NEUROANATOMY Flashcards
The meninges are the outer coverings of what structures?
Brain and Spinal cord
Name the 3 meninges starting with the outermost layer
1) Dura mater- outermost layer, strongest and thickest
2) Arachnoid Mater- Middle layer, thin membrane encloses the subarachnoid space
3) Pia mater- innermost layer, follows contour of cortex, composed of 2 layers; highly vascular and sheaths blood vessels as they enter the brain
What is the cerebrospinal fluid (CSF) filled space between the arachnoid mater and pia mater?
Subarachnoid Space
Acts as a relay center for sensory information (except smell) to the cerebral cortex. It plays a key role in consciousness and alertness.
Thalamus
Regulates autonomic functions, including temperature control, hunger, thirst, sleep, and hormone release via the pituitary gland.
Hypothalamus
bundles of axons that share a common origin and destination
Tracts
The largest commissure, connecting the left and right cerebral hemispheres
Corpus Callosum
Part of the brainstem, it relays signals between the cerebrum and cerebellum and plays a role in sleep and respiration.
Pons
Involved in memory, auditory processing, and emotion (limbic system, hippocampus, Wernicke’s area for language comprehension).
Temporal Lobe
Processes visual information from the eyes
Occipital Lobe
Separates the left and right cerebral hemispheres
Medial Longitudinal Fissure (MLF)
Rolandic Fissure (Central Sulcus
Separates the frontal lobe (motor cortex) from the parietal lobe (sensory cortex).
Divides the temporal lobe from the frontal and parietal lobes
sylvian fissure
Parieto-Occipital Fissure
separates frontal and parietal lobe from temporal
Located Between the Midbrain & Medulla
Pons
Cerebellum
Located in the Posterior Fossa
Located in the Posterior Fossa
CSF
Lateral Ventricles →
Interventricular Foramen (Foramen of Monro) →
Third Ventricle →
Cerebral Aqueduct (Aqueduct of Sylvius) →
Fourth Ventricle →
Foramina of Luschka & Magendie (Exit Points) →
Subarachnoid Space (Cisterna Magna
CSF CIRCULATION
Normal Volume: 125–150cc
Replaced 3–4 Times Daily
CSF
Circle of Willis:
Provides collateral circulation if an artery is occluded
Dura mater
The outermost, tough, and fibrous layer
Arachnoid mater
The middle layer, web-like in appearance, involved in cerebrospinal fluid circulation
The innermost, delicate layer that closely adheres to the brain and spinal cord
pia
A horizontal fold that separates the cerebellum from the occipital lobes of the cerebrum. It helps support the brain and prevents excess
Tentorium Cerebelli
Tentorium Cerebelli
A smaller fold that separates the two hemispheres of the cerebellum
A smaller fold that separates the two hemispheres of the cerebellum
Falx Cerebri
It lies between the cerebellum and the inferior surface of the cerebrum, creating a structural barrier
Tentorium Cerebelli
Falx Cerebelli
an important dural reflection. Here’s what you need to know:
Structure: It is a sickle-shaped fold of dura mater.
Location: It forms a vertical partition between the two cerebellar hemispheres.
Function: Helps stabilize and support the cerebellum by preventing excessive movement.
What are cranial nerves?
Nerves that emerge directly from the brain and brainstem, primarily responsible for sensory and motor functions of the head and neck.
There are 12 pairs of cranial nerves, each with specific functions.
How many pairs of cranial nerves are there?
12 pairs
Each pair is numbered based on its position from anterior to posterior.
What is the function of the Olfactory nerve?
Sensory: responsible for the sense of smell.
It is the first cranial nerve (CN I).
What is the function of the Optic nerve?
Sensory: responsible for vision.
It is the second cranial nerve (CN II).
What is the function of the Oculomotor nerve?
Motor: controls most eye movements, pupil constriction, and maintains an open eyelid.
It is the third cranial nerve (CN III).
What is the function of the Trochlear nerve?
