus - separates occipital love and parietal lobe (on medial surface of hemisphere)
Lateral sulcus - separates temporal lobe from parietal and frontal lobe
Precentral gyrus
Elevated ridge of tissue that borders the central sulcus (which separates frontal and parietal lobes) anteriorly
Postcentral gyrus
Elevated ridge of tissue that borders the central sulcus (which separates frontal and parietal lobes) posteriorly
Identify the fissures that separate one lobe from another.
Longitudinal fissure - separates cerebral hemispheres
Transverse cerebral fissure - separates cerebral hemispheres from cerebellum
What is the function of the meninges?
Surround and protect brain and spinal cord
Made of 3 layers of tissue separated by spaces or potential spaces
Dura mater - subdural space - arachnoid - subarachnoid space (with CSF) - pia mater
List the meninges and spaces in order (from superficial to deep).
- Dura mater (tough outer layer) - superficial and meningeal layer
- Sub-dural space - thin fluid layer
- Arachnoid - thin transparant
- Subarachnoid space - CSF circulates
- Pia mater - transparent inner layer
In what meningeal space does CSF circulate?
Subarachnoid space
Which of the meninges adheres to the brain?
Pia mater - transparent inner layer
What is the function of CSF?
Circulation - nourish the brain
Chemical protection - difft. composition from plasma of blood (more Na Cl H, less Ca K)
Mechanical protection - reduces brain wt., protects from shock
Describe the structure and function of a choroid plexus.
Network/clusters of capilaries
Hang from roof of ventricles
Covered by ependymal cells
Have ion pumps to modify filtrate from bloodstream
- They produce CSF!
Where are choroid plexuses located?
Hang from roof of ventricles, covered by ependymal cells
What cells produce CSF?
Choroid plexus
Broad thin walled capillaries
Hang from roof of ventricles, enclosed by pia mater and layer of ependymal cells lining the ventricle
Ependymal cells have tight junctions and ion pumps to modify the filtrate
Describe the path of CSF circulation, beginning at the lateral ventricles.
- Lateral ventricles
- through interventricular foramen to third ventricle
- Through cerebral/mesencephalic aqueduct to fourth ventricle
- To the subarachnoid space (through 3 openings in roof of 4th ventricle, median aperture, 2 lateral apertures)
- Circulates in subarachnoid space until reabsorbed in blood vascular sinuses (through arachnoid villi)
What is the function of the arachnoid villi?
Reabsorbs CSF from subarachnoid space into blood vascular sinuses
What structural features create the blood brain barrier?
- Tight junctions between adjacent epithelial cells in walls of cerebral capillaries
- Astrocyte processes (supply signals to endothelial cells, causing them to make the tight junctions)
What is the function of the blood-brain barrier?
- Inhibits passage of materials from systemic circulation into brain tissue
- Brain needs constant internal environment - otherwise with chem variation, neurons would fire incontrollably, since many of the chem are used as NTs
What is the functional significance of the circumventricular organs (CVOs)?
Identify the main CVOs.
- Hypothalamus, pituitary, pineal gland, etc
- Monitor changes, and coordinate homeostatic activities in response to changes in blood chemistry
What is the general function of the primary motor cortex?
- Controls voluntary contractions of specific muscles/groups of muscles on opposite side of body
- Skeletal muscles
What is the general function of the premotor cortex?
- Planning movement
- Controlling learned movements like playing scales
What is the general function of Broca's area?
- The motor speech area
- Translating thoughts to speech
- Damage = non-fluent aphasia; know what to say but can't get it out of your mouth
What is the general function of the frontal eye field?
- Voluntary scanning movements of the eye
- Scanning a page
- Damage = trouble reading b/c eyes can't track
What is the general function of the primary auditory cortex?
- input from cochlea of inner ear
- Interprets pitch, rhythm, loudness, location
- Basic premises of sound
What is the general function of the auditory association area?
- Perception/interpretation of sound
- memories of previous auditory experiences so we can identify it
- speech interpretation
What is the general function of the vestibular cortex?
- conscious awareness of balance
- input from vestibular apparatus (semicircular canals) in ear
What is the general function of the prefrontal cortex?
- anterior association area
- very complicated processing involved with intellect and complex learning
- personality, conscience, abstract thinking, (mood and emotions somewhat)
- undeveloped in children
What is the general function of the general interpretative area?
