Term 3 Chapter 18 Brain Flashcards
What is the brain in terms of nervous system?
The brain is the portion of the CNS that is contained within the cranium (cranial cavity)
What are the four major regions of the brain?
- Brainstem
- Cerebellum
- Diencephalon
- Cerebrum
What are three parts of the Brainstem?
- Midbrain
- Pons
- Medulla oblongata
What are three parts of the Diencephalon?
- Epithalamus (includes pineal gland)
- Thalamus
- Hypothalamus
The cerebrum is split into a right and left _______, each half has ____ lobes?
hemisphere, Five
What four structures play a role in support and protection of the brain?
- Cranium (skull)
- Cranial Meninges
- Cerebrospinal Fluid (CSF)
- Blood-Brain barrier
How does cerebrospinal fluid protect and support the brain?
CSF is clear, colourless fluid that protects the brain and spinal cord against chemical and physical injury
The cranial meninges are _______ with the spinal meninges: Outer ________, Middle________, and Innermost _________
The cranial meninges are continuous with the spinal meninges: Outer dura mater, Middle arachnoid mater, and Innermost pia mater
How does the cranial dura mater compare to the spinal dura mater?
The cranial dura mater has 2 layers while the spinal dura mater has only one
Between the spinal dura mater and the vertebral wall, there is an epidural space. Where is the epidural space around the brain?
There is NO epidural space around the brain
The two cranial dura mater layers around the brain are fused together and separate to enclose the __________
The two cranial dura mater layers around the brain are fused together and separate to enclose the dural venous sinuses
What are the dural venous sinuses?
Endothelial lined venous channels that drain venous blood from the brain and deliver it into the internal jugular veins
The dura mater form 3 extensions that separate parts of the brain. What are these extensions and what do they separate?
- Falx cerebri: separates the two hemispheres of the cerebrum
- Falx cerebelli: separates the two hemispheres of the cerebellum
- Tentorium cerebelli: separates the cerebrum from the cerebellum
What are the three main functions of the cerebrospinal fluid (CSF)?
- Mechanical protection: absorbs shock
- Chemical protection: CSF provides optimal chemical environment for neuronal signalling
- Circulation: medium for minor exchange in nutrients and oxygen and waste products between blood and nervous tissue
Where does the majority of CSF production occur?
In the choroid plexuses (capillary networks) in the walls of ventricles
How many CSF-filled ventricles can be found in the brain? What is their purpose?
4
Serve as a reservoir of CSF secreted from adjacent choroid plexuses
What are the four csf-filled ventricles in the brain called?
- 2x lateral ventricles (one in each hemisphere of the cerebrum)
- Third ventricle
- Fourth ventricle
The two lateral ventricles are separated by the_______
the septum pelucidum
Which ventricle lies between the brainstem and cerebellum
the fourth ventricle
Which ventricle is a narrow cavity along midline superior to the hypothalamus, and between the right and left halves of the thalamus
The third ventricle
CSF Circulation:
- CSF formed in the choroid plexuses of each lateral ventricle flows into the third ventricle through the ___________\_
- More CSF added in the ________
- CSF then flows to the _______ via the ______ of the midbrain (______) - passes through the midbrain
- Small amounts of CSF travel downward through the _______ of the spinal cord
- Majority of CSF enters the ________ via the 3 openings (______, or paired ______) in the _________
- CSF formed in the choroid plexuses of each lateral ventricle flows into the third ventricle through the Interventricular foramina
- More CSF added in the third ventricle
- CSF then flows to the fourth ventricle via the aqueduct of the midbrain ( cerebral aqueduct) - passes through the midbrain
- Small amounts of CSF travel downward through the central canal of the spinal cord
- Majority of CSF enters the subarachnoid space via the 3 openings ( Median aperture , or paired lateral apertures ) in the fourth ventricle
CSF circulation continued:
- CSF then circulates through the ________ around the surface of the brain and spinal cord
- CSF is gradually reabsorbed into the blood through _________
- CSF then circulates through the Subarachnoid space around the surface of the brain and spinal cord
- CSF is gradually reabsorbed into the blood through arachnoid villi
What are arachnoid villi?
Fingerlike extensions of the arachnoid that project into the dural venous sinuses, especially the superior sagittal sinus
Label the summary of the formation, circulation and absorption of CSF
Label the sagittal section of the brain
What is the function blood-brain barrier?
Protects brain from harmful substances and pathogens
- very selective of what can cross
- Proteins and antibiotics cannot cross
- small compounds (ie oxygen, carbon dioxide, anaesthetic drugs and alcohol) can cross
What does the blood brain barrier consist of?
What is the purpose of astrocytes in the BBB?
