Ch 15: Brain and Cranial Nerves Ch 15: Brain and Cranial Nerves ■ Discuss the organization of the brain, Discuss the organization of the brain, including the major structures and their including the major structures and their functions functions ■ Describe the meninges of the spinal cord Describe the meninges of the spinal cord and brain, and integrate the formation and brain, and integrate the formation and flow of CSF with this information. and flow of CSF with this information. ■ Describe the structures that constitute Describe the structures that constitute the BBB and their functions the BBB and their functions ■ Review the cranial nerves, again giving a Review the cranial nerves, again giving a brief function of each. brief function of each.
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Ch 15: Brain and Cranial NervesCh 15: Brain and Cranial Nerves■ Discuss the organization of the brain, Discuss the organization of the brain,
including the major structures and their including the major structures and their functionsfunctions
■ Describe the meninges of the spinal cord Describe the meninges of the spinal cord and brain, and integrate the formation and brain, and integrate the formation and flow of CSF with this information.and flow of CSF with this information.
■ Describe the structures that constitute Describe the structures that constitute the BBB and their functionsthe BBB and their functions
■ Review the cranial nerves, again giving a Review the cranial nerves, again giving a brief function of each.brief function of each.
Gray & White Matter OrganizationGray & White Matter Organization
In In brain stem brain stem similar to spinal similar to spinal cord (cord (nuclei around nuclei around ventricles, tracts on ventricles, tracts on outside)outside)
In In cerebrumcerebrum and and cerebellumcerebellum: white : white matter covered matter covered with layer of with layer of neural cortex neural cortex (grey)(grey)
3. 3. Pia materPia mater - "delicate - "delicate mother"mother"
Arachnoid granulations: This is where the CSF produced in the choroid plexuses of the ventricles and which has circulated into the subarachnoid space is reabsorbed.
Longitudinal fissure
Four VentriclesFour VentriclesCSF filled chambersCSF filled chambersCommunicating with central canal of spinal cordCommunicating with central canal of spinal cord
Lined by ependymal cells
CSF: Cerebro-Spinal Fluid■ Formation in ventricles by specialized Formation in ventricles by specialized
ependymal cells of ependymal cells of choroid plexuseschoroid plexuses (~500 (~500 mL/day; total volume ~ 150 mL)mL/day; total volume ~ 150 mL)
■ FunctionsFunctions– transport medium, in transport medium, in – shock absorption shock absorption – buoyancybuoyancy (floats the brain)(floats the brain)
■ CSF circulation: Ventricles central canal →CSF circulation: Ventricles central canal → subarachnoid space→ subarachnoid space→
■ Reabsorption into circulation via Reabsorption into circulation via arachnoid arachnoid granulationsgranulations into superior sagittal sinus. into superior sagittal sinus.
3 areas in brain don’ t have BBB3 areas in brain don’ t have BBB3.3. portion of hypothalamus portion of hypothalamus 4.4. pineal gland (in diencephalon) pineal gland (in diencephalon) 5.5. choroid plexuschoroid plexus
■ Two hemispheres Two hemispheres separated by separated by longitudinal fissurelongitudinal fissure
■ Gyrus (gyri) separated by sulcus (sulci)Gyrus (gyri) separated by sulcus (sulci)
■ Major lobes named Major lobes named after overlaying bones after overlaying bones
■ . . have functional regions (motor, sensory and association areas)
■ . . . have some functional differences (in spite of anatomical resemblance) Lateralization of cortical →functioning
■ . . . receive information and generate commands for opposite side of body
Cerebral Cortex and Central White MatterCerebral Cortex and Central White Matter
Gray surface (cortex) with white tracts internallyGray surface (cortex) with white tracts internally
CommissuresCommissures – connect corresponding gyri of the – connect corresponding gyri of the two hemispheres two hemispheres 1) corpus callosum1) corpus callosum2) anterior commissure2) anterior commissure
Projection tracts (fibers)Projection tracts (fibers) – connect more or less – connect more or less verticallyvertically
Association tracts (fibers)Association tracts (fibers) – connect one gyrus – connect one gyrus to another in the same hemisphereto another in the same hemisphere
Hypothalamus Just superior to optic chiasma Infundibulum - connects to pituitary gland Some functions:
Control of autonomic nervous system Coordination of nervous and endocrine systems Secretion of hormones - ADH and oxytocin
Mesencephalon)Mesencephalon)= Midbrain = Midbrain
Corpora quadrigemina Corpora quadrigemina = 2 pairs of sensory nuclei= 2 pairs of sensory nuclei– Superior colliculi Superior colliculi (relay station for visual information)– Inferior colliculi Inferior colliculi (relay station for auditory informationinformation
Substantia nigra - regulates motor outputSubstantia nigra - regulates motor output
Cerebral peduncles - ascending and descending Cerebral peduncles - ascending and descending tracts to thalamustracts to thalamus
Nuclei of ori for CN III and IVNuclei of ori for CN III and IV
– 2 attach to forebrain 2 attach to forebrain (Telen- & (Telen- & Diencephalon)Diencephalon)
– 10 attach to 10 attach to brainstembrainstem(Mes-, Met- and Myelencephalon)(Mes-, Met- and Myelencephalon)
■ Names relate toNames relate to appearance or appearance or
functionfunction
■ Classification ?Classification ?
