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12 cranial nerves
I. Olfactory II. Optic III. Oculomotor IV. Trochlear V. Trigeminal VI. Abducens VII. Facial VIII. Vestibulocochlear IX. Glossopharyngeal X. Vagus XI. Assesory XII. Hypoglossal
Type of nerves
1. sensory 2. sensory 3. motor 4. motor 5. both 6. motor 7. both 8. sensory 9. both 10. both 11. motor 12. motor
holes they intervate
1. Olfactory Foramina 2. Optic Foramen 3. Superior Oribital Fissure 4. Superior Orbital Fissure 5. Foramen Ovale, Superior Oribital Fissure, Foramen Rotundum 6. Superior Orbital Fissure 7. Stylomastoid Foramen 8. Internal Auditory Meatus 9. Jugular Foramen 10. Jugular Foramen 11. Jugular Foramen 12. Hypoglossal Canal
Origin of cranial nerves
1. from olfactory mucosa 2. from retina of eyeball 3. originates in midbrain 4. originates in midbrain 5. originates in end of pons 6. originates in pons 7. originates in end of pons 8. from spiral organ in cochlea & semicircular canals, saccule & utricle in vestibule 9. originates in medulla, arises from taste buds or carotid sinus 10. originates or ends in medulla 11. cranial portion originates in medulla, spinal portion comes from cervical vertebrae 12. originates in medulla
function of cranial nerves
1. smell 2. sight 3. movement of eyeball (superior, medial, & inferior rectus & inferior oblique) & eyelid accommodation of lens & constriction of pupil 4. movement of eyeball ( superior oblique) 5. chewing, major sensory nerve of face, divides into 3 branches that provide sensations for touch, pain, & temperature for the face 6. movement of eyeball ( lateral rectus) 7. facial expression & sevretion of saliva, tears, & taste. 8. hearing & equilibrium 9. secretion of saliva. taste & regulation of blood pressure 10. cardiac & smooth muscle control & controls secretion of digeative fluids (parasympathetic) sensation from visceral organs. 11. swallowing & movement of head 12. movement of tongue
central nervous system
°brain & spinal cord ° rostral: toward the nose ° caudal: toward the tail
function of spinal cord
• spinal nerves attach to it • provides two- way conduction pathway • major center for reflexes ~location of spinal cord • runs through the vertebral canal • extends from foramen magnum to the level if the vertebra L1 or L2
Spinal Cord Terms
• Conus medullaris: inferior end of spinal cord • Filum Terminale: long filament of connective tissue, attaches to coccyx inferiorly • Cervical & Lumbar enlargements: where nerves for upper & lower limbs arise • Cauda Equina (horses tail): collection of spinal nerve roots ° SPINAL CORD ENDS AT L1, L2
where does the spinal cord exit above?
cervical region
white matter of spinal cord
~white matter: mylinated axons- makes tissue look white ° outer region of spinal cord = 3 faniculi ° composed of myelinated & unmylinated axons -allows communication between spinal cord & brain ~fibers classifed by type ° ascending fibers sensory = afferent tracts ° descending fibers motor = efferent tracts ° commisural fibers (communicating within CNS)
Gray matter of spinal cord & spinal roots
• dendrites, neurons, cell bodies •shaped like the letter \"H\" or a \"butterfly\" NO MYELIN • gray commissure: contains the central canal • dorsal horns: consists of interneurons • ventral & lateral horns: ONLY FOUND IN THORACIC & UPPER LUMBAR, contains cell bodies of motor neurons
Denticulate ligaments
•extension of spinal meninges, laterally anchor spinal cord • lateral extensions of pia mater
organization of gray matter of the spinal cord
•SS: somatic sensory = posterior horn •VS: visceral sensory = posterior horn •VM: visceral motor = anterior horn •SM: somatic motor = anterior horn •SENSORY ALWAYS IN DORSAL HORN •MOTOR ALWAYS IN VENTRAL HORN
meninges of the spinal cord
• pia mater: innermost layer of connective tissue, extends to coccyx, has denticulate ligaments: lateral extensions of pia mater • arachnoid mater: middle layer, looks like spiderweb •dura mater: tough mother, outer layer surrounding spinal cord
cerebrospinal fluid CSF
•constantly produced in brain •fills hillow cavities of brain & spinal cord •provides liquid cushion for spinal cord & brain •nourishes brain & spinal cord •removes wastes •carries chemical signals between parts of CNS
brains neural functions
•intelligence • consciousness •memory •sensory-motor integration •involved in innervation of the head
basic parts & organizatiin of brain
•divided into four regiona: ° cerebral hemispheres ° diencephalon ° brain stem: midbrain, pons, medulla oblungata ° cerebellum
organization of brain
• centrally located gray matter = nuclei • white matter = tracts of axons • cortex: means bark, additional outer layer of gray matter around white matter ° formed feon neuronal cell bodies, dendrites, unmylinated axons ° licated in cerebrum & cerebellum