Tight junctions between endothelial cells of brain capillaries
- Thick basement membrane surrounds the capillaries
- Astrocytes help maintain the strength of tight junctions
The Brainstem is part of the brain between the _____ and the ______ and consists of three structures:
The Brainstem is part of the brain between the spinal cord and the diencephalon and consists of three structures:
- Midbrain
- Pons
- Medulla oblongata
What is the Reticular formation?
net-like region of interspersed grey and white matter that extends throughout the brainstem
The ________ is a continuation of the superior part of the spinal cord\
Medulla oblongata
The medulla oblongata begins at the _______ and extends to the inferior border of the _____ to form the ______ part of the brainstem
The medulla oblongata begins at the foramen magnum and extends to the inferior border of the pons to form the inferior part of the brainstem
The medulla oblongata contains nuclei that control vital functions; what are these nuclei?
Masses of grey matter where neurons synapse with other neurons
The medulla oblongata has four “centers” that control various functions. What are they?
- Cardiac centre: controls rate of heartbeat
- Vasomotor centre: controls blood pressure by causing arteriole constriction
- Respiratory centre: controls the rate and depth of breathing
- Centres of reflex: eg sneezing, coughing, swallowing etc
What are pyramids in the medulla oblongata?
White matter that bulges on the anterior aspects of the medulla
What is decussation of the pyramidal olive?
crossing of axons of the spinal cord from right to left and vice versa
What does the inferior olivary nucleus (in medulla oblongata) do
Relay impulses from proprioceptors to cerebellum
What are the gracile and cutaneous nuclei (medulla oblongata)
How do signals travel here?
Associated with touch, pressure, vibrations and proprioception
Signal travels in axons through the medial lemniscus to the thalamus
What five pairs of cranial nerves have nuclei of origin in the medulla oblongata?
- Vestibulocochlear (VIII) nerves - hearing
- Glossopharyngeal (IX) nerves - taste, swallowing and salivation
- Vagus (X) nerves - mixed (sensory and motor) nerve that is widely distributed from the head, neck into the thorax and abdomen
- Accessory (XI) nerves - cranial portion include the first five segments of the cervical spinal cord to coordinate head movements
- Hypoglossal (XII) nerves - control the tongue relating to speech and swallowing
The pons consists of ______(____) and _____ and forms a _____ that connects parts of the brian with one another
The pons consists of nuclei (pontine nuclei) and tracts and forms a bridge that connects parts of the brain with one another; connect the right and left sides of the cerebellum
the pons links the cerebellum with the ______, _______, _____, ______, and ______
the pons links the cerebellum with the midbrain, diencephalon, cerebrum, medulla oblongata, and spinal cord
Label:
The pons contains nuclei associated with which four pairs of cranial nerves? What are each of these nerves in charge of?
- Trigeminal (V) nerves - receive sensory impulses from the head and face and provide motor impulses that control chewing
- Abducens (VI) nerves - motor control of eyeball movements
- Facial (VII) nerves - receive sensory impulses for taste, provide motor impulses that control salivation, tears, and facial expressions
- Vestibulocochlear (VIII) nerves - nerves of the vestibular apparatus of the inner ear relating to balance and equilibrium
The midbrain (aka mesencephalon) extends from the ____ to the _____
The midbrain extends from the pons to the diencephalon
The ______ passes through the midbrain connecting the ____ ventricle above to the _____ ventricle below
The Cerebral aqueduct passes through the midbrain connecting the third ventricle above to the fourth ventricle below
The anterior part of the midbrain contains a pair of tracts called________
Cerebral peduncles
The posterior part of the midbrain is called the _______, and has two features:
tectum
- Superior colliculi
- Inferior colliculi
What are the superior colliculi (midbrain)
two superior elevations of the midbrain
- nuclei that serves as the centers for certain visual activities eg tracking eye movements/ movements of head and neck
What are the inferior colliculi?
Inferior elevations
Part of the auditory reflex
Relays impulse from the receptors for hearing in the ear to the thalamus
What is the substantia nigra? What does it release? What is the result of damage to its neurons?
Dark pigmented nuclei
- neurons release dopamine and help control subconcious muscle activities
- Loss of neurons = parkinsons
What do red nuclei appear red?
What is the function of red nuclie?
- Looks red because of rich blood supply
- Function with cerebellum to coordinate muscular movement
What is the mesencephalic nucleus?
The ONLY nucleus in the CNS that is not a synaptic relay station between neurons
-Contains sensory cell bodies of proprioceptive neurons: spatial sense of body parts relative to one another
Which is the only nucleus in the central nervous system that isn’t a synaptic relay centre between neurons?
the Mesencephalic nucleus in the midbrain
Nuclei in the midbrain are associated with which two cranial nerves?
What are these nerves involved in?
