1_Intro to Nervous System Flashcards
What are 2 levels of analysis?
Segmental vs. suprasegmental Segmental= (a cross-sectional component of the brainstem or spinal cord containing neural inputs and outputs. ) suprasegmental= (spinal, medullary, midbrain, and cortical)
What is the emergent property
consciousness (an example b/c the act of thinking, emerges from the unified actions of various parts of the brain. *the structure and function of lower levels of the system cannot explain the function and structure of higher levels)
What is distributed control?
coordination of differing activities
Redundant representations are __________________?
Different sensory modalities used to describe one object (i.e. an orange)
What are parallel and serial processes?
Multiple levels of analysis vs. ascending information. Serial processing: info traveling up or down through the levels of the system. Parallel processing: different inputs (thing of orange example) processed by different sensory systems, but messages about them may be received by the brain simultaneously along different parallel pathways.
What are two types of feedback?
positive and negative (various pathways connect one nerve cell to the next cells but also to previous nerve cells, giving a cell the opportunity to affect the activity of an earlier cell in the pathway.)
What type of processing is integration?
parallel processing
What is considered adaptation?
learning, re-learning, development processes, plasticity
What is columnar organization?
development aspect of motor vs sensory [“many parts of the nervous system are organized in vertical columns, particularly the older areas. Ex: groups of cells involved in taste form a long column in the base of the brain. Also, in the base of the brain, the group of cells that control eye movements are located one above the other, in a broken column (discontinuous)”]
How are convergence and divergence used?
Used in integration and refinement of stimuli.
Afferent designates _____ connections. Efferent designates _____ connections.
incoming outgoing
“In this sense, a central nervous system neuron can be ____ afferent and/or efferent
BOTH
The spinal cord and brain develop from what?
Neural tube
The majority of the Peripheral Nervous System (PNS) develops from the (1)______ ____. And includes the (2)______ _____ _____ that are the cell bodies for all of the sensory side of the (3)______ _______ ______, (4) ______ _____, and the (5)________ of the autonomic nervous system.
- neural crest 2. dorsal root ganglia 3. Peripheral nervous system 4. Schwann cells 5. ganglia
Schwann cells are myelinating cells of the peripheral nervous system, BOTH sensory and motor, true or false?
True
What additional structures (beyond the PNS) are neural crest cells responsible for generating?
Melanocytes in stratum basale of the epidermis.
What 4 plates is the developing neural tube divided into?
- roof 2. floor 3. alar 4. basal
The alar plate is located ____ to sulcus limitans and forms the _____ and _______ association part of the developing neural tube.
dorsal sensory association
The basal plate lies _____ to the sulcus limitans and forms the _____ part of the developing neural tube, including both _____ and _____ motor neurons
anterior motor alpha gamma
Do the roof and floor plates generate neuronal components?
NO (none to speak of)
What is the name of the groove (oriented in the coronal plane) that separates the wall of the neural tube?
sulcus limitans
How far is this dividing line present in the developing cord and into the brainstem?
Only as far as the developing MINDBRAIN.
The developing neural tube expands at the _____ end into three primary vesicles: ____________, _______________, and ____________.
rostral rhombencephalon MESencephalon prosencephalon
The rhombencephalon expands to secondary vesicles ______ and ______.
MYelenchephalon METencephalon
The prosencephalon expands to second vesicles ______ and ______.
DIEncephalon TELencephalon
The MYelencephalon includes the _____?
medulla
The METencephalon includes the _____?
pons and cerebellum
The MESencephalon includes the _____?
midbrain
The diencephalon includes the _____?
thalamus and hypothalamus
The telencephalon includes the _____?
cerebral hemispheres and basal ganglia
What does the development and expansion of the secondary brain vesicles result in?
The formation of the brain and brainstem.
What does the spinal cord form from?
The remainder of the neural tube
What expands with the developing vesicles to form the ventricular system?
Lumen of the neural tube
The lumen of the neural tube is also continuous with the __________________________, a remnant of the neural tube.
central canal of the spinal canal.
At what embryological level are the two lateral ventricles located?
Telencephalon
A third unpaired ventricle is located in the ___________.
Diencephalon
The fourth ventricle is located in the ________ and ________ below the _________.
pons and medulla below the cerebellum.
What does the longitudinal fissure divide?
cerebral hemispheres.
What does the transverse fissure divide?
Separates the cerebrum from the cerebellum.
The frontal and parietal lobes are divided by the __________________.
central sulcus
The central sulcus is also the landmark separating the _______________________________________.
pre and poscentral gyri primary motor and sensory cortices
The paracentral lobule is the ________________________.
midline extension of the pre and postcentral gyri
Which sulcus divides the temporal lobe from the frontal and parietal lobes?
Lateral sulcus
An “imaginary” line between which to areas separates the occipital lobe from the parietal and temporal lobes.
parieto-occipital notch and preoccipital notch
The calcarine sulcus marks which area?