Motor: innervates the superior oblique muscle, which controls downward and lateral eye movement.
It is the fourth cranial nerve (CN IV).
What is the function of the Trigeminal nerve?
Both sensory and motor: responsible for facial sensation and mastication (chewing).
It is the fifth cranial nerve (CN V) and has three branches.
What are the three branches of the Trigeminal nerve?
- Ophthalmic (V1)
- Maxillary (V2)
- Mandibular (V3)
Each branch serves different regions of the face.
What is the function of the Abducens nerve?
Motor: controls lateral eye movement.
It is the sixth cranial nerve (CN VI).
What is the function of the Facial nerve?
Both sensory and motor: responsible for facial expressions, taste sensations from the anterior two-thirds of the tongue, and some functions of the salivary glands.
It is the seventh cranial nerve (CN VII).
What is the function of the Vestibulocochlear nerve?
Sensory: responsible for hearing and balance.
It is the eighth cranial nerve (CN VIII).
What is the function of the Glossopharyngeal nerve?
Both sensory and motor: involved in taste from the posterior one-third of the tongue and innervates part of the pharynx for swallowing.
It is the ninth cranial nerve (CN IX).
What is the function of the Vagus nerve?
Both sensory and motor: regulates heart rate, gastrointestinal peristalsis, and sweating; involved in speech and swallowing.
It is the tenth cranial nerve (CN X).
What is the function of the Accessory nerve?
Motor: controls the sternocleidomastoid and trapezius muscles, aiding in head movement and shoulder elevation.
It is the eleventh cranial nerve (CN XI).
What is the function of the Hypoglossal nerve?
Motor: controls tongue movements for speech and swallowing.
It is the twelfth cranial nerve (CN XII).
True or False: Cranial nerves are exclusively sensory.
False
Cranial nerves can be sensory, motor, or both.
Fill in the blank: The _______ nerve is responsible for the sense of smell.
Olfactory
It is the first cranial nerve (CN I).
Fill in the blank: The _______ nerve innervates the superior oblique muscle.
Trochlear
It is the fourth cranial nerve (CN IV).
What artery supplies blood to the anterior and middle cerebral arteries?
Internal carotid artery
The internal carotid artery is a major supplier of blood to the brain.
What large vessel is formed by the union of the two vertebral arteries?
Basilar artery
The basilar artery supplies blood to the posterior circulation of the brain.
What large arteries are formed by the bifurcation of the common carotid artery?
External carotid artery and internal carotid artery
These arteries supply blood to different regions of the head and neck.
What arteries account for most of the blood supply to the brain?
The two internal carotids account for 85% of cerebral blood flow
This significant flow highlights their importance in brain perfusion.
The middle cerebral artery supplies what areas of the brain?
The insula, most of the lateral surface of the cerebral hemisphere, and the anterior tip of the temporal lobe
This artery is critical for motor and sensory functions.
The anterior cerebral artery supplies to what areas of the brain?
The frontal lobes and medial aspects of the parietal and occipital lobes
It is involved in functions related to decision-making and sensory processing.
The posterior cerebral artery supplies what areas of the brain?
The rostral midbrain, posterior thalamus, medial occipital lobe, and inferior and medial surface of the temporal lobe
This artery plays a key role in visual processing.
Where does the vertebral artery enter the skull?
Foramen magnum
The vertebral artery ascends along the medulla after entering the skull.
Name the arteries that form the circle of Willis.
Parts of the internal carotid artery, anterior and posterior cerebral arteries, interconnected by the anterior and posterior communicating arteries
The circle of Willis provides collateral circulation to the brain.
What structure makes collateral circulation to the brain possible due to vascular anastomosis at the base of the brain?
Circle of Willis
It is crucial for maintaining cerebral blood flow in case of occlusion.
What is an Excitatory Postsynaptic Potential (EPSP)?
A depolarized graded potential that moves the membrane potential toward the threshold and excites the neuron.
EPSPs are crucial for neuronal communication and can influence action potential generation.