- Oculomotor (III) nerves:
- Provide motor impulses that control movement of eyeballs
- Accessory occulomotor nuclei provide motor control of the smooth muscles that regulate constriction of the pupil and shape of lens
- Trochlear (IV) nerves:
- Provide motor impulses that control movements of eyeball
What is the reticular formation? What does it contain?
In the midbrain:
- broad region of netlike arrangement of white and grey matter
- Contains both ascending (sensory) and descending (motor) neurons
What part of the midbrain extends from the superior part of the spinal cord, throughout the brainstem, and into the inferior part of the diencephalon?
The Reticular Formation
What is the Reticular Activating System (RAS)?
What does it function in?
- Projections of sensory axons from the reticular formation into the cerebral cortex
- Helps Maintain Consciousness - Active during awakening from sleep; maintain attention and alertness
The reticular formation’s main descending function is to _________; to help maintain ______
The reticular formation’s main descending function is to help regulate muscle tone; to help maintain posture
The ______ is the second largest part of the brain
Cerebellum
The central constricted area of the cerebellum is called the?
The vermis
What does the flocculonodular lobe of the cerebellum contribute to?
equilibrium and balance
The anterior and posterior lobes of the cerebellum govern _______ ?
The anterior and posterior lobes of the cerebellum govern subconscious aspects of the skeletal muscle activities
eg catching a ball
What does the cerebellar cortex consist of
grey matter in a series of slender parallel ridges called folia
What are arbor vitae (cerebellum)?
Tracts of white matter
Located within white matter of the cerebellum are the _________ which are the origin of axons that carry impulses from the cerebellum to other brain centers and to the spinal cord
Located within white matter of the cerebellum are the cerebellar nuclei which are the origin of axons that carry impulses from the cerebellum to other brain centers and to the spinal cord
Cerebellar ______ are bundles of white matter consisting of axons that conduct impulse between the cerebellum and other parts of the brain that attach the cerebellum to the brainstem
Peduncles
What part of the brain is illustrated: forms a central core of brain tissue just superior to the midbrain
Diencephalon
The diencephalon contains numerous _____ involved in _____ and ______ processing between higher and lower brain centres
The diencephalon contains numerous nuclei involved in sensory and motor processing between higher and lower brain centres
What three structures are a part of the diencephalon?
- thalamus
- hypothalamus
- epithalamus
Projecting from the hypothalamus is the _______
pituitary gland
The _____ transmits information from the cerebellum and basal ganglia to the primary motor area of the cerebral cortex
Thalamus
The thalamus is a “major relay station” for ?
Most sensory impulses from the spinal cord, brainstem, and midbrain that reach the primary sensory areas of the cerebral cortex
What are the seven major groups of nuclei on each side of the thalamus?
- Anterior nucleus
- Medial nuclei
- Lateral group
- Ventral group
- Intralaminar nuclei
- midline nucleus
- Reticular nucleus
The anterior nucleus of the thalamus connects the _____ and _______
The anterior nucleus of the thalamus connects the hypothalamus and limbic system
The medial nuclei of the thalamus connect to the _______, _______, and ______
The medial nuclei of the thalamus connect to the cerebral cortex, limbic system, and basal ganglia
Which group of nuclei of the thalamus connect to superior colliculi, limbic system and cortex in all lobes of the cerebellum?
The Lateral group
The ventral group of nuclei in the thalamus consists of five different nuclei:
- ventral anterior nucleus
- ventral lateral nucleus
- ventral posterior nucleus
- Lateral geniculate nucleus
- Medial geniculate nucleus
The intralaminar nuclei lie within the ______ and makes connections with the ______, ______, ______ and wide areas of the _____
The intralaminar nuclei lie within the internal medullary lamina and makes connections with the reticular formation, cerebellum, basal ganglia, and wide areas of the cerebral cortex
The ______ nucleus of the thalamus forms a thin band adjacent to the third ventricle and is presumed to function in memory and olfaction
Midline
The _____ nucleus of the thalamus surrounds the lateral aspect of the thalamus and monitors, filters and integrates activities of other thalamic nuclei
Reticular nucleus
The hypothalamus is composed of a dozen or so nuclei in four major regions, name the regions
- Mammillary region
- Tuberal region
- Supraoptic region
- Preoptic region
The mammillary region of the hypothalamus serves as a relay station for reflexes related to the _________
Sense of smell
The tuberal region of the hypothalamus is the widest part of the hypothalamus and includes three nuclei: _______, ________ and _______ as well as a stalk like _______ which connects the pituitary gland to the hypothalamus
The tuberal region of the hypothalamus is the widest part of the hypothalamus and includes three nuclei: dorsomedial, ventromedial, and arcuate nuclei as well as a stalk-like infundibulum which connects the pituitary gland to the hypothalamus
Which region of the Hypothalamus lies superior to the optic chiasm?
Which four nuclei can be found in this region?
