final exam Flashcards
What percent of neural tissue does the brain have?
97%
Be familiar with how the brain develops
This lateral view of the brain of an embryo after 4 weeks of development shows the neural tube, the hollow cylinder that is the beginning of the central nervous system. The internal passageway is called the neurocoel. In the cephalic portion of the neural tube, three areas enlarge rapidly through expansion of the internal cavity. This enlargement creates three prominent divisions called primary brain vesicles. The primary brain vesicles are named for their relative positions.
By week 5 of development, the primary brain vesicles have changed position and the prosencephalon and rhombencephalon have subdivided, forming secondary brain vesicles.
As development continues, the cerebrum enlarges to the point where it covers other portions of the brain
mesencephalon
or “midbrain,” is an expansion caudal to the prosencephalon.
prosencephalon
or “forebrain,” is at the tip of the neural tube.
rhombencephalon
or “hindbrain,” is the most caudal of the primary brain vesicles; it is continuous with the spinal cord
diencephalon
becomes the major relay and processing center for information headed to and from the cerebrum
telencephalon
begins to expand rapidly, eventually becoming the cerebrum, the largest part of the adult brain.
metencephalon
is adjacent to the mesencephalon. The region will form the cerebellum and the pons of the adult brain.
myelencephalon
will become the medulla oblongata
cerebrum
is divided into a pair of large cerebral hemispheres. the surfaces of the cerebral hemispheres are highly folded and covered by a superficial layer of gray matter called the cerebral cortex. Functions include conscious thought, memory storage and processing, sensory processing, and the regulation of skeletal muscle contractions.
Fissures (cerebrum)
deep grooves that subdivide the cerebral hemisphere.
Gyri (cerebrum)
folds in the cerebral cortex that increase its surface area
Sulci (cerebrum)
shallow depressions in the cerebral cortex that separate adjacent gyri
diencephalon
the structural and functional link between the cerebral hemispheres and the rest of the CNS
thalamus (diencephalon)
contains relay and processing centers for sensory information.
hypothalamus (diencephalon)
or floor of the dicencephalon, contains centers involved with emotions, autonomic function, and hormone production.
Brain stem
includes the midbrain, pons, and medulla oblongata
midbrain (brain stem)
contains nuclei that process visual and auditory information and control reflexes triggered by these stimuli. It also contains centers that help maintain consciousness
pons (brain stem)
connects the cerebellum to the brain stem. In addition to tracts and relay centers, the pons also contains nuclei that function in somatic and visceral motor control.
medulla oblongata
relays sensory information to other portions of the brain stem and to the thalamus. The medulla oblongata also contains major centers that regulate autonomic function, such as heart rate and blood pressure.
Ventricles
During development, the neurocoel within the cerebral hemispheres, diencephalon, metencephalon, and medulla oblongata expands to form chambers called ventricles
The ventricles are filled with CSF and lined by ependymal cells.
Ventricles of the brain (lateral ventricle)
Each cerebral hemisphere contains a lateral ventricle
Ventricles of the brain (interventricular foramen)
Each lateral ventricle communicates with the third ventricle through an interventricular foramen
Ventricles of the brain (third ventricle)
The third ventricle is located in the diencephalon
Ventricles of the brain (aqueduct of the midbrain)
the aqueduct of the midbrain is a slender canal within the midbrain that connects the third ventricle to the fourth ventricle.
Ventricles of the brain (fourth ventricle)
The fourth ventricle begins in the metencephalon and extends into the superior portion of the medulla oblongata. It then narrows and becomes the central canal of the spinal cord
How many ventricles are there in the brain?
4
corpus callosum
a thick tract of white matter that interconnects the two cerebral hemispheres
septum pellucidum
a partition that separates the two lateral ventricles.
cranial meninges
The delicate tissues of the brain are protected by mechanical forces with the help of these
[1] Dura Mater (cranial meninges)
The cranial dura mater consists of outer and inner fibrous layers. The outer layer is fused to the periosteum of the cranial bones. As a result there is no epidural space. The outer (endosteal) and inner (meningeal) layers of the cranial dura mater are typically separated by a slender gap that contains tissue fluids and blood vessels, including several large dural sinuses, which collect blood from the veins of the brain.
Dural mater (endosteal layer) Dural sinus Dural mater (meningeal layer)
[2] Arachnoid mater (cranial meninges)
The cranial arachnoid mater consists of the arachnoid membrane and the arachnoid trabeculae (which connect to the pia mater). The arachnoid membrane provides a smooth covering that does not follow the brain’s underlying folds. The subarachnoid space lies between the arachnoid membrane and the pia mater.
