Introduction to the Nervous System Flashcards
What is Gray matter?
A collection of neuron cell bodies
What is a nucleus of the gray matter?
A cluster of neuron cell bodies that are morphologically distinct from other neurons
What is a lamina of the gray matter?
layer or band of spinal cord made of gray matter
What are bodies of gray matter?
Usually nuclei (ex: geniculate bodies/nuclei of thalamus)
What is the cortex of gray matter?
Fray matter located on a surface (cerebral and cerebellar cortex)
What is white matter?
An aggregation of neuronal processes/axons
What is a tract of white matter?
A collection of neuronal fibers/ axons that are anatomicall yor functionally distinct
What is a fasciculus of white matter?
Bundle of axons/fibers, same as tract
What is a lemniscus of white matter?
Ribbon or band of axons/fibers, same as tract
What is a funiculus of white matter?
Cord or column of white matter in spinal cord that includes several fasciculi/tracts
What is the ascending fibers/axons of white matter?
Rostrally (up towards the nose), upstream or cranially
What is the descending fibers/axons white matter?
Caudally or downstream
Are there any nerves in the CNS?
No, nerves are found external to the CNS
What are the divisions of the central nervous system?
Spinal Cord
Brainstem
Cerebellum
Cerebrum
What is the brainstem?
The part of the brain that connects the spinal cord to the cerebrum and cerebellum
What is the brainstem also referred to as?
Bulb or bulbar
Does the brainstem contain gray matter?
Yes it includes gray matter areas or nuclei
Does the brainstem contain white matter?
Yes, white matter includes ascending and descending tracts of fibers
What are the three divisions of the brainstem?
Medulla
Pons
Midbrain
What are the gray matter areas of the medulla?
Inferior Olivary Nuclei
Cranial nerve nuclei
What are the inferior olivary nuclei?
Large nuclei
Paired nuclear complex (right and left)
Forms landmarks on the ventrolateral surface called olives
What are the cranial nerve nuclei of the medulla?
clusters of neurons that contribute fibers to or receive fibers from a cranial nerve
What cranial nerves are part of the cranial nerve nuclei of the medulla?
XII XI X IX VIII (part of complex) V (part of complex)
What are the white matter areas of the medulla?
Both ascending and descending fiber tracts
Medullary pyramids
What are medullary pyramids?
Paired (right and left)
Landmark structures on ventral surface
Comprised of descending fibers/axons
What are corticospinal fibers/axons?
Axons from cerebral cortex to spinal cord
Provide motor control
What are inferior cerebellar peduncles?
Restiform bodies
Paired structures that help attach the cerebellum to the medulla
What is a peduncle?
Stalk or stem
What is the function of inferior cerebellar peduncles?
Consists mostly of axons going to and from the cerebellum to and from the medulla
What are the two parts of the pons?
Dorsal pons = posterior part
Ventral pons = Basilar Pons (anterior part)
What matter does the dorsal pons consist of?
Comprised of many gray and white matter areas including the cranial nerve nuclei of: VIII (part of) VII VI V (part of)
What matter make up the ventral pons?
White and Gray Matter
What are pontine nuclei ?
Collection of neuron cell bodies in the ventral pons
Which part of the pons are pontine nuclei found?
Ventral pons
What is the function of the pontine nuclei?
- Receives input from neurons of the ipsilateral cerebral cortex
- Projects axons to the contralateral side of the cerebellum
What forms the middle cerebellar peduncle?
Project axons from the pontine nuclei that travel to the contralateral side of the cerebellum and connect the pons to the cerebellum
What is the midbrain?
Most superior part of the brainstem
What does the midbrain consist of?
Has part of the brain ventricular system
What divides the midbrain into 2 portions?
The cerebral aqueduct (of Sylvius)
What are the two parts of the midbrain?
Dorsal Midbrain
Ventral Midbrain
What is the dorsal midbrain also known as?
Tectum or roof of the midbrain
What is included in the dorsal midbrain?
Includes 2 pair of nuclei, superior and inferior colliculi
What is the function of the neurons of the superior colliculi?
Concerned with coordinating certain reflexes in response to visual/auditory data
What is the function of the neurons of the inferior colliculi?
Involved in the conscious auditory pathway
What is the ventral midbrain formed by?
Formed by a pair of cerebral peduncles that include both white and gray matter
What nuclei does the of the ventral midbrain gray matter consist of?
Cranial nerve nuclei
Substatia nigra
Which cranial nerve nuclei are part of the ventral midbrain?