The primary visual cortex; separating the cuneus and lingual gyri
Which two lobes does the parieto-occipital sulcus seperate?
Midline part of the occipital lobe from the parietal lobe.
The cingulate sulcus is also know as a
midline sulcus
List 11 structures that are best seen on a midsagittal view of the brain:
1) corpus callosum 2) fornix 3) anterior commisure 4) lamina terminalis 5) interventricular foramen 6) thalamus 7) hypothalamus 8) midbrain or mesencephalon 9) pons 10) medulla 11) cerebellum
What does the lamina terminalis mark?
the closure of the anterior neuropore
Which cranial nerve is level with the thalamus?
CN II
Which cranial nerves are level with the mesencephalon?
CN III, IV
The corpora quadrigemina is made up of what fours structures?
The four colliculi: 2 inferior (hearing) 2 superior (vision)
Where is the corpora quadrigemina located?
On the tectum of the dorsal aspect of the midbrain.
What is the function of the corpora quadrigemina?
Reflex centers involving vision and hearing
What cranial nerves are level with the pons?
CN V, VI, VII
What cranial nerves are level with the medulla?
CN VIII, IX, X, XI, XII
What are the three layers of connective tissue for the CNS?
1) dura 2) arachnoid 3) pia
True or false: Not all layers are continuous around the brain and spinal cord?
False: ALL three of the coverings are continuous around the brain and spinal cord (** w/ exception of the dural periosteal layer)
Which menigeal layer is the most external and toughest?
Dural
What are the two layers of the dura mater?
1) periosteal (directly under the skull) 2) meningeal
What does enfolding of the meningeal layer result in?
The formation of openings between the two layers of the dura
What do the dural sinuses function as?
Outflow pathways for venous blood and CSF
The enfoldings are also attached to the inside of the _______ and help anchor the brain.
calvaria
These attachments are extremely rigid, such that when space occupying lessions (tumors or bleeding) are present, they cause _______________.
Herniations
What is the result of cranial herniation?
the brain tissue is squeezed and the function is compromised.
Which layer of the dura is found only in the cranial cavity? What does this layer fuse with?
The periosteal dura. Fuses with the periosteum of the skull at the foramen magnum.
The meningeal layer is continuous into the ____________ and covers the ____________.
vertebral canal and covers the spinal cord
Name 3 structures of the dura:
1) falx cerebri 2) tentorium 3) tentorial notch
What does the falx cerebri separate?
the cerebral hemispheres
What does the tentoriium cerebelli separate?
the cerebral hemispheres from the cerebellum, also limiting the posterior cranial fossa.
Where is the tentorial notch located?
at the opening in the tentorium cerebelli; surrounding the brainstem (midbrain) as it passes out of the middle cranial fossa into the posterior cranial fossa
Where is the superior sagittal sinus located?
on the superior edge of the falx cerebri
where is the inferior sagittal sinus located?
on the inferior edge of the falx cerebri
What does the straight sinus connect?
the inferior and superior sagittal sinuses across the tentorial cerebelli
What is considered the confluens of sinuses
the point posteriorly on tentorium cerebelli where the straight sinus and transverse sinuses join.
Where does the transverse sinus carry venous blood?
toward the internal jugular vein (sinus located at the posterior edge of tentorium cerebelli)
What is the sigmoid sinus continuous with?
the internal jugular vein through the jugular foramen
Describe herniations:
the “squeezing” of nervous tissue through an opening such as the tentorial notch
What are 3 common sites for herniation?
1) subfalcine (cingulate gyrus under the falx cerebri) 2) transtentorial or uncal (uncus through the tentorium cerebelli) 3) tonsillar (cerebellar tonsils through the foramen magnum)
What is embedded between 2 layers of the dura matter?
Blood vessels supplying the meninges
What is the most important blood vessel within the meningies?
Middle meningeal artery
When a skull fracture tears the middle meningeal artery, an arterial blood accumulating between the dura mater and the skull is called an ______________________.
epidural hematoma (actually separates periosteal and meningeal layers)
The arachnoid mater is described as a _________ and ____________ membrane.
delicate and non-vascular
Describe the two layers that make up the arachnoid mater: the continuous and discontiuous.
continuous layer: directly opposed (but not attached) to the meningeal layer of the dura discontinuous: consisting of attachments from the outer arachnoid layer to the pia mater ( arachnoid trabeculae)
What is termed as the potential space b/n the dura and the arachnoid?
subdural space
Veins carrying blood from the brain “bridge” across this potential space to empty into the _______________.
Dural venous sinuses
Can a traumatic occurrence such as whiplash cause these bridging veins to be torn due to shearing forces?
Yes, true.
True or false: The arachnoid and dura are attached.
False: these layers are NOT attached
Vensous bleeding into the space between the dura and arachnoid is termed:
subdural hematoma
What are small extensions of the arachnoid membrane that can be identified along the superior sagital sinus termed?
arachnoid granulations
What do arachnoid granulations protrude through?
protrude through (and extend) into the superior sagittal sinus.