- includes Wernicke's area and gnostic area
- all of the association areas converge into this area
- vital for intellectual functioning
- Damage = you could read a paragraph, but have no idea what thoughts were being conveyed
What is the general function of the primary smoatosensory cortex?
- recieves sensory stimuli (from somatic sensors in skin and proprioceptors in joints and muscles) from the opposite side of body
- Spatial discrimination (we know what part of the body is being stimulated
What is the general function of the somatosensory association area?
- integrating and interpreting sensory inputs (touch, press, temp)
- w/o looking, you can know where your foot is
What is the general function of the prinary visual cortex?
- sensory input regarding shape, color, movement
- from rods and cones in eyes
What is the general function of the visual association area?
- Input from primary visual cortex and thalamus
- interpret info; know you're looking at a person, at your friend
What is the general function of the olfactory cortex?
- Input related to smell; conscious awareness of odors
- part of the rhine encephalon
What is the general function of the gustatory cortex?
- taste stimuli are consciously perceived
What is the general function of the affective language area?
- a posterior association area (along with the general interpretative area/wernicke's area and gnostic area)
- nonverbal, emotional components of language
- Damage = can't read emotion in a sentence like "I was in a car accident and my husband was killed" "oh that's too bad"
Within what lobe or region of the cerebrum is the prime mary motor cortex located in?
- precentral gyrus of each frontal lobe
- contains pyramidal cells
- large motor neurons; long axons; creates corticospinal/pyramidal tracts
Within what lobe or region of the cerebrum is the premotor cortex located in?
- frontal lobe
- just anterior to precentral gyrus
- communicates w/basal nuclei
Within what lobe or region of the cerebrum is Broca's area located in?
- frontal lobe
- just above lateral sulcus
- anterior to inferior portion of premotor cortex
- lateralized to left hemisphere
Within what lobe or region of the cerebrum is the frontal eye field located in?
- frontal lobe
Within what lobe or region of the cerebrum is the prinary auditory cortex located in?
- superior part of temporal lobe
- near lateral cerebral sulcus
Within what lobe or region of the cerebrum is the auditory association area located in?
- inferior and posterior to primary auditory cortex
Within what lobe or region of the cerebrum is the vestibular cortex located in?
- posterior insula
Within what lobe or region of the cerebrum is the prefrontal cortex located in?
- anterior portions of frontal lobes
Within what lobe or region of the cerebrum is the general interpretative area located in?
- posterior end of the lateral sulcus
- where all difft association areas converge
- 1 hemisphere only (usu. left hem. in right handed ppl)
Within what lobe or region of the cerebrum is the primary somatosensory cortex located in?
- postcentral gyrus of each parietal lobe
- get stimuli from opposite/contralateral side of body
Within what lobe or region of the cerebrum is the somatosensory association area located in?
- just posterior to primary somatosensory cortex
Within what lobe or region of the cerebrum is the primary visual cortex located in?
- extreme posterior tip
- medial surface of occipital lobe at calcarine sulcus
- note:medial surface of occipital lobe is in the longitudinal fissure
Within what lobe or region of the cerebrum is the visual association area located in?
- surrounds primary visual cortex in occipital lobe
- input from primary visual cortex and thalamus
Within what lobe or region of the cerebrum is the olfactory cortex located in?
- primarily in medial aspect of temporal lobe
Within what lobe or region of the cerebrum is the gustatory cortex located in?
- mainly in the insula
- just above lateral cerebral sulcus
- deep to temporal lobe
Within what lobe or region of the cerebrum is the affective language area located in?
- opposite hemisphere from general interpretive center
What is meant by the term hemispheric (or cerebral) lateralization?
- 2 cerebral hemispheres (although they look the same) are slightly difft in structure and function
- each hemisphere tends to be involved w/sensory and motor functions of the opposite side of the body
What is meant by the term cerebral dominance?
- designates hemisphere that is dominant for language
- left cerebral hemisphere for language math and logic
- right for visual, spatial ,intuition, emotion
- if dominant is left, then you will be right handed (90% of people)
Which is the dominant hemisphere for most people?
Left hemisphere (90%) - so most people are right hnded
What are the major functions of the dominant hemisphere?
Left hemisphere - language, math logic
- dominance designates the side dominant for language
What are the major functions of the non-dominant hemisphere?
Right hemisphere - visual, spatial, intuition, emotion
- dominance designates the side dominant for language
Name and identify the function of the three different types of fiber tracts in the brain.
