Brain and Cranial Nerves Flashcards
typical characteristics of the brain
-97% of the bodys nervous tissue
-weight is around 3lb
-volume around 1200mL
-brains of males larger than females
regions of the brain
-cerebrum
-cerebellum
-diencephalon
-brainstem
cerebrum
-largest part of the adult brain
-controls higher mental functions like conscious thought, intellect, memory
-divided into left and right cerebral hemispheres
-conscious and subsconcious regulation of skeletal muscle contractions
-gray matter in cerebral cortex and basal nuceli
and white matter is deep to cerebral cortex around basal nuceli
cerebral cortex
-surface layer of gray matter
-rounded elevates called gyry increase surface area
-gyri are seperated by shallow depressions (sulci) or deep grooves (fissures)
cerebellum
-coordinates complex somatic motor patterns
-adjusts output of other somatic motor centers in brain and spinal cord
-second largest part of the brain
-coordinates repetitive body movements
-two hemispheres
-covered by gray matter
diencephalon
-thalamus and hypothalamus
thalamus
relays and processes sensory information
hypothalamus
controls emotions, autonomic functions and hormone production
brainstem
-midbrain
-pons
-medulla oblangata
midbrain
-processes bisual and autory data
-generates reflexive somatic motor responses
-maintains consciousness
pons
-relays sensory information to cerebellum and thalamus
-subconscious somatic and visceral motor centers
medulla oblongata
-relays sensory information to thalamus and other portions of the brainstem
-autonomic centers for regulation of visceral function
-most inferior part
-3 groups of nuclei that control visceral functions, sensory and motor nuclei of CNS and relay stations for communication between brain and spinal cord
origins of the brain structure
-telencephalon –> forms cerebrum
-metencephalon –> forms cerebellum and pons
-myelencephalo –> forms medulla oblongata
ventricle system of the brain
-lateral ventricles
-interventricular foramen
-third ventricle
-cerebral aqueduct
-fourth ventricle
brain protection and support
-physical protection through bones, meninges, CSF
-biochemical isolation through BBB
cranial meninges
-3 layers - dura mater, arachnoid mater, pia mater
-continous with spinal meninges
CSF
-surrounds all exposed surfaces
-supports brain
-cushion delicate nueral structures
-trasnport nutrients chemical messengers and wastes
flow of the CSF
-from choroid plexus through ventricles and fills the central canal of the SC
-CSF reaches subarachanoid space through two lateral apertures and a single median aperture in the rood of the fourth ventricle
-CSF then flows through subarachanoid space surrounding the brain spinal cord and cauda equina
choroid plexus
-produces CSF
-specialized ependymal cells surround capillaries
-secretes about 500mL of CSF into ventricles per day
-removes wast eproducts from CSF
-adjust composition of CSF
how is CSf absorbed into the venous circulation
-through fingerlike extensions of the arachanoid membrane called arachnoid villi
-the villi produces large arachanoid granulations which CSF is absorbed through
protective function of meninges
-dural folds hold brain in position
CSF cushions brain against sudden jold
cranial trauma
-head injury resulting from impact with an object
blood supply to brain
-internal carotid artieries and vertebral arters deliver oxygen and nutrients
-most blood removed from dural venous sinuses by internal jugular veins
cerebrovascular diseases
-diseases that interfere with blood supply to brain
-Cerebrovascular accident or stroke stops blood flow to the brain and affected nuerons begin to die within minutes
blood brain barrier
-isolates CNS fro general circulation
-network of tight junctions between capillary endothelial cells in CNS
-only lipid soluble compounds can diffuse across
-astrocytes regulate BBB by releasing chemicals that control permeability of endothelium
blood CSF barrier
-formed by specialized ependymal cells connected by tight junctions
-limit tranfer of substances to CSF
-allows chemical composition of blood and CSF to differ
breaks in BBB
-portions of the hypothalamus allows hypothalmic horomones into circulation
-poserior lobe of pituitary gland allows aADH and ocytocin into circulation
-pineal gland - allows pineal secretions into circulation
-choroid plexus where specialized ependymal cells maintain blood CSF barrier
reticular formation
-contain nuceli and centers that regulate autonomic functions and extends into the pons and midbrain
Pons contains
-sensory and motor nuclei of cranial nerves
-nuceli involved with respiration
-nuclei and traxts that process and relay information sent to or from cerebellum
-ascending, descending and transverse pontine fibres
transverse pontine fibres