Arachnoid membrane
Subarachnoid space
Arachnoid trabeculae
[3] Pia mater (cranial meninges)
Astrocyte processes bind the pia mater to the surface of the brain. The pia mater sticks to the surface of the brain. It extends into every fold and accompanies the branches of cerebral blood vessels as they penetrate the surface of the brain to reach internal structures.
dural folds
sheets that dip inward and then return. These provide additional stabilization and support to the brain
Dural sinuses
large collecting veins located within the dural folds (there are 3 large dural folds)
falx cerebri
a fold of dura mater that projects between the cerebral hemispheres. Its inferior portions attach anteriorly to the crista galli and posteriorly to the internal occipital crest of the occipital bone. The superior and inferior sagittal sinuses lie within this dural fold.
superior sagittal sinus
the largest dural sinus
tentorium cerebelli
separates the cerebral hemispheres from the cerebellum.
falx cerebelli
separates the two cerebellar hemispheres along the midsagittal line inferior to the tentorium cerebelli
cerebrospinal fluid (CSF)
completely surrounds and bathes the exposed surfaces of the CNS.
The CSF circulates from the choroid plexuses through the ventricles and fills the central canal of the spinal cord. As it circulates, materials diffuse between the CSF and the interstitial fluid of the CNS across the ependymal cells.
Choroid plexuses
Each of the ventricles contains an area of choroid plexus, which consists of a combination of specialized ependymal cells and capillaries involved in the production of and maintenance of CSF.
medulla oblongata
all communication between the brain and spinal cord involves tracts that ascend or descend through the medulla oblongata is a center for the coordination of relatively complex autonomic reflexes and the control of visceral functions.
tracts (medulla oblongata)
Descending tracts cover the anterior surface of the medulla oblongata
Olive (medulla oblongata)
the olive is a prominent olive-shaped bulge along the anterolateral surface of the medulla oblongata. It follows the contours of the olivary nucleus.
pyramids (medulla oblongata)
the pyramids contain tracts of motor fibers that originate at the cerebral cortex.
some of the pyramidal fibers cross over to the opposite side of the medulla as they descend into the spinal cord. That crossing is called a decussation.
autonomic centers (medulla oblongata)
control vital functions
relay stations (medulla oblongata)
located along sensory and motor pathways
(medulla oblongata gray matter component & function)- Nucleus gracilis, nucleus cuneatus
relay somatic sensory information to the thalamus
(medulla oblongata gray matter component & function)- Olivary nuclei
Located within the olives; relay information from the red nucleus, other nuclei of the midbrain, and the cerebral cortex to the cerebellum
(medulla oblongata gray matter component & function)- Solitary nucleus
integrates and relays visceral sensory information to autonomic processing centers
Autonomic reflex center-(medulla oblongata gray matter component & function)- Cardiac Centers
regulate heart rate and force of contraction
Autonomic reflex center-(medulla oblongata gray matter component & function)- Vasomotor Centers
regulate distribution of blood flow
Autonomic reflex center-(medulla oblongata gray matter component & function)- Respiratory Rhythmicity Centers
Set the pace of respiratory movements
Other nuclei/centers-(medulla oblongata gray matter component & function)
Contain sensory and motor nuclei of cranial nerves VIII (in part), IX, X, XI (in part), and XII; relay ascending sensory inforamtion from the spinal cord to higher centers
(medulla oblongata white matter component and function0- Ascending and Descending Tracts
Link the brain with the spinal cord
pons
the pons link the cerebellum with the midbrain, diencephalon, cerebrum, medulla oblongata, and spinal cord.
reticular formation (pons)
a loosely organized mass of gray matter that contains embedded nuclei and centers that regulate vital autonomic functions. It extends from the medulla oblongata to the mesencephalon.
(pons and gray matter component and function)- Nuclei Associated With Cranial Nerves V,VI,VII, and VIII (in part)
relay sensory information and issue somatic motor commands
(pons and gray matter component and function)- Apneustic and Pneumotaxic Centers
adjust activities of the respiratory rhythmicity centers in the medulla oblongata
(pons and gray matter component and function)- Relay Centers
relay sensory and motor information to the cerebellum
(pons and white matter component and function)- Ascending Tracts
carry sensory information from the nucleus cuneatus and nucleus gracilis to the thalamus
(pons and white matter component and function)- Descending Tracts
carry motor commands from higher centers to motor nuclei of cranial or spinal nerves
(pons and white matter component and function)- Transverse Fibers
interconnect processing centers in the cerebellar hemispheres
cerebellum
an automatic processing center that monitors proprioceptive, visual, tactile, balance, and auditory sensations.
It has 2 primary functions:
1) Adjusting the postural muscles of the body
2) Programming and fine-tuning movements controlled at the conscious and subconscious levels.
vermis (cerebellum)
the vermis is a narrow band of cortex that separates the cerebellar hemispheres
primary fissure (cerebellum)
the anterior and posterior lobes are separated by the primary fissure
cerebellum lobes
the cerebellum has 2 large anterior and posterior lobes. Like the cerebrum, the cerebellum has 2 hemispheres and the surface is covered with a layer of gray matter-the cerebellar cortex
folia (cerebellum)
the folia are folds of the cerebellar surface. They are less prominent than the folds in the surfaces of the cerebral hemispheres
purkinje cells
a large, branching neuron of the cerebellar cortex
cerebellar peduncles
tracts that link the cerebellum with the brain stem, cerebrum, and spinal cord form 3 cerebellar peduncles on each side
superior cerebellar peduncle
middle cerebellar peduncle
inferior cerebellar peduncle
arbor vitae (cerebellum)
the white matter of the cerebellum forms a branching array that in sectional view resembles a tree. Anatomists call it the arbor vitae, or “tree of life.”
