Chapter 15 - Brain and Cranial Nerves Flashcards
Meninges are similar in what structures?
Brain and spinal cord
Regions of the brain
- Cerebrum
- Diencephalon
- Mesencephalon
- Cerebellum
- Pons
- Medulla Oblangata
- Outer most layer of the brain
- No epidura
Dura Mater
What does the dura mater form?
Forms internal periosteum of skull
Dura mater partitions
- Falx cerebelli
- Falx cerebi
- Tentorium cerebelli
Separates right and left cerebellar hemispheres
Falx carebrelli
Separates right and left cerebral hemispheres
Falx cerebri
Separates lobes of cerebrum from cerebellum
Tentorium cerebelli
- Spidery
- Spreads over brain but doesn’t extend into grooves and depressions
Arachnoid Mater
- Inner most
- Aids in nourishing the brain
- Attached to the surface of the brain
Pia mater
Spaces filled with CSF
Ventricles
Different kinds of ventricles in the brain
- 2 lateral ventricles
- 3rd ventricle
- 4th ventricle
Ventricles and things that connect them
- 2 lateral ventricles connected by interventricular foramen to…
- 3rd ventricles which is connected by the cerebral aqueduct to…
- 4th ventricle connected to central canal of spinal cord
Functions of Cerebrospinal Fluid
- Cushions
- Transports nutrients, wastes, and other chemicals
- Supports the brain
- Lobes located in the ventricles
Choroid plexus
What does the choroid plexus consist of?
- Ependymal cells
- Permeable capillaries
What does the choroid plexus do?
CSF is taken from blood by ependymal cells and pooled in ventricles
Where does CSF move in the CNS?
All throughout the entire CNS
Explain the movement of CSF throughout the CNS
- Originates in ventricles
- Through aperatures in the 4th ventricles to subarachnoic space
- Throughout the central canal
- Around subarachnoid space
Where does the CSF get absorbed?
Sagittal sinus
Describe CSF being reabsorbed
- A large venous tube within the dura mater
- Extends along the midline of the cerebral hemispheres
- Arachnoid extends into sinus through ARACHNOID GRANULATIONS
- CSF goes back to the blood
Functions of the cerebrum
- Interpret sensory impulses
- Voluntary muscular movements
- Memory
- Reasoning process
- Intelligence and personality
The two hemispheres are connected by what?
Corpus callosum
What are the two hemispheres separated by?
Longitudinal fissures
Ridges and grooves of cerebrum
Ridges = gyri Grooves = sulci
What is hemisphere specialization?
Receives sensory and generates motor information to the opposite sides of the body
Communication between the hemispheres allowed for by _____
Corpus callosum
Gray matter is essentially what?
Cell somas
Where is the cell somas (grey matter)
Outer regions of cerebral lobes
Cell somas (grey matter) is centralized in masses called what?
Basal nuclei
Myelinated axons are what?
Cerebral white matter
Components to cerebral white matter
- Commissural fibers
- Association fibers
- Projection fibers
Connect corresponding gray areas on different hemispheres
Commissural fibers
Connect different parts of same hemisphere
Association fibers
Connect cerebrum to lower brain areas
Projection fibers
Cerebral lobes
Frontal Parietal Temporal Occipital Insula
Lobes are divided by what?
Special sulci
Three sulci that divide lobes?
Central sulcus
Lateral sulcus
Parieto-occipital sulcus
Separates the frontal lobe from the parietal lobe
Central sulcus
Separates the parietal lobe from the temporal
Lateral sulcus
Separates the parietal lobe from the occipital
Parieto-occipital sulcus
Where is the primary motor cortex?
Anterior to central sulcus in frontal lobe
What does the primary motor cortex do?
- Conscious control of skeletal muscles
- Learned motor skills
- Speech and eye movements
Where is the primary sensory cortex?
Posterior to central sulcus on parietal lobe
In the primary sensory cortex, somatic sensory information comes from what?
Touch, pain, pressure
What does the primary sensory cortex monitor?
