General Neuroanatomy 1: Introduction to the nervous system Flashcards
What is in charge of maintaining homeostasis in the body?
Nervous and endocrine systems
What is the nervous system responsible for?
Behaviors
Memories
Movements
What are the three basic functions of the nervous system?
1) Sensing changes with sensory receptors
2) Interpreting and remembering those changes
3) Reacting to those changes with effectors
-Muscular contractions
-Glandular secretions
The nervous system is divided into two subdivisions:
central nervous system (CNS) & peripheral nervous system (PNS)
What does the CNS consist of?
Brain & spinal cord
What does the PNS consist of?
Spinal nerves, cranial nerves, associated ganglia & nerve plexuses
The peripheral nervous system is further subdivided into:
afferent (sensory) & efferent (motor)
Afferent or sensory division transmits impulses from _________ to the _____.
Peripheral organs; CNS
Includes:
- sensory impulses
- special sensory impulses
- visceral sensory impulses
The efferent (motor) division of the PNS is again divided into what?
somatic and autonomic
Somatic nervous system:
supplies motor impulses to the skeletal muscles
The autonomic nervous system (ANS):
Visceral motor (ANS):
supplies motor impulses to cardiac muscle, smooth muscle, and glands
ANS; Visceral motor is further subdivided into:
Sympathetic & parasympathetic nervous system
____________________ is one of the main subdivisions of the autonomic nervous system and governs the function of the GI tract.
Enteric nervous system
The brain consists of:
-Cerebrum
-Diencephalon
-Cerebellum
-Brainstem
The brain stem consists of:
-Midbrain
-Pons
-Medulla oblongata
The CNS process _____________ and ______________ messages.
Incoming sensory; Outgoing motor
CNS is involved in higher-level mental activities such as:
-Learning
-Memory
-Reasoning
CNS is organized as _____ and _______ matter.
Grey and white
Gray matter comprises of:
-nerve cell bodies
-bundles of myelinated nerve fibers
-non-neuronal supportive cells
-glial cells
-neuroglia
White matter consists of:
-Myelinated nerve fibers (tracts or fasciculi)
In the spinal cord, the gray matter forms an _______________ inner core surrounded by white matter.
H-shaped
In the brain, there is a thin outer shell of ___________, the ______, covers the core of the _____________.
grey matter; cortex; white matter
A cluster of nerve cells bodies embedded within the CNS is called:
Nucleus
The aggregation of nerve cell bodies outside the CNS is called:
Ganglion
The PNS includes:
-Spinal nerves
-Cranial nerves
-Ganglia
-Nerve plexuses
What are the major divisions of the CNS?
-Cerebral cortex
-Diencephalon
-Cerebellum
-Brainstem (continues inferiorly as the spinal cord)
General terminology:
Rostral - Caudal
Dorsal - Ventral
Horizontal, coronal, and sagittal
Identify the structures:
1) Cerebral hemisphere
2) Diencephalon
3) Cerebellum
4) Brainstem
5) Midbrain
6) Pons
7) Medulla oblongata
8) spinal cord
Two cells of nervous tissue:
Neuroglia=>
Neurons=>
Neuroglia:
-Support cells of the nervous system
-Nourish and clean up after neurons
Neurons:
-Functional unit of nervous system
-How signals travel to and from PNS to CNS and within CNS
What happens in grey matter & white matter in the CNS:
Grey matter:
-Where synapsing occurs between cells
-Information processing/ passing of signals
White matter:
-Where signals travel from one location to another within the CNS
Where can we find grey matter?
-Cerebral cortex
-Cortical nuclei/diencephalon
-Grey horns of spinal cord
Where can we find white matter?
-Cerebral tracts (corpus callosum)
- White columns of spinal cord
-Spinal pathways
-Peripheral nerves
What does the cerebrum consist of?