Commissures/commissural tracts (ex. the corpus callosum) - gonnect gyrea in the difft hemispheres; anterior and posterior commissure
Association fibers/tracts - connect b/w difft parts in SAME hemisphere; fibers can be short (arcuate fibers b/w adjacent gyrus) or long (fasciculi from one lobe to another)
Projection fibers/tracts (ex. internal capsule) - ascend/decend from cortex; connect cortex w/ brains stem, spinal cord, lower parts of brain
Internal capsule
- a projcection fiber/tract
- goes up through brainstem to primary motor cortex
- bass by basal nuclei creating gray and white striped look (why we call basal nuclei in 1 hemisphere the corpus striatum)
- past basal nuclei they fan out (coronal radiation)
What are the basal nuclei?
- gray matter, inferior to floor of lateral ventricles
- caudate nucleus, globus pallidus and putamen
control large automatic movemtns of skeletal muscles
- regulate intensity of movement and inhibit unwanted movements
What structures comprise the basal nuclei?
- Caudate nucleus
- Lentiform nucleus:
- globus pallidus and putamen
What are the general functions of the basal nuclei?
- control/regulate large automatic movements of skeletal muscles (like swinging your arms while you walk)
- regulate intensity of movement
- prevent unwanted movements
Amygdala
Nucleus sits on tail of caudate nucleus
Structurally associated with basal nuclei
Functionally associated with limbic system
What structures are included in the diencephalon?
- forms roof and walls of 3rd ventricle
- Thalamus
- Hypothalamus
- Epithalamus
Parkinson's disease
Degeneration of dopamine-releasing neurons of substantia niagra
Basal nuclei are deprived and become overactive
- tremors, slow in initiating and executing movement
What is the major function of the thalamus? Other functions?
- Main: relay of sensory information
- sensory input to cerebral cortex
- role in awareness, sensory integration, cognition, mood, motor function
What region of the diencephalon serves as a link between the nervous and endocrine systems?
The hypothalamus
- it regulates activity of the pituitary gland
What are the major functions of the hypothalamus?
- Control of the Autonomic nervous system (sympathetic and parasympathetic systems, HR, BP, contractility of heart, rate/depth of breathing, constriction of iris, contraction of urinary bladder.... )
- Control of endocrine system functioning (regulates pituitary gland)
- Center for emotional response (part of lymbic system, connectionj w/thalamus centers in brain stem)
- Body temp regulation
- Regulation of eating and drinking
- Regulation of sleep-wake cycles
Concussion
Alteration in brain function (usu. temporary), following a blow to head
Contusion
Bruising of the brain and permanent neurological damage
A more serious type of concussion (caused by a blow to the head)
Hydrocephalus
When circulation or drainage of CSF is obstructed
CSF accumulates and exerts pressure on brain
In baby, the head gets bigger, in adults, brain damage occurs
Treated by inserting a shunt into ventricles to drain fluid into abdominal cavity
What gland produces and secretes Melatonin? What is the function of this hormone?
- the epithalamus (specifically, the pineal gland which extends from the posterior border of the epithalamus)
- sleep/wake cycles; circadian rhythms
Where is the limbic system located?
- functional organization of structures
- medial aspect of cerebral hemispheres and diencephalons
- ring around top of brain stem
What structures make up the limbic system?
- cingulate gyrus, parahippocampal gyrus, dentate gyrus
- hippocampus and amygdala
- parts of several nuclei of thalamus and hypothalamus (parts of diencephalon)
- fornix and other tracts (how limbic system communicates)
What are the functions of the limbic system?
- affective/emotional brain
- links unconscious functions of brainstem (autonomic functions that regulate visceral functions) with conscious functions of cerebral cortex)
- consciously aware of emotional state
- memory storage and retrieval - hippocampus
- regulates/mediates response to stress
Identify the three major regions of the brain stem.
- midbrain
- pons
- medulla oblongata
What structures are located in the midbrain?
Cerebral aqueduct
Cerebral peduncles - large pyramidal motor tracts
Superior cerebellar peduncles - contain midbrain w/in cerebellum
Corpora quadrigemina - 4 reflex centers
R+L substantia nigra - makes dopamine from melanin
R+L red nuclei - high blood supply and iron; neurons from cerebral cortex and cerebellum synapse
Nuclei of 2 pairs of CNs:III and IV - ocular motor nerve and trochlear motor nerve
What is the function of the nuclei of the substantia nigra?