What determines the effect of a chemical signal binding to the postsynaptic membrane?
The effect is determined by whether the information will depolarize or hyperpolarize the membrane.
This process is essential in synaptic transmission and influences neuronal excitability.
What does EEG stand for?
Electroencephalography
EEG is a method used to record electrical activity in the brain.
What is recorded in an EEG signal?
Cortically summated excitatory & inhibitory postsynaptic potentials of pyramidal cells
Pyramidal cells are a type of neuron found in the brain’s cortex.
What orientation do pyramidal cells have in relation to the scalp surface?
Oriented at right angles to the plane of the scalp surface
This orientation is crucial for the effective recording of EEG signals.
What is Volume Conduction in the context of EEG?
Current flowing between the electrical generator and recording electrodes through scalp, skull & brain
Volume conduction affects how signals are recorded and can influence the interpretation of EEG data.
What is the Absolute Refractory Period?
Time while the action potential is occurring when the neuron cannot respond to another stimulus no matter how great the stimulus.
What is an Excitatory Postsynaptic Potential (EPSP)?
A depolarized graded potential that drives the membrane potential TOWARDS the threshold and EXCITES the neuron.
What is hyperpolarization?
Increase in the negative charge inside the neuron by the flow of positively charged ions, like K+ outside of the neuron (efflux) or flow of negatively charged ions into the neuron (influx).
What is the typical change in membrane potential during hyperpolarization?
-65 to -70
What is the resting membrane potential of a neuron?
-65 mV to -70 mV
The resting membrane potential indicates that the neuron is not generating an action potential.
What type of charge is present outside of the cell membrane at rest?
Positive (+) Charge
This positive charge contributes to the overall polarization of the neuron.
What type of charge is present inside of the cell membrane at rest?
Negative (-) Charge
The negative charge inside the neuron is crucial for maintaining the resting membrane potential.
True or False: The resting membrane potential indicates that a neuron is actively generating an action potential.
False
The resting membrane potential signifies that the neuron is at rest and not firing.
What is the resting membrane potential of a neuron?
-65 mV to -70 mV
The resting membrane potential indicates that the neuron is not generating an action potential.
What type of charge is present outside of the cell membrane at rest?
Positive (+) Charge
This positive charge contributes to the overall polarization of the neuron.
What type of charge is present inside of the cell membrane at rest?
Negative (-) Charge
The negative charge inside the neuron is crucial for maintaining the resting membrane potential.
True or False: The resting membrane potential indicates that a neuron is actively generating an action potential.
False
The resting membrane potential signifies that the neuron is at rest and not firing.
What is the All-or-None Principle?
Neurons are sufficiently stimulated to produce an action potential or not stimulated enough.
There is no partial firing of neurons.
What is the primary function of neurons?
The brain collects and processes information coming from inside & outside the body & then issues commands by means of neurons
Neurons are essential for communication within the nervous system.
Approximately how many neurons are in the human brain?
100 billion
This number indicates the complexity of the human brain’s neural network.
What is the soma or cell body of a neuron?
The part of the neuron that contains the nucleus and organelles.
How many dendrites can a neuron have?
Thousands.
What is the function of dendrites?
Receive information from other neurons.
How many axons are typically found in a neuron?
Usually only 1.
What is the primary function of the axon?
Send information to other neurons.
What is an Action Potential?
A rapid rise and fall in membrane potential that occurs when a neuron sends an electrical signal.
Action potentials are essential for the transmission of signals in the nervous system.
What are Telodendria?
Several filaments of an axon at its terminal point.
Telodendria play a crucial role in transmitting signals to other neurons.
What is a Bouton (synaptic knob)?
The distal end of each filament of an axon.
Boutons are involved in the release of neurotransmitters.
What do vesicles contain?
Neurotransmitter.
These vesicles release their contents into the synaptic cleft during neurotransmission.
What is the role of a Neurotransmitter?
Converts the electrical signal into a chemical signal.
Neurotransmitters are essential for communication between neurons.