(cerebellum gray matter component and function)- Cerebellar Cortex & Cerebellar Nuclei
involuntary coordination and control of ongoing body movements
(cerebellum white matter component and function)- Arbor Vitae
connects cerebellar cortex and nuclei with cerebellar peduncles
(cerebellum white matter component and function)- Cerebellar Peduncles
Superior=Link the cerebellum with midbrain, diencephalon, and cerebrum
Middle=Contain transverse fibers and carry communications between the cerebellum and pons
Inferior= Link the cerebellum with the medulla oblongata and spinal cord
(cerebellum white matter component and function)- Transverse Fibers
interconnect pontine nuclei with the cerebellar hemisphere on the opposite side
ataxia
a disturbance in muscular coordination. In severe ataxia, the individual cannot sit or stand without assistance.
Midbrain (main section)
the most complex and integrative portion of the brain stem
corpora quadrigemina
are two pairs of sensory nuclei located in the roof of the midbrain
superior colliculus (corpora quadrigemina-midbrain)
recieves visual inputs from the thalamus and controls the reflex movements of the eyes, head, and neck in response to these visual stimuli
inferior colliculus (corpora quadrigemina-midbrain)
receives auditory data from nuclei in the medulla oblongata and pons and controls reflex movements of the head, neck and trunk in response to these auditory stimuli.
Reticular activating system [RAS] (midbrain)
is a specialized part of the reticular formation. Stimulation of the RAS produces unconsciousness.
red nucleus (midbrain)
the red nucleus receives information from the cerebrum and cerebellum and issues subconscious motor commands that affect upper limb position and background muscle tone.
substantia nigra (midbrain)
contains darkly pigmented cells that adjust activity in the basal nuclei of the cerebrum.
tectum (midbrain)
the tectum, or roof of the midbrain, is the region posterior to the aqueduct of the midbrain.
(midbrain gray matter component and function)- Superior Colliculi
integrate visual information with other sensory inputs; intiate reflex responses to visual stimuli
(midbrain gray matter component and function)- Inferior Colliculi
relay auditory information to medial geniculate nuclei; initiate reflex responses to auditory stimuli
(midbrain gray matter component and function-walls and floor)- Red Nuclei
provide subconscious control of upper limb position and background muscle tone.
(midbrain gray matter component and function-walls and floor)- Substantia Nigra
regulates activity in the basal nuclei
(midbrain gray matter component and function-walls and floor)- Reticular Formation [headquarters]
processes incoming sensations and outgoing motor commands automatically; can initiate involuntary motor responses to stimuli; helps maintain consciousness
(midbrain gray matter component and function)- Other Nuclei/Centers
are associated with cranial nerves III and IV
(midbrain white matter component and function)- Cerebral Peduncles
connect primary motor cortex with motor neurons in brain and spinal cord; carry ascending sensory information to thalamus.
Diencephalon consists of […] (main section pg.438)
consists of the epithalamus, thalamus (left and right), and hypothalamus
epithalamus (diencephalon)
the roof of the diencephalon superior to the third ventricle. The anterior portion of the epithalamus contains an extensive area of choroid plexus that extends through the interventricular foramina.
anterior commissure (diencephalon-epithalamus)
a tract that interconnects the cerebral hemispheres and the optic chiasm
optic chiasm (diencephalon-epithalamus)
where the optic nerves attach to the brain
Thalamus (diencephalon)
On each side of the brain, a thalamus sits superior to the midbrain.
interthalamic (diencephalon-epithalamus)
a projection of gray matter called an interthalamic adhesion extends into the ventricle from the thalamus on either side, although no fibers cross the midline
pineal gland (diencephalon-epithalamus)
the pineal gland lies in the posterior, inferior portion of the epithalamus. It is an endocrine structure that secretes the hormorne melatonin.
Melatonin (diencephalon-epithalamus-pineal gland)
Melatonin is important in the regulation of day-night cycles and also in the regulation of reproductive functions.
lateral geniculate nucleus (diencephalon-thalamus)
the lateral geniculate nucleus of each thalamus receives visual information over the optic tract and sends signals to both the midbrain and occipital lobe of the cerebral hemisphere on that side.
Optic tract (diencephalon-thalamus)
the tract over which nerve impulses from the retina are transmitted between the optic chiasm and the thalamus.
medial geniculate nucleus (diencephalon-thalamus)
the medial geniculate nucleus of each thalamus relays auditory information from specialized receptors of the inner ear to the appropriate area of the cerebral cortex.
Anterior group-thalamus
Part of the limbic system
Medial group-thalamus
integrates sensory information for projection to the frontal lobes of the cerebral hemispheres