-outer cerebral cortex
-Internal region of cerebral white matter
-Nuclei deep within the white matter
Cerebrum comprises of a ______ and __________________ within the anterior and middle cranial fossae.
left and right cerebral hemisphere
In a superior view the ______________ separates the two hemispheres
longitudinal fissure
The cerebral hemisphere can be divided into four main lobes:
-Frontal
-Parietal
-Occipital
-Temporal
-Insula ( hidden portion deep to the sulcus)
Function of the frontal lobe:
-Initiate motor impulses
-Cognition
-Control of voluntary movement
-Motor production of speech (expressive language)
Special senses: smell
Function of the parietal lobe:
-Receive general sensory information
-Process sensory information
General sensations:
-pain, pressure, temperature, touch, tickle, and vibration
Special senses: taste
Function of the occipital lobe:
-Processing visual sensations
Special sensation: vision
Main function of the insula:
taste impulses
Function of the temporal lobe:
-auditory impulses
-Processes memories
Special sensation: auditory information
The fold of the outer surface of the cerebral hemispheres:
Gyri
-separated by furrows called: sulci
The three main sulci in each cerebral hemisphere:
1) Central sulcus: separates the frontal lobe from the parietal lobe
2) Lateral sulcus: superior boundary of the temporal lobe and separates it from the frontal and parietal lobes
3) Parieto-occipital sulcus: separates the parietal lobe from the occipital lobe
The cerebral cortex:
-Outermost layer of the brain
-Associated with higher level processing and functioning
-Divided into right and left hemispheres
-Folded to increase the surface area for information processing:
Gyri: bumps/folds of cortex
Sulci: grooves/indentations
Fissure: Deep sulcus (longitudinal fissure
divides hemisphere (shown in picture))
Central sulcus:
Prominent landmark separating the parietal lobe from the frontal lobe
Identify the structures:
1) Longitudinal fissure
2) Central sulcus
3) Gyrus
4) Sulcus
5) cerebral cortex
6) Cerebral white matter
7) Fissure
Identify the structures:
1) Frontal Lobe
2) Precentral gyrus
3) central gyrus
4) Postcentral gyrus
5) Parietal lobe
6) Occipital lobe
7) Temporal lobe
8) Cerebellum
9) Medulla oblongata
10) Pons
11) Lateral sulcus
Grey matter forms the __________
cerebral cortex
Clusters of nuclei within the white matter are collectively known as ______________
basal ganglia (nuclei)
What are the main components of the basal ganglia?
-Caudate
-lenticular (putamen and globus pallidus) nuclei
(involved in the coordination of motor function)
What are the three classified myelinated nerve bundle groups within the white matter and their function?
1) Association: Fibers join the different parts of the same cerebral hemisphere
2) Commissural: Fibers connect different gyri of one hemisphere to the corresponding gyri of the other hemisphere.
-Corpus callosum is the most extensive commissural fiber bundle located at the bottom of the longitudinal fissure.
3) Projection: fibers include the ascending (sensory) and descending (motor) fibers connecting the cortex to the lower centers of the CNS.
The internal capsule is a thick band of white matter between the caudate nucleus and putamen (two nuclei of the basal ganglia) anteriorly, thalamus, and globus pallidus (one of the basal ganglia) posteriorly.
Identify the structures:
1) head of the caudate nucleus
2) Internal capsule
3) Putamen
4) Thalamus
5) Choroid plexus
6) Pineal gland
7) Corpus callosum
Identify the structures:
1) Association fibers
2) Commissural fibers
3) Projection fibers
What is the general idea about primary sensory areas?
Only a specific type of stimulus can stimulate the receptor to produce its receptor potential:
From the receptor => A course of peripheral nerves (either cranial or spinal) => A pathway (tract) => Thalamus (crude signals/sensation) => Appropriate cortical area for the perception of the sense.
Where is the primary somatosensory area located?
cortex; postcentral gyrus- over the lateral and medial surface of the cerebral hemisphere within the longitudinal fissure.
“Cortical Mapping”- homunculus- This human-like creature illustrates different parts of the human body having different spacial presentations on the cortex.
