CH.13 Flashcards
Lateral ventricles serve which brain structures?
Cerebrum: cerebral hemispheres (cortex, white matter, basal nuclei.
Third Ventricle serves which brain structures?
Diencephalon (thalamus, hypothalamus, epithalamus), retina
Cerebral aquaduct serves which brain structures?
Brain stem: midbrain, pons, medulla oblongata
-cerebellum
Central canal serves which CNS structure?
spinal cord
What are the major diviions of the brain?
Cerebrum, diencephalon, cerebellum, brain stem.
Where is CSF made?
Made inside all of the ventricles
Describe the brain ventricles
- Continuous with each other and the central canal
- lined with ependymal cells
- provide CSF to nearby brain regions
Anterior horn of the lateral horns serve what brain region?
frontal lobes
Posterior horn of the lateral horns serve what brain region?
occipital lobe
Inferior horn of the lateral horns serve what brain region?
the temporal lobes and insular lobes of the cerebral cortex
Main body of the lateral ventricles serve what region of the brain?
The parietal lobes
What is the function of the cerebral aqueduct?
drains CSF from third ventricle into the fourth ventricle
What is the function of the interventricular foramen (foramina)?
Allow CSF to drain form the lateral ventricles into the third ventricle
Where does CSF go from the fourth ventricle?
Two places
- into the central canal
- back up into the brain into the subarachnoid space.
How does CSF escape the fourth ventricle?
Via apertures
- two lateral
- one medial
Why does the cerebrum have wrinkles on the external surface?
To increase surface area to make room for more neurons.
Describe the gross anatomy of the cerebrum
Three layers. Deep gray (neuronal soma), cerebral white matter (axonal tracts), cerebral cortex (neuronal soma-outer gray matter) -separated into the left and right hemispheres
The deep gray matter is always near what?
The lateral ventricles
What is a fissure?
A very large groove between structures in the brain
What is a sulcus?
small indentation or a small groove (sulci plural)
What is a gyrus, gyri plural?
Bumps in the brain caused by fissures and sulci.
What lobes are part of the cerebral cortex?
Frontal, parietal lobes, occipital lobes, temporal lobes, insular lobes
What separates the parietal and frontal lobes?
The central sulcus
What separates the cerebral cortex from the cerebellum?
The transverse cerebral fissure
What separates the temporal lobes from the parietal and frontal lobes?
The lateral sulcus
What is the insular lobe?
More gray cortex matter underneath the temporal, frontal and parietal lobes. must pry the brain open at the lateral sulcus to see.
What is the longitudinal fissure?
Fissure that runs anterior to posterior and separates the cerebrum into the left and right hemispheres.
What is unique about the central sulcus?
It is the only sulcus that runs from the longitudinal fissure all the way down to the lateral sulcus. Making a clear marker between the frontal and parietal lobes.
What separates the occiptal lobe from the parietal lobes?
The parieto-occipial sulcus. Not very distinct but seen very well from a medial view.
Where are the precentral and postcentral gyrus and what are their functions?
Rostral and caudal to the central sulcus. Precentral gyrus (frontal lobe) =primary motor cortex Postcentral gyrus (parietal lobes)= primary somatosensory cortex
What are associational areas?
They are adjacent to their respective functional regions.
-their function is not a primary function. they just integrate that information and start putting things together in the brain.
What are some functional regions of the cerebral cortex?
Primary motor cortex, primary somatocensory cortex, primary auditory cortex, primary visual cortex.
Where is the primary auditory cortex?
On the superior lip of the temporal lobe and dives down and faces the insular lobe as well.
Where is the primary visual cortex?
At the point of the occipital lobe and dips into the longitudinal fissure and runs internally as well.
Where is somatotopy revelant?
Primary motor cortex and primary somatosensory cortex.
When sensory information comes in, where is the first place it goes to?
Thalamus then it lands somewhere in the primary somatosensory cortex
How is information integrated in our brain?
sensory Information gets processed by a bunch of interneurons and associational areas give it meaning and eventually a blueprint is made and sent to the primary motor cortex and the primary motor cortex says yes or no to the action.