III
IV
Part of V
What is the function of the substantia nigra?
motor control
What type of matter does the superior cerebellar peduncles consist of?
white matter
What does the white matter of the superior cerebellar peduncles do?
fibers connect cerebellum to midbrain and cerebrum
what makes up the cerebellar cortex?
most of the gray matter is distributed on the outer surface forming cerebellar cortex
how does the cortical surface of the cerebellum appear?
The coritcal surface is highly folded into a series of folia or leaf- like folds
What are the deep/subcortical cerebellar nuclei?
some gray matter (nuclei) that are embedded in the medullary center
What forms the center or medullary center of the cerebellum?
White matter
Which pairs of peduncles connect the cerebellum to the brainstem?
inferior cerebellar peduncles
Middle cerebellar peduncles
superior cerebellar peduncles
what part does the inferior cerebellar peduncles connect on the brainstem?
cerebellum to medulla
what part does the middle cerebellar peduncles connect on the brainstem?
cerebellum to pons
what part does the superior cerebellar peduncles connect on the brainstem?
cerebellum to midbrain
What is the function of the cerebellum?
Receives input from most sensory systems and cerebral cortex
- influences the activity of skeletal muscle related to:
1) posture
2) equilibrium
3) coordination/control of movements
What two major parts make up the cerebrum?
Diencephalon
Telencephalon
What is the diencephalon?
Forms the core of the cerebrum
Found in between the cerebral hemispheres
what type of matter is the diencephalon made of?
mostly gray matter, with some white matter
What separates the two halves of the diencephalon into left and right?
separated by the Third (III) ventricle
What parts make up the diencephalon?
Hypothalamus
Thalamus
epithalamus
Subthalamus
what is the thalamus?
a collection of neurons/nuclei
What is the function of the thalamus?
- relay most sensory information to the cerebral cortex
- involved in motor pathways
- influence other brain activity (behavior, emotions, consciousness)
where is the hypothalamus located?
below thalmus
what is the function of the hypothalamus?
- A principle autonomic center of the brain; helps to control the sympathetic and parasympathetic nervous systems
- helps to control the activity of the pitutiary gland (feeding behavior, temperature regulation, emotions, etc.)
where is the epithalamus located?
above the thalamus
What does the epithalamus include?
pineal gland
Where is the subthalamus located?
under the thalamus and posterior to the hypothalamus
what is the function of the subthalamus?
includes the subthalmic nucleus that is involved in motor pathways
what is the telencephalon?
cerebral hemispheres
what are the right and left cerebral hemispheres separated by?
longitudinal cerebral fissure
what is the gray matter in the telencephalon organized as?
cerebral cortex
corpus striatum
what is the cerebral cortex
made of mostly gray matter and covers the surface of each hemisphere
What is the corpus striatum?
striped body
- nuclei located deep in (at the base of) each hemisphere
- important in motor control functions
what is the white matter of the tenecephalon organized as?
Medullary center or core
What three types of fibers comprise the medullary center (white matter)
- association fibers/axons
- commissural fibers
- projection fibers
what are association fibers?
connect different cortical areas within a single hemisphere
what are commissural fibers?
connect a cortical area of one hemisphere to a (similar) cortical area of the opposite hemisphere
do commissural fibers decussate from one hemisphere to the other?
Yes commissural fibers decussate or cross from one hemisphere to the other
what is a projection fiber?
connects an area of cerebral cortex to a subcortical area or a subcortical area to a cerebral cortical area
what is an internal capsule?
many projection fibers that converge to form a compact zone of axons which are positioned deep in each hemisphere
what is the importance of projection fibers?
used for majory sensory and motor pathways and can be damaged in strokes
what are gyri?
a series of folds formed by highly convoluted surface of the cerebral hemispheres
what is a sulci?
The grooves or furrows that intervene between adjacent gyri
what are the five anatomical lobes of each cerebral hemisphere?
frontal lobe parietal lobe temporal lobe occipital lobe Insula or island of Reil
what is the ventricular system of the brain?
Seires of fluid-filled spaces within the brain that is derived from the neural canal of the embryonic neural tube
What lines the ventricular system of the brain?
ependymal cells
What does the ventricular system contain?
Choroid plexus
What does the choroid plexus secrete?
Cerebral spinal fluid
Where does CSF go after being circulating in the ventricles?
Circulates out of the ventricles into the subarachnoid space around the brain and spinal cord.
Where is CSF resorbed?
Arachnoid villi into the superior sagittal venous sinus
What is the total volume of CSF?
80-150 ml
How much of the 80-150 ml fills the ventricular spaces?