What do the arachnoid granulations function as?
“one-way” gate for uptake of cerebrospinal fluid (CSF) into the venous vascular drainage of the brain
Pia matter is also thought of as __________.
a vascular component
The ______ dura layer is directly opposed to the brain itself
pia
The pia follows the _____________________ into the brain parenchyma until the capillary beds.
penetrating branches of arterioles
What is the space between the pia amd arachnoid maters?
subarachnoid space
Cisterns are known as
enlarged areas of subarachnoid space
Name 6 cranial cisterns:
1) Cistern magna (cerebellomedullary) 2) interpeduncular 3) pontine 4) Cerebellopontine 5) superior 6) lumbar
What can be other structures can be found in the subarachnoid space?
arterial and venous branches
True or false: Bleeding in this region is termed a subarachnoid hemorrhage and can be either arterial or venous.
True
List 4 potential causes of subarachnoid hemorrhage:
1) trauma 2) arteriovenous (AV) malformations 3) stroke 4) aneurysm
After a lumbar puncture what can be identified in the CSF?
blood elements
What are the 2 layers of the pia matter?
1) pia intima (adhered tightly to the spinal cord 2) denticulate ligaments
What is the function of the denticulate ligament?
crossing the subarachnoid space, piercing the arachnoid mater and attaching to the dura.
Is the spinal cord anchored within the spinal canal?
Yes, because in part due to the denticulate ligaments
Ventricles are cavities within the central nervous system, derived developmentally from the _____ ______.
neural tube
Lateral ventricle occur in each of the two cerebral hemispheres. They are continuous with a single midline third ventricle through the interventricular foramen (Monro). This third ventricle occurs on the midline in the sagittal plane and is continuous caudally with the __________________________ in the midbrain
cerebral aqueduct of Sylvius
Where does the cerebral aqueduct empty into?
The fourth ventricle of the pons and medulla.
The fourth ventricle is continuous with the remnants of the _____________ of the ____________.
central canal of the spinal cord.
How does the ventricle communicate with the subararchnoid space?
Through the lateral apertures and one midline aperture
the lateral aperatures aka:
foramina luschka
the midline aperture aka:
foramen of magendie
What do the aperatures allow the CSF to do?
to leave the ventricular system and enter the subarachnoid space.
After CSF has entered the subarachnoid space, it then enters:
the venous system via the dural sinuse
What secretes cerebral sinus fluid?
ependymal cells that line the ventricular system
What is the ventricular lining of the choroid plexus?
capillary beds that extend into all four ventricles
Where and how is CSF produces?
Where: in the subarachnoid space
How: by capillary beds in the meninges
Name two functions of CSF:
1) reduces teh relative mass of the brain
2) cushions it
At what rate is CSF continuously produced at?
500 ml/day
True or false: There is a feedback mechanism to shut down the production of CSF.
False: There is NO feedback system to shut down production
What is the result of the there not being a feedback mechanism?
Any blockage of the flow of CSF results in th build up of interventricular pressure and/or intracranial pressure.
What is obstructive hydrocephalus:
results from blockage of normal flow of CSF out of the ventricular system.
What is a common place for obstructive hydrocephalus to occur?
in the interventricular foramen, cerebral aqueduct and the outflow from the fourth ventricle
Describe communicating hyrocephalus:
results from absorption or circulation problems with CSF.
ex: any abnormality in the ability of CSF to exit the arachnoid granulations such as extremely high venous pressure in the superior sagittal sinus.
The blood brain barrier is composed of a series of _________ components coupled with __________ properties
morphological components coupled with physiological properties
How are the endothelial cells of the blood capillaries in the central nervous system joined?
tight junctions
The tight junctions aide in forming a barrier that allows for what?
selective exchange of only small molecules
True or false: Large proteins, e.g. antibiotics, are restricted from crossing the blood-brain barrier.
True
Are substances such as glucose and amino acids actively OR passively transported across the barrier?
Actively; for the nourishment of the CNS
Which cellular processes are endothelial cells opposed to?
cellular processes of glial cells
How do glial cells control the permeability of the endothelial cells?
By influencing the physiology of endothelial cell membranes
What happens when glial cells are disrupted as in a pathological condition?
They no longer control the endothelial cells AND the barrier is made more permeable
Why must the barrier be patent (present or patient?) at all times?
Because neurons do not have storage capability.
True or false: the barrier is selective in its activity.
True
What do areas of high activty show?
The highest uptake of necessary substances
What has experimental evidence that follows the uptake of radioactively labeled copmounds such as glucose demonstrated?
An increase in perfusion rate of the capillary beds in areas of greater physiological activity along with the greatest areas of O2 uptake.
What does radioactively labled compound imaging allow for?
an “on-going” view of the CNS with areas of higher glucose or O2 activity indicating areas most involved as tasks are being performed.