-essentially, information gets processed by a bunch of interneurons that inevitably activate the primary motor cortex so that we can have a motor response to those sensations.
White matter in the cerebrum can be classified into what?
Commisural fibers, associational fibers, projection fibers
What are commisural fibers?
Axons running from one hemisphere to the other.
- from a medial view they look like little dots.
- these fibers are going to cross the midline of the brain.
- the vast majority of axons that cross the midline of the brain do so at the very largest commissure (corpus callosum)
What is the corpus callosum?
largest commissural fiber in the cerebral white matter
What are projection fibers/tracts?
Running north-south in the CNS
Cortex lower cns areas
example: internal capsule
What are associational fibers?
Axons traveling on the same side of the hemisphere (intrahemispheric)
- going from one gyrus to the next
- can skip gyri and can be long or be short
- contribute to the white matter that is branching off towards the edge of the cerebrum
What makes the deep cerebral gray matter?
Basal nuclei (ganglia is cluster of cells bodies in the PNS not CNS)
- basal forebrain nuclei
- claustrum
- amygdala
What is the function of the Basal nuclei in the deep cerebral gray matter?
- Initiates and terminates body movements
- –example people with parkinsons want to initiate movement and struggle, its because they have a problem with this area
- suppress unwanted movements by regulating the primary motor cortex (ceo guy that likes to say yes to everything)
- –example: people who tremor and cannot stop that tremor they have a problem with the basal nuclei
What makes the diencephalon?
Thalamus, hypothalamus, pituitary gland, pineal gland, posterior commissure.
Describe the structure of the thalamus
Right and left hemisphere
-held together by the interthalamic adhesion or the intermediate mass of the thalamus
What is the thalamus?
- has a bunch of subnuclei that are responsbile for relaying sensory information to the cortex
- giant relay station
What is the function of the hypothalamus?
- has an abundance of subnuclei (about 12)
- plays an important role in homesotasis, making sure all of the biological variables are kepy in a tight range—> temperature, hunger, lung, heart function
What forms the walls of the third ventricle?
the hypothalamus
-forms two columns one on either side of the lower portion of the third ventricle
Where is the pituitary gland located?
Hangs off of the hypothalamus on the anterior side of the brain
What is the infundibulum?
a cherry stem that connects the pituitary gland to the hypothalamus
What are mammillary bodies?
Nuclei (2) found on the inferior surface of the hypothalamus. (anterior side)
The pineal gland and posterior commisure make up what?
The epithalamus
What is the pineal gland?
- Single gland
- epithelial derived, hormone producing tissue
- produces melatonin
- on the posterior side
What is melatonin?
Hormone that is responsible for helping regulate your circadian rhythm and help give you that sleepiness towards the end of the day.
-highly integrated with visual information.
What is the posterior commissure?
- axons that are crossing the midline
- found inferior to the pineal gland and is part of the epithalamus
Where is the hypothalamus located?
Inferior and slightly rostral to the thalamus
What composes the midbrain?
cerebral peduncles
cerebral aqueduct
corpora quadrigemina
What makes the brain stem?
medulla oblongata, pons, midbrain
What are the cerebral peduncles?
- part of the midbrain (brain stem)
- composed mostly of motor axons from the cortex to the cerebellum and spinal cord
- dive into the pons
What do the cerebral peduncles look like and where are they?
look like white columns, vertically striped appearance.
- located on the ventral, slightly lateral aspect of the mid brain.
- look like they are diving into the pons
What and where is the cerebral aqueduct?
- passes through the center of the midbrain
- connects the 3rd and 4th ventricle
What is the corpora quadrigemina?
- means four bodies
- nuclei that form four bumps on the dorsal aspect of the midbrain
What do the superior colliculi of the corpora quadrigemina do?
visual reflexes
- typically the reflex of turning to see what caught your eye in your peripheral vision
- makes your neck muscles activate to turn your face towards what caught your eye
- protective type of reflex
What do the inferior colliculi of the corpora quadrigemina do?
audtiroy reflexes
-hearing something from behind like a door slamming and you look at the person who did it.