Monitor the environment consciously
Other sensory cortexes
Visual cortex
Auditory cortex
Olfactory cortex
Gustatory cortex
Location and function of visual cortex
Occipital lobe
Sight
Location and function of auditory cortex
- Temporal lobe
- Sound
Location and function of olfactory cortex
- Temporal lobe
- Smell
Location and function of Gustatory Cortex
- Insula and frontal lobe
- Taste
Association areas are associated with what large motor or sensory cortexes
- Somatic sensory
- Somatic motor
- Visual
- Auditory
What is the prefrontal cortex?
- Abstract intellectual function
- Predictions, problem solving
- Emotional context and motivation
- Timing and temporal relationships
What is the removal of the prefrontal cortex?
Pre-frontal lobotomy
Regulates breathing and vocalization
Broca’s speech center
- Interpretation of both written and verbal language
- Sentence structure and word linkage
General interpretive area
Damage of Broca’s speech center or General Interpretive Area results in what?
Aphasia
Higher order integrative regions may be different between hemispheres
Hemisphere Dominance
Speech, writing, and general interpretive area
Categorical hemispheres
- Identification of familiar objects
- Touch and spatial analysis
- Emotional relevance
Representational hemisphere
Right handed people tend to have their categorical hemispheres on the _____, and vice versa
Left
Masses of gray matter deep in cerebral hemisphere
Basal Nuclei
What does the basal nuclei do?
Act as relay station for motor impulses starting in cerebral cortex and passing to brain stem and spinal cord
- In basal nuclei
- Focuses visual attention
- Processes unconscious visual info
Claustrum
- In basal nuclei
- Controls and adjusts muscle tone
Lentiform nucleus
- In basal nuclei
- Massive head, slender tail
- Maintains pattern and rhythm of movement
Caudate nucleus
- In basal nuclei
- Tip of caudate tail
- Part of limbic system
Amygdaloid nucleus
Components to the diencephalon
- Epithalamus
- Posterior pituitary gland
- Hypothalamus
- Thalamus
What is in the epithalamus?
Pineal gland = produces melatonin
Two major bodies of the thalamus
- Divided by the third ventricle
- Connected by an interthalamic adhesion
Three major functions of the thalamus
- Part of the limbic system
- Connect basal nuclei and cerebral cortex
- Sends sensory information to proper location within cerebrum
How does the Thalamus function as part of the limbic system?
- Emotional, memory, learning
- Conscious awareness of emotion
How does the thalamus connect basal nuclei and cerebral cortex?
- To each other
- To other parts of the CNS
Above and connected to the posterior pituitary gland
Hypothalamus
Functions of the hypothalamus
- SUBCONSCIOUS control of skeletal muscles
- Coordinates autonomic nervous system
- Connection between the endocrine and nervous system
- Produces hormones
- Produces BEHAVIORAL DRIVES
- Regulates body temp
- Controls circadian rhythms (sleep)
- Connects brain stem and spinal cord with higher areas
- Act as relay centers
Mesencephalon (midbrain)
Contain _____ that connects third and fourth ventricles
Cerebral aqueducts
Parts of the mesencephalon
- Cerebral peduncles
- Red nucleus
- Substantia nigra
- Corpora quadrigemina
- Only connecting fibers and no nuclei
- Motor fibers connecting the cortex to the spinal cord
- Sensory fibers that synapse with the thalamus
Cerebral peduncles
- Highly vascularized
- Connects cerebrum and cerebellum
Red nucleus
What does the red nucleus control?
- Posture
- Reflexes
- Controls and integrates the motor output of the basal nuclei
Substantia nigra
What does the substantia nigra produce?
Dopamine (giving it a black color)
Deterioration of the substantia nigra may lead to what?
Parkinson’s disease
Parkinson’s disease results in what?
Loss of control of voluntary motor function
Two components to the Corpora Quadrigemina with their meanings?
- Superior colliculi - Receives visual input from thalamus
- Inferior colliculi - Receives auditory input from medulla
Rounded bulge on underside of brain stem?
Pons
What does the pons separate?
Midbrain from medulla
What do the pons do?
Relays impulses to and from medulla cerebrum
- Regulates depth of breathing
What is the pons composed of?
Masses of gray matter and nerve fibers
The cerebellum has to regions separated by the ______ and connected by the ______
- Falx cerebelli
- Vermis
The cerebellum is composed mostly of what?