ventricles of the brain
•4 expansions of the brains central activity • filled with CSF • lined with ependymal cells • continous with each other • continuous with the central canal of spinal cord ° although central canal of spinal cord is not always continuous
4 ventricles of the brain
•1. & 2. : lateral ventricles - locqyed in cerebral hemispheres, horseshoe shaped from bending of the cerebral hemispheres, connected with 3rd ventricle by interventricular foramen • 3rd ventricle: lies in diencephalon ° cerebral aqueduct: connects 3rd & 4th ventricles • 4th ventricle: lies in hindbrain ° connects to the central canal of spinal cord
the brian stem
• has 3 parts ° midbrain ° pons ° medulla oblongata
functions of brain stem
• producea automatic behaviors necessary for survival • passageway for all fiber tracts running between cerebrum & spinal cord • heavily involved with innervation of face & head
the medulla oblongata
• most caudal level of brain stem ° continuous with spinal cord ° choroid plexus lies in roof of fourth ventricle ° external landmarks of medulla • pyramids of the medulla= efferent motor tracts • lie on its ventral side • decussation of the pyramids • crossing over of motor tracts
External Landmarks of the Medulla Oblongata
  • Inferior cerebellar peduncles
  • Fiber tracts connecting medulla & cerebellum
  • Olive of the Medulla: contains inferior olivary nucleus- relays snsory info to cerebellum
Cranial Nerves attach/ arise from Medulla Oblongata # 8-12
VII. (8): Vestibulocochlear
IX. (9): Glossopharyngeal
X. (10): Vagus
XI. (11): Accessory
XII. (12): Hypoglossal
Core of the Medulla Oblongata Contains
  • Much of the reticular formation = gray matter, nuclei of ANS
  • Nuclei influence autonomic functions necessary for life
  • Visceral centers of reticular formation include:
  • Cardiac center
  • Vasomotor center
  • Medullary respiratory center
  • Centers for hiccupping, sneezing, swallowing, & coughing
The Pons
  • bridge between the midbrain, medulla oblongata, & cerebellum
  • Pons contains nuclei of cranial nerves:
  • V : Trigeminal
  • VI : Abducens
  • VII : Facial
  • Pons Contains: Motor tracts coming from cerebral cortex
  • Pontine nuclei
  • Connect portions of cerebral cortex & cerebellum
  • Sends zxons to cerebellum through middle cerebellar peduncles
The Midbrain
  • Lies between the diencephalon & the pons
  • Cerebral aqueduct (3rd ventircle --> 4th ventricle)
  • Central cavity of the midbrain
  • Cerebral peduncles: located on ventral surface of brain
  • Contains pyramidal (corticospinal) tracts
  • Superior cerebellar peducnles: connects midbrain to the cerebellum
  • Corpora Quadrigemina: largest nuclei, divided into superior & inferior colliculi
  • Superior colliculi: nuclei that act in visual reflexes
  • Inferior colliculi: nuclei that act in reflexive response to sound = auditory
The Cerebellum
  • located dorsal to the pons & medulla
  • smoothes an cordinates body movements
  • helps maintain equilibrium
  • Consists of two cerebellar hemispheres, each with 3 lobes
  • Surface folded into ridges: FOLIA (means leaf) separated by fissures
WHEN CEREBELLUM IS DAMAGED: RESULTS IN DIFFICULTY IN SPEECH, MEMORY, MOVEMENT, & EQUILIBRIUM
Hemispheres of the Cereblllum
  • Anterior Lobe & Posterior Lobe: coordinates trunk & appendage movements
  • Flocculonodular lobe (tiny): coordinates head & eye movements & posture/balance = equilibrium
Cerebellum composed of three regions
  • Cerebellar Cortex = gray matter
  • Arbor Vitae = "Tree of life": internal white matter ( looks like branching tree)
  • Deep Cerebellar nuclei: deeply situated gray matter
Functions of Cerebellum
  • Recieves information from the cerbral cortex: ( via pontine nuclei & middle cerebellar peduncles)
  • On equilibrium
  • On current movements of: limbs, neck, & trunk
The Cerebellar Peduncles (C.P.) of the Cerebellum
  • Fibers to & from cerebellum are ipsilateral: run to & from same side of body
  • Thick tracts connecting the cerebellum to Brain stem:
  • Superior C.P: info to cerebral cortex, via midbrain
  • Middle C.P: info from cerebral cortex, via pontine nuclei
  • Inferior C.P: info from vestibular nuclei (equilibrium) & spinal cord
The Diencephalon (think thalamus)
  • Forms center core of forebrain
  • Surrounded by cerebral hemispheres
  • Compsoed of 3 paired structures:
  • Thalamus
  • Hypothalamus
  • Epithalamus
  • Border the 3rd ventricle
  • primarily composed of gray matter
The Thalamus
  • makes up 80% of diencephalon
  • contain a dozen major nuclei: act as relay stations for incoming sensory message
  • Every part of brain communicating with cerebral cortex relays signals through thalamic nuclei!