-link nucli of pons with opposite cerebellar hemisphere
structures of the midbrain
-tectum
-tegmentum
-cerebral peduncles
cerebellar cortex
-involuntary cooridnation and control of ongoing body movements
-involuntary
cerebellar nuceli
-involuntary coordination and control of ongoing body movements
diencephalon function
-integrates sensory information with motor commands
-epithalamus, thalamus, hypothalamus
thalamus
-filters and relays sensory info from spinal cord and CN to cerebral cortex
-relays inforbation between basal nuclei and cerebral cortext
-the third ventricle seperates left and right sides
-interthalamic adhesion
five groups of thalamic nuclei
-anterior nuclei of thalamus (emotions)
-medial. nuceli of thalamas (awareness of emotional state)
-ventral nuclei of thalamus (senory info to cerebral cortex)
-dorsal nuceli of thalamus (sensory)
-geniculate bodies (visual and auditory)
strucutre of the hypothalamus
-mamillary bodies - control relfex
-infundibulum - narrow stalk that connects hypothalamus to pit. gland
-tuber cinereum - hormone that affects the pit. gland
eight functions of hypothalamus
0secretes ADH and oxytocin
-regulate body temp
-control autonomic function
-coordinate voluntary and autonomic function
-coordinates nervous and endocrine system
-regulate circadian rhythm
-subconcious control of skeletal muscle
-produce emotion and behavioural drives
limbic system
-establishes emotional states
-links conscious function of cerebral cortex witha utonomic functions of the brainstem
-facilitates memory storage and retrieval
function of basal nuceli
-subconscious control of skeletal muscle tone
-coordination of learned movement patterns
-parkinsons- symptoms caused by increased activity of basal nuceli
cortex of each cerebral hemisphere
-recieves somsatosensory information from and sends motor commands to the opposite sides of the body
primary motor cortex
-voluntary control of skeletal muscle
primary somatosensory cortex
-perception of touch, pressure pain vibration taste and temperature
visual cortex
0conscious perception of visual stimuli
auditory cortex and olfactory cortex
-conscious perception of auditory and olfactory stimuli
motor, sensory, somatosensory and assoication areas
-integration and processing of sensory data
-processing and initaition of motor activitie
integrative centers
-in lobes and cortical areas of both cerebral hemispheres
-recieve information from association areas
-direct complex motor activities
-perform analytical functions
brocas area
-speech production
-breathing and vocalization
wernickes area
-language comprehension
hemispheric lateralization
-functional differences between left and right cerebral hemispheres
-each performs certainf ucntions that are not ordinarily performed by the opposite hemisphere
left cerebral hemisphere
-reading writifn and math
-speech language
-decision making
right cerebral hemisphere
-analyzes sensory info
-recognition of faces and voice inflections
how to assess brain activity
-electroencephalogram
-electrodes are placed on brain or skull
-electrical patterns/brain waves are obsevred
types of waves: alpha waves, beta waves, theta waves, delta waves
classification of cranial nerves
-primarily sensory - carriers of somatic sensory information
-special sensory - carriers of senstations
-motor: axons of somatic motor nuerons
-mixed:sensory and motor fibres
cranial nerves are classified by
primary function but also have important secondary function
olfactory nerve
CN I
-smell
-comes from receptors of olfactory epithelium
-goes to olfactory bulbs
optic nerve
CN II
-special sensory - vision
-retina of eye to diencephalon via optic chiasm
Oculomotor nerve
CN III
-eye movement (motor)
-from midbrain
trochlear nerves
-CN IV (4)
-eye movement
-from midbrain to superior obliquea
abductens nerve
CN VI (6)
-eye movement (motor)
-from pons to lateral rectus
trigeminal nerve
CN V (5)
-mixed - sensory and motor of face
-three branches
-V1 = opthalamic nerve
-V2 = maxillary nerve
-V3 = mandibular nerve
Facial nerve
CN VII
-mixed sensory and motor of face
bells palsy
-cranial nerve disroder resulting from inflammation of facial nerve
-likely viral infection
-paralysis of facial muscles on affected side
-loss of taste sensations from anterior two thirds or tongie
-symptoms fade after weeks or months
vesibulocochlear nerve
CN VIII
-special sensory
-balance and equilibirum
glossopharyngeal nerve
CN IX
-mixed function of head and neck
vagus nerve
CN X
-mixed function
widely distrbuted
in thorax
accessory nerve
CN XI
-motor to muscle of neck and upper back
hypoglossal nerves
CN XII
-tongue movement
cranial reflexes
-monosynaptic and polysynaptic relfex arc
-involve sensory and motor fibers of cranial nerves
-clinically useful to check condition of cranial nerves and parts of the brain