White matter which is called the arbor vitae
Functions of the cerebellum
- Integrates sensory information about the position of body parts
- Coordinates muscle activities
- Maintain posture
- Fine tunes voluntary and involuntary movements
Where is the medulla oblongata?
From the foramen magnum to pons
A point of connection for several cranial nerves
Medulla oblongata
Oval swelling in the medulla oblangata
Olivary nucleus
Reflex centers in the medulla oblongata?
- Cardiovascular center
- Respiratory rhythmicity center
Part of the medulla oblongata that adjusts blood flow and heart rate
Cardiovascular center
Basic pace of respiratory movements in the medulla oblongata
Respiratory rhythmicity center
Network of nerve fibers associated with islands of gray matter
Reticular formation
What does the reticular formation interconnect?
Interconnects areas with fibers in all major tracts
What does the reticular formation regulate?
Motor activities
(Increase activities –> wakefulness)
(Decrease activity –> sleep)
What is the limbic system composed of?
Nuclei and tracts along the boarder cerebrum and diencephalon
Parts of the limbic system in the cerebrum
- Limbic lobe - deep to all other lobes
- Hippocampus - nucleus within the lobe
- Amydaloid body - basal nucleus
Parts of the limbic system in the diencephalon
Thalamus - relay center
Hypothalamus - behavioral drive center
Parts of the limbic system in the medulla
Reticular formation - sleep and wakefulness
Functions of the limbic system
- Establishes emotional states and related behavioral drives
- Links intellectual functions of cortex to unconscious functions of lower brain
- Facilitates memory storage
How many cranial nerves are there?
12
Where do the cranial nerves originate from?
Brain stem except for the first pair
Where do all the cranial nerves pass through?
Foramina in skull
- In cranial nerves, cell bodies for motor are found where?
Gray matter
In cranial nerves, cell bodies for sensory found in ganglia where?
Outside of the brain
Three facts about why cranial nerves are messy
- May look disorganized in mammals
- Are organized sequentially in fish and cephalochordates
- This is evidenced in a fetus as well
Facts about the olfactory nerve
- I
- Sensory
- Smell
- Pass through cribiform plate
Facts about optic nerve
- II
- Sensory
- Vision
- Pass through optic foramina
Facts about oculomotor nerve
- III
- Motor
- Move the majority of eye muscles
Facts about Trochlear Nerve
- IV
- Motor
- Smallest pair
- Superior oblique muscles of eye only
Facts about trigeminal nerve
- V
- Both
- Largest
- 3 branches
Three branches of the Trigeminal nerve
- Eye, tear gland, skin of anterior scalp, forehead and upper eyelid
- Upper teeth, gum, lip, mucous lining of palate, and skin of face
- Scalp, skin of jaw, lower teeth, gum, lips, muscles of mastication
Facts about Acducens muscle
- VI
- Motor
- From pons
- Lateral rectus eye muscles only
Facts about the facial nerve
- VII
- Both
- From pons
- Sensory: taste receptors on ant. 2/3 of tongue
- Motor: to muscles of facial expression; stimulate tear and salivary glands
Facts about Vestibulocochlear nerve
- VIII
- Sensory
- Auditory nerve from medulla
- Two parts
Two parts of the vestibulocochlear
- Sensitive to changes in position of head
- Interpreted as hearing
Facts about the glossopharyngeal nerve
- IX
- Both
- Sensory: form lining of pharynx, tonsils and post 1/3 of tongue
- Motor: to wall of pharynx to help swallowing
Facts about the Vagus
- X
- Both
- From medulla to chest and abdomen (innervates GUT)
- Sensory from lining of pharynx, larynx, and esophagus and abdomen
- Somatic motor: to muscles of larynx –> speech and swallowing
- Autonomic motor: to heart, other smooth muscles and glands in visceral organs
Functions of accessory nerves
- XI
- Motor
- 2 branches
Two branches of the accessory nerve
Cranial: from medulla to muscles of soft palate, pharynx and larynx
Spinal: sends motor fibers to trapezius and sternomastocleoid
Characteristics of the hypoglossal nerve
- XII
- Motor
- From medulla to tongue
- For speaking, chewing, and swallowing