Olfactory Nerve (= CN or N I)Olfactory Nerve (= CN or N I)
1º function?1º function?
Origin?Origin?
Destination? _____________(By way Destination? _____________(By way of cribiform plate of ethmoidof cribiform plate of ethmoid))
Only CN directly attached to CerebrumOnly CN directly attached to Cerebrum
Optic Nerve (N II)Optic Nerve (N II)
1º fu?1º fu?
ori?ori?
dest? - dest? - by way by way of optic of optic foramen of foramen of sphenoid to sphenoid to Diencephalon Diencephalon (optic chiasma) (optic chiasma) and to and to occipital lobeoccipital lobe
Oculomotor (N III)Oculomotor (N III)
C: Motor C: Motor
O: MesencephalonO: Mesencephalon
D: Somatic motor to superior, inferior, medial D: Somatic motor to superior, inferior, medial recti and inferior oblique; visceral motor to recti and inferior oblique; visceral motor to intrinsic eye musclesintrinsic eye muscles
by way of superior orbital fissure by way of superior orbital fissure
Trochlear (N IV)Trochlear (N IV)
C: Motor C: Motor
O: MesencephalonO: Mesencephalon
D: superior obliqueD: superior oblique
by way of superior orbital fissureby way of superior orbital fissure
Trigeminal (N V)Trigeminal (N V)
C: Mixed C: Mixed three major branchesthree major branches
D: sensory nuclei in pons / muscles of masticationD: sensory nuclei in pons / muscles of mastication
AbducensAbducens(CN VI)(CN VI)
C: Motor O: PonsD: Runs lateral rectus eye muscle
Facial (N VII)Facial (N VII)
C: Mixed C: Mixed
O: sensory from taste receptors of O: sensory from taste receptors of anterior 2/3 of tongue / motor from pons anterior 2/3 of tongue / motor from pons
D: Sensory to sensory nuclei of pons / D: Sensory to sensory nuclei of pons / motor muscles of facial expression, motor muscles of facial expression, visceral motor to tear gland.visceral motor to tear gland.
O: sensory from posterior 1/3 of tongue / motor from medulla oblongata
D: medulla / muscles for swallowing, parotid gland
Vagus (N X)Vagus (N X)
C: Mixed C: Mixed
O: O: Sensation from pharyngeal area and Sensation from pharyngeal area and outer earouter ear / motor from medulla / motor from medulla
D: D: Sensory to medullaSensory to medulla / / visceral visceral motor to thoracic and motor to thoracic and abdominal cavities and their abdominal cavities and their organs. organs. Major motor pathway Major motor pathway for ANSfor ANS
Accessory (N XI)Accessory (N XI) and and C: Motor C: Motor O: Motor nuclei of medulla O: Motor nuclei of medulla and spinal cordand spinal cordD: Swallowing, trapezius & scm musclesD: Swallowing, trapezius & scm muscles
Hypoglossal (N XII)Hypoglossal (N XII)C: Motor C: Motor O: Motor nuclei of medulla O: Motor nuclei of medulla D: Tongue musculatureD: Tongue musculature
Mnemonic
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