A&P 1: Lower Brain/Cerebrum/CNs Flashcards
What are the 4 parts of the diencephalon?
Thalamus
Hypothalamus
Epithalamus
Subthalamus
What supports the largest part of the brain?
Diencephalon and brain stem support the cerebrum
What are the two layers of the cranial dura mater?
What makes these layers?
External periosteal- formed by periosteum covering the internal surface of the cranium
Internal meningeal- continuous w/ dura mater of the spinal cord
The two layers of the cranial dura mater are fused together except for where?
Separate to enclose the dural venous sinuses
What is the function of the dural venous sinuses?
Drain blood from brain to the internal jugular vein
What are the 3 extensions of the dura mater?
Falx cerbri- cerebrum hemispheres
Falx cerebelli- cerebellum hemispheres
Tentorium cerebelli- cerebrum and cerebellum
Brain consumed __% of the body’s O2 and glucose
20%
Neurons synthesize ATP almost exclusively from ____
Glucose
What are the parts of the brain that lack the BBB?
Pineal gland
Pituitary gland
Medial eminence of hypothalamus
What part of the brain senses toxins in the blood and is responsible for control over vomiting?
Area postrema (4th ventricle)
What can pass into the BBB by active transport?
Water soluble
Glucose
What crosses the BBB very slowly?
Not at all?
Easily?
Slowly: Creatinine, urea, ions
Not: proteins, ABX
Easily: O, CO2, ETOH, anesthetics
What space does CSF circulate through?
Subarachnoid space
What separates the lateral ventricles?
Septum pellucidum
What surrounds the 3rd ventricle?
R/L halves of thalamus
What surrounds the 4th ventricle?
Brain stem
Cerebellum
Where is the CSF made and by what type of cells?
Produced in choroid plexuses by ependymal cells
How do ependymal cells make CSF?
By filtration (some secretion)
What is the sequence of CSF flow from lateral ventricles -> circulation?
Lateral ventricles Interventricular foramina 3rd ventricle Aqueduct 4th ventricle Median (1) and lateral (2) apertures Subarachnoid space
How can hydrocephalus develop in adults?
Head trauma
Meningitis
Subarachnoid hemorrhage
Define reticular formation
Gray and white matter network that spans throughout brain stem
What processes/reflexes does the medulla oblongata control?
Breathing
HR
BP
Cough
Swallow
Vomit
Where does the medulla oblongata start?
Foramen magnum
What color matter is found in the medulla oblongata?
White w/ ascending and descending tracts
Define pyramids and their functions
Bulges of white matter on ANTERIOR Corticospinal tracts (largest motor tracts from cerebrum->spine)
Define decussation and where it occurs?
Axons of L pyramid cross to R side of pyramid
Medullary nuceli are what color matter?
Gray
What are the 3 masses in the medullary nuclei
Cardiovascular
Medullary rhythmic
Deglutition
What is the function of the cardiovascular center?
Heart rate and force
Vessel diameter
What is the function of the medullary rhythmic center?
Adjusts basic rhythm of breathing
Function of the inferior olivary nucleus
Relay impulses from cortex, red nucleus and spinal proprioceptors to cerebellum
What nucleus’ make up the posterior nuclei?
Gracile and cuneate nucleus
What are the functions of gracile and cuneate nucleus
Touch
Conscious proprioception
Pressure
Vibration
Where are the first and second order sensory neurons and where do the relay impulses to?
First order- bodies in dorsal root of spinal cord
Second order- bodies in correspondingly named posterior nucleus of medulla
First order->posterior columns->Posterior nuclei->second order->medial lemnisus in thalamus
What is the name of the white band in the thalamus?
Medial lemniscus
The medial lemniscus extends through what 3 structures?
Medulla
Pons
Midbrain
Define posterior column-medial lemniscus pathway?
Tracts of posterior columns +
Axons of medial lemniscus
Where do pontine nuclei relays signals to? What type of signals are these?