Where is the primary visual area?
cortex; occipital lobe
Where is the primary auditory area?
cortex; upper portion of temporal lobe
Where is the primary gustatory area?
cortex; insula (insular lobe)
Where is the primary olfactory area?
cortex; medial aspect of the temporal lobe
Identify the structures:
1) Taste
2) Vision
3) Hearing
Identify the structures:
1) Primary olfactory cortex
2) Primary visual cortex
Identify the structures:
1) Gyri of Insula
The largest area of the gyrus generates motor signals for:
-Muscles of the hands
-Muscles of facial expressions
-muscles functionally belonging to the vocal apparatus (initiate fine movements)
Injury here: motor paralysis of the contralateral side of the body
The precentral gyrus:
Extends itself over the medial and lateral cerebral surfaces.
Medial surface: produces motor signals for the leg and foot (area supplied by branches of the anterior cerebral artery, so isolated cerebrovascular accident of this area only causes motor weakness of leg and foot muscles)
Lateral: motor signals for the rest of the body
Primary motor area(cortex):
-Precentral gyrus:
Involved in conscious control of precise skilled, voluntary movements.
Receives input:
Premotor area & supplementary motor areas
-Sensory cortex
-thalamus
-basal ganglia
-cerebellum
Where is the premotor area located?
Frontal lobe, in front of precentral gyrus
What is the function of the premotor area?
Space where patterns of movement are stored
-Learned and several times performed movement is stored as an algorithm into this gyrus.
Where is the frontal eye field located?
In front of pre-motor area of frontal lobe.
What does the frontal eye field control?
Voluntary synchronized movement of the eyes:
Left-side; forces both eyes to move right
Right-side; forces both eyes to move left
If one of the two sides is injured: The other side dominates and forces the eyes to “look into the side of injury”
Where is broca’s area located?
Inferior frontal gyrus of the frontal lobe
Almost always found in the left side of the brain.
What is the function of Broca’s area?
Generating motor signals for vocal apparatus
Injury here: Broca or motor aphasia; patient understands the speech but cannot speak.
Where is Wernicke’s area located?
Around the posterior end of the lateral sulcus in the left temporoparietal junction.
What function does Wernicke’s area serve?
Critical for the understanding of language.
Damage here:
receptive/sensory/Wernicke’s aphasia: empty, fluent speech and a loss of speech comprehension
Speech may be effortless and without hesitancy, but little meaningful information is conveyed
Speaks jumbled meaningless words.
What connects Broca’s and Wernicke’s areas?
White matter tract = Arcuate fasciculus
What is the lesion of the arcuate fasciculus referred to?
conduction aphasia:
-Can comprehend and articulate
-Difficulty repeating heard speech
The common integrative area:
Located among the sensory, visual, and auditory association areas and integrates signals it receives from primary areas.
Redirects those signals into other parts of the brain where it generally creates thoughts and ideas we understand, and then look for appropriate responses.
The functional differences between the two hemispheres:
Focus on notes in the red box
What does the diencephalon include?
Thalami and other structures surround the third ventricle, such as the hypothalamus and epithalamus.
Lateral walls form: Epithalamus most superiorly, thalamus centrally, and the subthalamus and hypothalamus inferiorly.
The thalamus:
Part of the diencephalon:
-Egg-shaped structure consisting of a group of nuclei (mostly sensory)
Plays a crucial role in brain function:
-Processing & distribution center
-Relay & regulating information from outside world and internal milieu => cerebral cortex & sustaining cortico-thalamo-cortical communication
-Consciousness
-sleep
-attention
-memory
-sensory
motor functions
All senses (except smell) to certain sensory areas of the cerebral hemisphere.
Hypothalamus:
-Inferior & medial to the thalamus
-Center of autonomic nervous system
Controls:
-emotions
-body temp
-eating
-drinking
etc….
Regulates major components of the endocrine system through pituitary gland.
Epithalamus:
Small region posterior and superior to the thalamus
Pineal gland; regulates circadian rhythm & distribution of pigment melanin of the skin
Cerebellum location:
Contained within posterior cranial fossa, under tentorium cerebelli, behind medulla and pons, separated by the fourth ventricle.