What is the pons and where is it?
Pons = bridge between brain stem and the cerebellum
- contains a superior pontine and inferior pontine border
- superficial transverse fibers horizontal axons (stripes)
- ONLY A VENTRAL structure.
Where are the fibers of the pons diving into?
The cerebellum specifically the middle cerebellar peduncles
What is the middle cerebella peduncle?
Motor axons that are diving in from the pons into the cerebellum.
Motor tract that leads to the cerebellum so that it is involved in the motor plan.
What is the medulla oblongata, where is it and what is its main function?
- homeostasis
- most inferior/caudal portion of the brain, not CNS
- Extends from the inferior pontine border to the foramen magnum.
What are pyramids (pyramidal tracts)?
- structures found on the ventral aspect of the medulla
- motor tracts that came from the cerebral peduncles
- smaller amount of axons traveling here because some of the axons in the cerebral peduncles stopped there and went in a different direction
- these axons will continue down the spinal cord until they reach their somatic motor neurons.
What are olives?
Nuclei called olivary nudlei that form bulges just lateral to the pyramids
-function in sensory relay station
What is the midline raphe?
groove that runs down the middle of the pons and brain stem.
What is the motor decussation (pyramidal decussation, decussation of the pyramids)?
the area of the brain where MOTOR information crosses to the other side of the brain.
-Example: an axon traveling down the left cerebral peduncle will cut through the pons and down the left pyramidal tract and will cross over to the right side of the spinal cord here.
In what ways does the medulla function in homeostasis?
Collaborates with the hypothalamus in regulating blood pressure, regulating breathing, cough reflex and sneezing (getting rid of bad things from our body)
What is the second largest structure in the brain?
The cerebellum
What is the arrangement of the cerebellum and what is it similar to?
- two hemisphere
- Has a cortex (outer gray matter) with many folds called folia
- -White matter with tracts called arbor vitae
- deep gray matter
What is the vermis?
the midline structure of the cerebellum
-similar to the interthalamic adhesion
What are folia?
external gray matter of the cerebellum
- cerebellar cortex
- wraps around the arbor vitae
What do the anterior and posterior lobes of the cerebellum function in?
Responsible for motor coordination for the trunk, limbs, basically neck down.
Where is the flocculonodular lobe located and it’s function?
- located pressed up against the posterior aspect of the medulla oblongata and the anterior portion of the cerebellum.
- functions in equilibrium
- –helps with head and eye coordination
- –when we get out of balance what is really happening is that our body is telling us our head is not in the right place or your eyes are in a strange position.
What are the protective coverings of the CNS?
Skull-brain
Vertebrae- spinal cord
Meninges- around the brain and spinal cord
What are meninges (meninx-single)?
Connective tissue sheaths around the brain and spinal cord that are in a layer type of fashion
What are the layers of the meninges from superficial to deep?
Dura mater
Arachnoid Mater
Pia Mater
Where is CSF found?
Inside and outside of the brain
Where is the subarachnoid space?
Between the pia mater and the arachnoid mater
What is the purpose of the subarachnoid space?
CSF exits from the fourth ventricle via apertures and into this space
Where is the subdural space?
Below the dura mater and above the arachnoid mater.
What makes up the true dura mater around most parts of THE BRAIN?
The periosteal (bone periosteum) and meningeal layers
What happens to the dura mater when it is covering a deep fissure like the longitudinal or the transverse fissures?
The dura mater splits
- the periosteal layer (periosteum) never leaves the bone.
- the meningeal layer separates from the periosteum and follows the brain down into the fissure
What is a dural septum and give an example?
- when the dura mater splits, the meningeal layer follows the brain into the fissure. The dura mater is splitting on two sides so two portions of the meningeal layer are going down the fissure.
- the dural septum is the double layer the meningeal layer of the dura mater makes when it splits over fissures.