Voluntary muscle movements from cortex->cerebellum
What are the two structures in the pontine that help control breathing?
Pneumotaxic center
Apneustic area
What are the components of the respiratory center?
Medulla- rhythmic
Pons- pneumotaxic
Pons- apneustic
What are the two parts of the medullary rhythmic area?
Inspiratory and expiratory area
What happens when the inspiratory center is active?
Generates nerve impulses to: EXTERNAL intercostal muscles
diaphragm
During normal, quiet breathing and in the absence of the inspiratory center, what event occurs?
Exhalation, passive recoil of lungs and thoracic wall
What center is inactive during quiet breathing?
Expiratory
What happens with the expiratory center during forceful breathing?
Expiratory area sends impulses to INTERNAL intercostal and abdominal muscles
What contribution does the pneumotaxic and apneustic area make during respiration?
Pneumotaxic- turn inspiratory area off (prevents over expansion)
Apneustic- prolongs inhalation by sending impulses to inspiratory area
CN 8 has nuclei in what two parts of the brain stem?
Pons
Medulla
What are the two sensory branches of CN8
Vestibular- sensory axon ending in pons
Cochlear- sensory axons ending in medulla
How does the vestibular branch of CN8 enter the cerebellum?
Inferior cerebellar peduncle
What are the motor axons of CN*?
Project from pons to hair cells in semicircular canals and spiral organ
What is the function of the mesencephalon?
Connects the pons to the diencephalon
What types of impulses does the cerebral peduncles conduct?
Corticospinal
Corticobulbar
Corticopontine
What does the tectum contain?
Two rounded elevations, corpora quadrigemina
The Corpora Quadrigemina comprised of what two structures?
Superior colliculi
Inferior colliculi
Function of superior colliculi
Extrinsic eye movement during eye tracking
Pupil reflex
Accommodation reflex
Function of the inferior colliculi
Relays impulses from inner ear to thalamus
Startle reflex
Function of the Substantia Nigra
Releases dopamine
Controls subconscious muscle activities
What structure of the brain is effected by Parkinson’s disease?
Substantia Nigra
Function of the Red Nuclei
Coordinate muscle movements
Why is the Red Nuclei red?
Rich blood supply
Iron containing pigment in neuron cell bodies
Where does the rubropsinal tract originate?
Red nucleus
What does the Red Nucleus control?
Baby crawling
Arm swings during walking
Upper shoulder/arm muscles
What controls the fine/precise movements of fingers?
Corticospinal tract
What is the main function of the Reticular Formation?
Main function: regulates muscle tone
RAS: Maintain consciousness, awakening from sleep
What is the vermis and where is it found?
Central constricted area of the cerebellum
Define folia and where are they found?
Ridges on surface of cerebellum
What are the components of the cerebellar cortex?
Gray matter w/ foliar ridges
White matter forming the arbor vitae
Function of the cerebellar peduncles?
Conduct impulses between cerebellum and brain
Difference between Cerebral Peduncles and Cerebellar Peduncles?
Cerebral: anterior, impulses from cerebrum to spine
Cerebellar: posterior, impulses from cerebellum and brain
Main function of the cerebellum?
Evaluate how well movements are carried out
Posture
Balance
Function of the anterior/posterior lobes of cerebellum?
Unconscious refinements of skeletal muscle movements
Function of the floculonodule lobe of the cerebellum?
Equilibrium and balance
Define ataxia
Without order, incoordination
Ataxia is contributed to what issues in the cerebellum?
Infection
Injury
Disease
Degeneration
How does alcohol effect the brain and potentially cause death?
Inhibits cerebellum
Suppresses medullary rhythmicity
Diencephalon surrounds which brain ventricle?
3rd
Where does the deincephalon extend from/to?
From brain stem to cerebrum
What makes up most of the diencephalon?
Thalamus
What connects the two halves of the thalamus?
Intermediate mass
What are the functions of the thalamus?