  • Send axons to regions of the cerebral cortex
  • Afferent Impluses: synapse in at least one of its nuclei
  • The gateway to the cerebral cortex
  • Nuclei organize and amplify or tone down signals
The Hypothalamus
  • lies between optic chiasm & mammillary bodies
  • Pituitary gland projects inferiorly
  • Contains a dozen nuclei
  • Main visceral control center of the body: The Master Gland's Master!!!
Functions of the Hypothalamus
  • Control of the ANS: overlap with reticluar formation- so, these signals sens instructions to medulla oblongata & from there are carried out.
  • Control of emotional responses
  • regulates body temp
  • regulates hunger & thirst sensations
  • Control of behavior
  • regulation of sleep-wake cycles
  • control of endocrine system
  • formation of memory
The Epithalamus
  • Forms part of the "roof" top of 3rd ventricle
  • Consists of a tiny group of nuclei
  • includes pineal gland (pineal body):
  • Secretes hormone melatonin
  • Under influence of hypothalamus
  • Aids in control of circadian rhythm
The Cerebral Cortex
  • Home of our conscious mind
  • Enables us to:
  • Be aware of ourselves & our sensations
  • Initiate & control voluntary movements
  • Communicate, remember & understand
  • Composed of gray matter: neuronal cell bodies, dendrites, & short axons
  • Folds in cortex- triples its size
  • 40% of brain's mass
  • Brodmann areas : 52 structurally distinct areas
Functional Regions of Cerebral Cortex
  • Perform distinct motor & sensory functions
  • Memory & language spread over wide area
  • Has 3 general kinds of functional areas:
  • Sensory areas
  • Association areas
  • Motor areas
  • Primary sensory cortex: a specific brain region
Sensory Areas: Somatosensory Assocation Cortex
  • Integrates different sensory inputs: touch, pressure
  • Draws upon stored memories of past sensory experiences
  • You are able to recognize keys or coins in your pocket without looking at them
Motor Areas: Primary Motor Cortex
  • Controls motor functions
  • Primary motor cortex ( somatic motor area)
  • Located in precentral gyrus
  • Pyramidal cells: large neurons of primary motor cortex
  • Axons from these make up "pyramidal tracts"
  • Purkinse Cells: neurons in cerebellum
Cerebral Cortex White Matter
  • Communicates with the brainstem and spinal cord
  • Fiber communicating are: usually mylinated & bundled into tracts
Types of Cerebral Cortex White Matter Tracts
  • Commissures: composed of commissural fibers: allows communication between cerebral hemispheres
  • Corpus Callosum: largest commissure
  • Association Fibers: connect different parts of the same hemisphere
  • Projection fibers: run vertically, descend from cerebral cortex, ascends to the cortex from lower regions
  • Corticospinal tracts: begin with pyramidal cells
  • Internal Capsule: projection fibers from a compact bundle, passes between thalamus & Basal nuclei
  • Corona Radiata: superios to the internal capsule: fibers run to and from the cerebral cortex
Deep Gray Matter of Cerebrum
Consists of:
  • Basal ganglia: involved in motor control
  • Basal forebrain nuclei: associated with memory
  • Claustrum: nucleus of unknown function
  • Amygdala: located in cerebrum but is considered part of the limbic system
Basal Ganglia
  • group of nuclei deep within cerebral whtie matter
  • Receive input from many cortical areas
  • Start, stop, and regualte intensity of voluntary movements
  • estimate the passage of time
  • Basal Forebrain Nuclei: found in anterior & dorsal hypothalamus. Functions include: arousal, learning, memory, motor control
Brain Systems:
Networks of neurons functioning together
  • Limbic System: spread widely in the forebrain
  • The Reticular formation: spans the brain stem
The Limbic System
  • Located medial aspect of cerebral hemispheres, also within diencephalon
  • Compsoed of: septal nuclei,  cingulate gyrus, hippocampal formation, part of amygdala
  • The Fornix and other tracts link the limbic system together
Functions of Limbic System
  • The emotional brain
  • Cingulate gyrus: allows us to shift between thoughts, interperts pain as unpleasant
  • Hippocampal formation
The Reticular Formation
  • Runs through central core of Medulla, pons, and midbrain
  • Forms 3 columns:
  • Midline raphe nuclei
  • Medial nuclear group
  • Lateral nuclear group
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