- example: Falc Cerebri, located in the longitudinal fissure
What is a dural venous sinus?
- a fluid filled cavity with CSF and veins
- formed by the separation of the meningeal layer and the periosteal layer of the dura mater.
- drain out blood and CSF from brain tissue
The combination of all of the dural venous sinuses in the brain at the base of the skull will form what?
The internal jugular vein
What is the function of dural septa?
to separate things within the cranial cavity and keep them in place.
-box of fancy chocolates analogy (cardboard separating the paper covers chocolates is the dural septa)
What is the Falx Cerebri and the Tentorum Cerebelli?
Falx Cerebri- dural septum that separates the left and right hemispheres down the longitudinal fissure
Tentorum Cerebelli- separates the cerebellum from the cerebrum
What would happen if you didn’t have dural septa?
Your brain would slosh around and put a lot of strain on your cranial nerves
When does the spinal cord start?
When the medulla oblongata exits the formaen magnum, that is when it starts.
What are the functions of the spinal cord?
- Sensory and motor innervation of the whole body inferior to the head (neck down)
- Two-way conduction pathway between the brain and body iinferior to the head (neck down)
- Major integration center for reflexes inferior to the head (neck down)
What is the difference between a spinal and cranial reflex.
Spinal reflex involves spinal nerves
Cranial reflex involves cranial nerves
Where are the spinal enlargements and why are they bigger?
Cervical
lumbar
sacral
-lots of gray matter
What is the conus medularis?
The caudal most point of the spinal cord.
-the end of the spinal cord.
What is the filum terminale?
- pia mater coming out of the conus medularis and acting like a tendon and anchoring the spinal cord in it’s place
- extends from the conus medularis to the coccyx
What is the cauda equina and why is it there?
Spinal nerves that are surrounding the filum terminal
- caudal to the conus medularis
- these nerves must travel south before exiting their respective intervertebral formaen.
Around what vertebra does the spinal cord stop?
L1
How do the spinal nerves exit the vertebra?
Cervical-above the vertebra
-The rest is below
How many vertebra are there?
Cervical= 7 Thoracic= 12 lumbar= 5 sacaral= 5
Why do we have a cauda equina?
Spinal cord stops around L1. So all of those nerves after L1 need to travel south together before they can exit.
-So typically the spinal nerve segments sit superior to their exit.
Where is the lateral horn present?
T1-L2
What kind of neurons are in the dorsal horn?
Multipolar interneurons
What kind of neurons are in the lateral horn?
multipolar interneurons Motor specific to the sympathetic nervous system
Ventral horn has what kind of neurons?
Multipolar neurons that synapse on skeletal muscle
What is the gray commisure?
Gray matter beween the horns
What is the dorsal median sulcus and the ventral median fissure?
- little groove on the dorsal side
- big groove on the ventral side and has a lot of vasculature that serves the spinal cord
What is involved with the ventral root?
Motor neurons from the ventral horn
What is involved with the dorsal root
Sensory neurons from the dorsal horn
What is the dorsal root ganglia (ganglion single)?
Where sensory unipolar neurons live.
When does the spinal nerve start?
When the dorsal and ventral roots come together and are ensheathed with epineurium.
What happens to the white matter as you travel superiorly (rostral)?
It accumulates and gets larger
Where do we find lateral horns
In the Thoracic cavity and L1-2
Which spinal cord segment is the largest?
Cervical
The spinal cord enlargements tend to have what?
large ventral horns for motor movement and control of the limbs
What kind of motor units does the thoracisc segment of the spinal cord have?
Large—so one neuron that innervates a bumch of areas. why? because there is no need for fine control there
What is making up the majority of the dorsal root?
The central process of the unipolar neurons living in the dorsal root ganglion
Which root is purely sensory?
Dorsal root
Which root is purely motor?
ventral
What is a tract?
bundle of axons with similar function traveling together
Ascending tracts carry what?
Sensory information
Descending tracts carry what?
Motor information
What is the pattern with naming spinal cord white matter tracts?
start where the axon begins and end with where it ends