Main relay station for sensory impulses
Autonomic activities
Maintenance of consciousness
What is the function of the Internal Capsule?
Band of thick white matter
Separates thalamus and caudate nucleus from lentiform nucleus
Function of the Mammillary bodies?
Relay station for olfactory reflexes
What is the main visceral control center of the body?
Hypothalamus
Hypothalamus receptors monitor what things?
Glucose
Osmotic pressure
Blood temp
Hormones
What are the specific functions of the hypothalamus?
ANS Hormone production Emotion Behavior Eating Drinking Body temp Cardiac rythms States of consciousness
Parts of the epithalamus and their function?
Habenular nuclei- emotional olfactory responses
Pineal gland- melatonin secretion
What does the subthalamus contain?
Tracts
Paired subthalamic nuclei
What are the layers of matter in the cerebral cortex?
Gray->white->gray nuclei
What is the most prominent fissure?
Longitudinal fissure- separates cerebrum into R/L hemispheres
When are gyri and fissures developed?
Embryonic development
When gray matter of cortex enlarges faster than the deeper white matter
Define central sulcus
Separates the frontal and parietal lobes
Define the lateral cerebral sulcus
Separates frontal and temporal lobes
Define parieto-occiptal sulcus
Separates the parietal and occipital lobe
Define association tracts
Nerve impulses between gyri in same hemisphere
Define Commissural tracts
Nerve impulses between gyri across different hemispheres
Define Projection tracts
Nerve impulses from cerebrum to lower CNS / lower CNS to cerebrum
What are the important groups of commissural tracts?
Corpus callosum
Anterior/posterior commissure
What makes up the basal ganglia?
Globus pallidus
Putamen
Caudate nucleus
What makes up the Lentiform nucleus?
Globus Pallidus
Putamen
What makes up the Corpus Striatum?
Lentiform and Caudate nucleus
Why is the Basal Ganglia a naming exception?
Ganglia usually used for collections of nerve cell bodies outside of CNS
What does the basal ganglia help regulate?
Initiation and termination of movements
Control conscious contractions of skeletal muscles
Muscle tone
Define inconscient
Unconscious
What movement disorders affect the basal ganglia?
Parkinsons- melanin-pigmented dopamine producing neurons of basal ganglia degenerate
Huntingtons- damage to corpus striatum
What happens if the basal ganglia is damaged?
Tremors
Stiffness
Involuntary movements
Basal ganglia damage has bee linked back to what disorders?
OCD and ADHD
What is the Limbic system?
Emotional, affective brain
What is the “emotional brain”?
Limbic system
What does the Limbic system play a primary role in regulating?
Pain Pleasure Docility Affection Anger
Where does the Limbic system tie into other brain structures?
Encircle upper part of brain stem
What are the components of the limbic system?
Hippocampus Amygdala Limbic lobe Dentate and Cingulate gyrus Mammillary bodies Anterior/medial thalamus nuclei Olfactory bulbs Fornix
What is the role of hippocampus?
Converting new info->long term memories (autobiographical and factual)
The memory “gateway”
What does the amygdala play roles in?
Docile behavior
Rage
Aggression- presence or absence
Restlessness
What do the olfactory bulbs synapse with?
Olfactory receptors
What are the olfactory relay stations?
Mammillary bodies
What is the location and function of the Cingulate Gyrus?
Superior to Corpus Callosum
Sensory input w/ emotions, regulates aggression and mediates emotional response to pain
What is the function and location of the Fornix?
Extends from hippocampus to mammillary body of hypothalamus
Forms arch over thalamus
Carries signals hippocampus->hypothalamus
Transfers info mammillary bodies->hippocampus
What happens if the hippocampus is damaged?
Anterograde amnesia- inability to generate new memories
What is the “executive suite” of the brain?
Cerbral cortex
What are the functions of the Cerebral Cortex?
Communicate Perceive Remember Understant Appreciate Initiate voluntary movement
What type of matter makes up the Cerebral Cortex?