Supraoptic region
- paraventricular nucleus
- supraoptic nucleus
- anterior hypothalamic nucleus
- suprachiasmatic nucleus
The preoptic region of the hypothalamus contains the _____ and _____ _____ _____ and functions in the regulation of?
The preoptic region of the hypothalamus contains the medial and lateral preoptic nuclei and functions in the regulation of certain autonomic activities: thirst, and implied parental and sexual behaviours
The hypothalamus controls many body activities:
- Major regulator of _______ (temperature, water/electrolyte balance) by controlling and integrating the activities of the ______
- Produces ______
- Acts as a _________
- Regulation of:
- ________
- Emotional and behavioural patterns (ie sexual response; aggression; pleasure etc)
The hypothalamus controls many body activities:
- Major regulator of homeostasis (temperature, water/electrolyte balance) by controlling and integrating the activities of the autonomic nervous system (ans)
- Produces hormones
- Acts as a cardiovascular centre
- Regulation of:
- sleeping/wakefulness (circadian rhythm)
- Emotional and behavioural patterns (ie sexual response; aggression; pleasure etc)
Posterior to the thalamus is the ______
epithalamus
The epithalamus consists of the _____ gland and the ______ nuclei
The epithalamus consists of the pineal gland and the habenular nuclei
Habenular nuclei (of epithalamus) are involved in _______
olfaction
In particular: emotional responses to odors
The pineal gland protrudes from the posterior midline of the ________ and is a part of the endocrine system that secretes the hormone _______
The pineal gland protrudes from the posterior midline of the third ventricle and is a part of the endocrine system that secretes the hormone melatonin
What are the circumventricular organs? What do they do?
Parts of the diencephalon that lie in the wall of the third ventricle and monitor chemical changes in the blood
Name three structures that are a part of the Circumbentricular Organs:
- Part of the hypothalamus
- Pineal gland
- pituitary gland
Why is the circumventricular organs a site of HIV entrance to the brain?
It lacks a blood brain barrier
Functionally, the regions of the Circumventricular organs (pineal gland, hypothalamus, and pituitary gland) coordinate ________ activities of the ______ and _____ systems.
Functionally, the regions of the Circumventricular organs (pineal gland, hypothalamus, and pituitary gland) coordinate homeostatic activities of the endocrine and nervous systems
The cerebrum is considered the site of ?
intelligence
What is the largest part of the human brain?
The cerebrum
The cerebrum consists of the ______ and the _______
The cerebrum consists of the cerebral hemispheres and the basal ganglia
What separates the left and right halves of the cerebrum?
The falx cerebri
Each hemisphere contains:
- An outer rim of grey matter: the ______
- An internal region of ______
- _______ nuclei deep within the white matter
Each hemisphere contains:
- An outer rim of grey matter: the cerebral cortex
- An internal region of white matter
- Grey matter nuclei deep within the white matter
What are the folds of the cerebrum called?
gyri or convolutions
Deep grooves between the folds of the cerebrum are called?
fissures
Shallow grooves between the folds of the cerebrum are ?
sulci
What are the four cerebral lobes?
Frontal
Parietal
Temporal
Occipital
The ______ separates the frontal lobe from the parietal lobe
Central sulcus
Located immediately anterior to the central sulcus is the _______ which contains the primary motor area
Located immediately anterior to the central sulcus is the precentral gyrus which contains the primary motor area
The _______ separates the frontal lobe from the temporal lobe
Lateral cerebral sulcus
The ______\_ separates the parietal lobe from the occipital lobe
The parieto-occipital sulcus separates the parietal lobe from the occipital lobe
What are the three primary types of myelinated axons in the cerebral white matter?
- Association tracts
- commissural tracts
- Projection tracts
Which tracts in the cerebral white matter conduct nerve impulses between gyri in the same hemisphere?
Association tracts
What are the motor areas of the cerebrum?
- Primary motor area
- Motor speech area (broca’s area)
what are the five sensory areas of the cerebrum?
- Primary somatosensory area
- Primary visual area
- Primary auditory area
- Primary gustatory area
- Primary olfactory area
What are the five association areas of the cerebrum?
- Somatosensory association area
- Visual association area
- Auditory association area
- Wernicke’s area
- Gnostic area
The limbic system’s primary role is in?
range of emotion
- Including pain, pleasure, docility, affection, anger etc
- Involved in social and sexual behaviours as well as memory
What are the basal nuclei?
collection of three nuclei located deep within each cerebral hemisphere
What do the basal nuclei do?
Control automatic movements of skeletal muscles and muscle tone - regulate initiation and termination of movements
Activity of neurons in the ______ precedes (anticipates) body movements
putamen
Activity of neurons of _______ precedes eye movement
Caudate nucleus
______ (of basal nuclei) helps regulate muscle tone for specific body movements?
Globus pallidus