In midbrain
Contains melanin; precurser to dopamine; affect in basal nuclei
Die in parkinsons, so too little dopamine
What is the function of the nuclei of the corpora quadrigemina?
Two superior colliculi - reflex centers for movements of eyes, head and neck in response to primarily visual stimuli
Two interior colliculi - reflex centers for movements of head and trunk in response to auditory stimuli
What important structures are located in the pons?
Deeper longitudinal tracts - connect cerebrum and spinal cord
Middle cerebellar peduncles - connect pons with corresponding side of cerebellum
Nuclei of 4 paris of CN's
V - trigeminal n.; VI - abducins n.; VII facial n.; VIII - vestibulocochlear n.
Pneumotaxic and apneustic centers - respiratory
What is the function of the pneumotaxic and apneustic areas?
- Respiratory centers
- Work closely with respiratory centers in medula
- Rate/depth of breathing
What important structures are located in the medula oblongata? Identify the general function of each.
Pyramids - descending motor tracts; go from primary motor cortex to spinal cord; cross over at decussation of pyramids
Olives - inferior olivary nuclei relay sensory input from proprioceptors to cerebellum; joint position, amt of stress
Nucleus gracilis and nucleus cuneatus - relay station for sensory info to somatosensory cortex
Inferior cerebellar peduncles - tracts connect medulla and cerebellum
Nuclei of 5 pairs of CNs (VIII-XII)
Visceral motor nuclei
What happens in the decussation of the pyramids?
Crossover of fibers in pyramidal tract in medulla
Why brain controls motor functions contralaterally
Identify and describe the function of the main visceral motor nuclei of the medulla.
Cardiovascular center - HR, vasomotor function/constriction of blood vessels
Medullary respiratory centers
Other centers - involuntary motor functions - coughing, sneezing, hiccuping, swallowing, etc
What is the reticular formation?
- 3 columns
- part of brain stem
- sensory and motor function; input from cerebral cortex and hypothalamus, projects to multiple locations in cerebral cortex and spinal cord
Pain, visceral inputs, posture, muscle tone, reflex eye movements; cardiovascular and respiratory function
Where is the reticular formation located?
Extends through the central region of the brainstem
Collection of nuclei and the tracts b/w them
Neurons form 3 columns that extend the length of the brain stem
With what other structures (or regions) of the brain is the reticular formation connected?
Part of brain stem- medulla oblongata; pons; midbrain;
Involved in activating/arousing the cortex to a state of consciousness
Input from cerebral cortex and hypothalamus
Output to cerebral cortex and spinal cord
What is the function of the reticular activating system (RAS)?
- In reticular formation in brain stem
- arouse cortex to state of consciousness
- Communication b/w reticular formation and cerebral cortex
Filters out unnecessary stimuli; provides enough stimuli so cer. cortex stays alert
Coma
When the reticular activating system isn't working, so your cerebral cortex can't be aroused
No level of concsiousness
Describe the general structure of the cerebellum.
- Large mass of tissue on dorsal surface
- Below occipital lobes
- Posterior to pons and medulla
- separated from cerebrum by transverse fissure and tentorium cerbelli (dura mater)
- Lateral hemispheres connected by narrow vermis
- Fissures divide it into 3 lobes
Falx cerebelli separates and anchors the 2 hemispheres
Cortex has folia (gyri)
Has arbor vitae
Connected to brain stem by 3 cerebellar peduncles (superior, middle, inferior)
What are the functions of the cerebellum?
- Muscular activity, smooth motions, regulating posture and balance, muscle tone
- comparator function - compares intended movement with actual movement
- knowing current body position (unconscious level)
Ataxia
Cerebellar injury - results in marked loss of muscle tone and motor coordination/smoothness
- balance deterioration; similar effect to alcohol suppression of the same area
superior colliculus
- In midbrain - part of brain stem
- 2 of them
- reflex center for movements of eyes, head, neck in response to visual/other stimuli
Inferior colliculus
- In midbrain - part of brain stem
- 2 of them
- reflex center for movements of head and trunk in response to auditory stimuli
Decussation
Refers to the decussation of the pyramids
Crossover of the fibers in the pyramidal tract (in medulla, in brain stem)
Cerebellar Peduncles
3 - superior, middle, inferior
Carry sensory and motor impulses
Connect cerbellum to rest of brain
Arbor vitae
part of cerebellum
"tree of life"
White matter in the cerebellum resembles a tree