Gray matter only Neuron bodies, dendrites and unmyelinated axons Glia Vessels NO FIBER TRACTS
What is each hemisphere of the brain mainly concerned with?
Contralateral sensory and motor functions
Generally, there is _____ of cortical function
Lateralization (specialization)
Define association areas
Communicate w/ motor cortex and association areas to analyze, recognize and act on sensory inputs
Receive input from primary’s and integrate sensory experiences to generate patterns of recognition/awareness
Define Primary Sensory Areas?
Receives impulses from sensory neurons w/out prior filtering/analysis
Define Primary Motor area?
Originators of voluntary muscle contractions
What is located in Areas 44/45 of the Frontal Lobe and what function does it have?
Broca’s Speech Area
Planning and production of speech
Nerve impulses->premotor regions
What is located in Areas 22, 39/40?
Wernicke’s Area
Interprets and recognizes spoken words
Define aphasia
Inability to use or comprehend words
What hemisphere contains the language areas?
L hemisphere
What occurs if there is damage to Broca’s Area?
Non-fluent aphasia- inability to form words (know what to say, can’t say it)
What happens if there is damage to Wernicke’s Area?
Fluent aphasia
Produces strings of words w/out combined meaning
People with fluent aphasia may exhibit what two forms?
Word deafness- inability to understand spoken words
Word blindness- inability to understand written words
Or, both
What functions are predominantly controlled by the LEFT hemisphere?
Language
Math
Logic
What functions are predominantly controlled by the RIGHT hemisphere?
Visual-spatial skills
Intuition
Emotion
Art/music appreciation
Define hemispheric lateralization
Functional asymmetry between the brain hemispheres
What are the suspected causes of Alzheimers
Genetics
Environment
Lifestyle
Aging process
What anatomical changes are found in a brain with Alzheimers upon autopsy?
Loss of neurons that release ACh
Destruction of neurons at nucleus basalis
Beta-amyloid plaques
Neurofibrillary tangles
What is the hallmark sign/finding of Alzheimers in a brain?
Neuron destruction at nucleus basalis
Define concussion
Brain injury w/ loss of consciousness
Vision disturbances
Issue w/ equilibrium
THE MOST COMMON BRAIN INJURY
Define contusion
Bruising of the brain due to trauma (concussion)
Define Free Radical
Charged molecule w/ unpaired ve-
Define hematoma
Localized, clotted pool of blood
Define ischemia
Reduction of blood flow
Define laceration
Tear of the brain, rupture of large vessels
Define cerebrovascular accident
Stroke
Usually caused by intercerebral hemorrhage, emboli or atherosclerosis of cerebral arteries
Define Transient Ischemic Attack
Impaired brain blood flow causing episode of temporary cerebral dysfunction
Define agnosia
Inability to recognize significance of sensory stimuli (sounds, sights, smells)
Define apraxia
Inability to carry out movements in absence of paralysis
Define lethargy
Functional sluggishness
Define Reye’s Syndrome
Effects brain and liver after viral infection (chicken pox, influenza)
Most often in kids/teens who take aspirin
Define stupor
Unresponsiveness that can be aroused for brief moments w/ vigorous stimulation
What are the only two “only” sensory neurons?
1 and 2
What are nerves are grouped as the sensory nerves?
1 2 8
What nerves are grouped together as motor nerves?
3 4 6 11 12
What is the sensory function of the primary motor nerves?
Proprioception
What nerves are termed as “mixed” nerves?
5 7 9 10
What two CNs only innervate one muscle?
4- superior oblique
6- lateral rectus
Which motor neurons also have autonomic axons?
3 7 9 10
Motor neurons w/ autonomic nerves are part of what branch of NS?
What do they innervate?
Parasympathetic
Innervate glands, smooth muscle and cardiac muscle
What type of neurons are olfactory receptors and optic nerves?
Bipolar
How do olfactory axon bundles form olfactory nerves?
Extend through cribiform plate of ethmoid bone