The two cerebellar hemispheres are connected by what?
vermis: worm-like structure
Deep cerebellar nuclei:
-Fastigial
-Globose & emboliform (interposed nuclei)
-Dentate
Primary function of the cerebellum:
-Coordination of voluntary movements
-Maintaining posture
-Balance
Identify the structures:
1) Cerebellar nuclei:
a) Fastigial
b) Globose
c) Emboliform
d) Dentate
2) 4th ventricle
3)Superior cerebellar peduncle
4) Vermis
Major functions of the brainstem include:
1) acts as a passageway for all ascending and descending tracts
2) Contains the nuclei of cranial nerves III to XII
3) It regulates the automatic behaviors required for survival, such as respiration
The midbrain is located where?
Connects to pons inferiorly & diencephalon superiorly
The posterior aspect of the midbrain has four elevations known as:
Superior & Inferior Colliculi
Nuclei deep in these colliculi relay:
-Visual reflexes
-Auditory reflexes
Ascending tracts occupy the white matter of the midbrain behind the _______
crus cerebri
Several nuclei are embedded within the white matter of the midbrain, some of which include the cranial nerves ___, ____, and ___.
CN: III, IV, V
Oculomotor, Trochlear, Trigeminal
The other nuclei include the red nucleus & substantia nigra
Red Nucleus:
Associated with the rubrospinal tract (part of extrapyramidal pathways)
Substantia Nigra:
Functionally linked to the basal ganglia regulating voluntary movements.
In the transverse section of the midbrain, the internal structures can be divided into three main areas:
Tectum: Roof, behind cerebral aqueduct
Tegmentum: From cerebral aqueduct => substantia nigra & cerebral peduncle
Periaqueductal gray matter: Around cerebral aqueduct - site of production of natural painkillers (endorphins & enkephalins)
CN ____, ___, & ____ emerge from _______________.
CN: VI, VII, VIII; pontomedullary sulcus
Cranial nerve V appears at the anterolateral surface of the pons.
Gray matter of the pons is organized as nuclei embedded in the white matter.
Some of these nuclei are related to the CN V, VI, VII, VIII. The other nuclei include _________
The pontine nuclei
The pontine nuclei:
Relay center for motor pathways between cerebrum and cerebellum to coordinate voluntary movements.
Two importnat nuclei are found in the pons that add more control to the respiration:
pneumotaxic area
apneustic area
The medulla takes what shape and is separated from the pons by what?
pyramidal; transverse pontomedullary sulcus (superiorly)
continuous with the spinal cord inferiorly
Lateral to the pyramid of the medulla is a second elevation:
The olive: overlies the inferior olivary nucleus
What nerves emerge from the anterolateral surface of the medulla oblongata?
CN: IX, X, XI, & XII
At the junction of the medulla and spinal cord one can find the ________________.
Decussation of pyramids;
corticospinal tracts cross each other here
The grey and white matter of the medulla in the superior portion is arranged how?
Gray matter is embedded in the white matter as clusters of nuclei.
These nuclei clusters are associated with:
CN V, VIII, IX, X, XI & XII.
What are the major nuclei of the medulla oblongata?
Inferior olivary nucleus
Nucleus gracilis & Nucleus cuneatus
Inferior olivary nucleus:
relay center for proprioceptive information to the cerebellum
Nucleus gracilis & Nucleus cuneatus:
associated with the posterior column-medial lemniscus pathway
How does the reticular formation work?
Receives a lot of sensory signals from different parts of the body, including special senses such as vision and hearing.
Prevents overload by acting as a filter:
Filters 99% of sensory signals & prevents the from being consciously perceived.
RAS(ARAS) system:
Reticular activating system or ascending reticular activating system:
Responds to some stimuli potentially disrupting a relatively consistent flow and unchanged level of intensity of incoming signals.
ex) Falling asleep with the air conditioner running and the constant humming sound of the air conditioner will be filtered out by the reticular formation; when the alarm sounds off the person will wake up
Involved in regulating the circadian rhythm and sleep-wake cycle.
Inputs to spinal cord; reticulospinal pathway: contributes to muscle tone
-General anesthetics work to suppress this system