About 1/3
How much CSF is produced per day?
600 ml per day that is constantly produced and resorbed
What are the lateral ventricles?
paired chambers within each cerebral hemisphere and includes the choroid plexus
What are the parts of the lateral ventricle?
Anterior horn (frontal lobe) Body (pre/post central gyri) Posterior horn (occipital lobe) Inferior horn (temporal lobe) Collateral trigone (where body, posterior horn and inferior horn intersect)
What is the III ventricle?
Unpaired space between the two halves of the diencephalon (includes the choroid plexus)
What is the interventricular foramina (of Monro)
Paired; connects each latern ventricle (anterior horn) to the II ventricle
What is the cerebral Aqueduct (of Sylvius)
ventricular canal that resides within the midbrain; connects the III ventricle to the IV ventricle
What is the IV ventricle?
Unpaired chamber; includes some choroid plexus
What forms the roof of the IV ventricle?
Cerebellum
What forms the floor of the IV ventricle?
Pons and Medulla
What is another name for the floor of the IV ventricle?
Rhomboid fossa
What are the lateral aperatures (foramina of Luschka)?
Paired; connects the IV ventricle to the subarachnoid space
What is the pontine cistern?
Subarachnoid space on ventral aspect of pons.
Located at pontomedullocerebellar angle
What is the median aperature?
Unpaired; connects the IV ventricle to the subarachnoid space (Cisterna magna)
What is the cisterna magna?
Subarachnoid space between medulla and cerebellum
Dorsal to the medulla
What is another name for the cisterna magna?
Cerebellomedullary cistern (between medulla and cerebellum)
Trace the CSF circulation starting at the lateral ventricle
Lateral ventricle -> foramen of monro -> III ventricle -> cerebral aqueduct -> IV centricle -> lateral and median apertures -> subarachnoid space -> reabsorbed at arachnoid villi -> dural venous sinus
What is hydrocephalus?
Excess CSF, often related to increases CSF pressure
What is obstructive hydrocephalus?
Obstruction of CSF criculation out of ventricles -> ventricular hypertrophy (increased CSF upstream of obstruction)
What is communicating hydrocephalus?
Excess CSF in entire system (internal and external to the brain)
Often due to poor resorption or over secretion
What is external hydrocephalus?
Increased CSF in subarachnoid space
Common in senile dementia
What is the clinical significance of hydrocephalus?
Increased cranial pressure can result in structural and functional damage
- Neurological defects and excruciating head aches
What is papilladema?
Swelling of the optic disc
What is the caudate nucleus?
Paired
Nucleus involved in motor control that lies along the lateral ventricle
What is the head of the caudate?
In the lateral wall of the anterior horn of the lateral ventricle
What is the body of the caudate?
In the lateral wall of the body of the lateral ventricle
What is the tail of the caudate?
In the roof of the inferior horn
What is the amygdala?
almond sized and shaped nuclear complex
Where is the amygdala found?
Positioned just beyond the tip of the inferior horn and the tail of caudate in the temporal lobe
What is the function of the amygdala?
It is a limbic structure
- involved in emotions, behavior, autonomic and endocrine chages
What is the hippocampus?
Gray matter structure (cortex) that is involved in memory and emotions
Where is the hippocampus found?
Lies along the floor of the inferior horn of lateral ventricle (in the temporal lobe)
What is the fornix?
Major tract of white matter fibers that emerge from the hippocampus and projects largely to the diencephalon (mammary body and hypothalamus)
What is the function of the fornix?
interconnects limbic system structures
What is the corpus striatum?
Gray matter positioned dee in each hemisphere; involved in motor control
What are the two nuclei of the corpus striatum?
Caudate nucleus
Lenticular nucleus
What are the two parts that make up the lenticular nucleus?
globus pallidus (medial) putamen (lateral)
What is the internal capsule?
White matter structure that consists of projection fibers that provide connections to and from neurons of the cerebral cortex
What are the 3 parts of the internal capsule?
anterior limb
Genu
Posterior limb
What is the anterior limb of the internal capsule?
Separates caudate from the lenticular nucleus
What is the genu of the internal capsule?
“knee between anterior and posterior limbs
What is the posterior limb of the internal capsule?
Lenticulothalamic portion
What is the clinical significance of the internal capsule?
Can be damaged in strokes
What is the septum pellucidum
Partition like structure that separates the anterior horns of the lateral ventricles
What is the interthalamic adhesion or massa intermedia?
Gray matter bridge that connects two halves of the thalamus
