Nolte – Chapter 3 (Gross Anatomy and General Organization of the Central Nervous System and Peripheral Nervous System) and all Class-Notes and Lab-Notes tagged with Chapter 3



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Nolte – Chapter 3 (Gross Anatomy and General Organization of the Central Nervous System and Peripheral Nervous System) and all Class-Notes and Lab-Notes tagged with Chapter 3.


  • Dorsal-Ventral all throughout CNS

    • The cephalic flexure would spate the axes, but we keep the terminology as if it was the same.

      • Cephalic flexure visible at the junction between the brainstem and the diencephalon.

  • Corpus collosum

    • Splenium at posterior

    • Body

    • Genu at anterior

      • Goes a bit ventral to the rostrum.

  • A particularly deep sulci is a fissure

  • Lobe and section markers

    • Frontal lobe

      • Anterior limit: None

      • Ventral Limit: Separated from the temporal lobe by the lateral sulcus (sylvian fissure)

        • Most ventral region is the orbital part.

      • Ventral Limit(Medial): On the medial surface extends to the cingulate sulcus (but doesn’t include)

      • Posterior Limit (Medial): imaginary continuation of the central sulcus to the cingulate.

    • Parietal Lobe

      • Anterior Limit: Central Sulcus

      • Posterior Limit: Imaginary line connecting the top of the parieto occipital sulcus and the preoccipital notch.

      • Ventral Limit: as if the calcarine and sylvian connected.

      • Vental Limit(Medial): subparietal and calcarine sulci

      • Posterior limit (medial) parietooccipital sulcus.

    • Temporal Lobe

      • Dorsal Limit: Sylvian Fissure extension to calcarine

      • Posterior Limit: line connecting top of the parietooccipital notch and the preoccipital notch.

      • Posterior Limit(Medial): imaginary line from preoccipital notch to the splenium.

      • Dorsal Limit (Medial): Collateral Sulcus.

    • Occipital Lobe

      • Anterior Limit: parietal and temporal lobes on both medial and lateral and surface.

    • Limbic Lobe

      • Encircles the telencephalon-diencephalon junction.

      • Interposed between corpus collosum and rest of cortical lobes.

  • The operculum covers the insula

    • Made up of frontal, parietal and temporal.

    • Circular sulcus outlines the insula and marks it borders with the opercula.

  • Gross Function/Anatomy

    • Precentral and forward is motor.

    • Post central and back is sensory.

    • IFG is split into 3

      • Oribital(anterior), triangular(middle), opercular(posterior up to the precentral gyrus).

        • Brocas is in Orbital and triangular.

    • Gyrus rectus

      • The medulla part of the frontal lob just medial to olfactory bulb

        • On the other side of the olfactory bulb(siting in its sulcus) st the orbital gyrus extension.

    • Parietal Lobe

      • Somatosensory

      • Postcerntral sulcus

      • Superior parietal Lobule

        • Intraparietal sulcus runs from the postcentral gyrus to the parietooccipital sulcus to separate it from the inferior parietal lobule.

      • Inferior parietal lobule

        • Made up of supramarginal gyrus(anterior up to the postcentral gyrus) and angular gyrus(rest)

        • Supramarginal caps the lateral fissure.

        • Angular caps the superior temporal gyrus.

      • Medial

        • Back to the parietoccipital sulcus is the precuneus and bounded ventrally by the calcarine.

        • All that is left after precuneus is the posterior paracentral lobule.

        • These two are separated by the cingulate sulcus.

    • Temporal Lobe

      • Superior Temporal gyrus

        • Primary auditory cortex

        • Wernicke’s area is the posterior most portion of this.

        • Wraps around in the anterior portion a bit to the medial

      • Medial side

        • Fusiform is most dorsal

          • Separated by the occipitotemporal sulcus from the inferior temporal sulcus

    • Occipital

      • ParietoOccippital and calcarine corner off the cuneus.

      • Just inferior to that calcarine sulcus is the lingual gyrus.

      • Most inferior is the fusiform gyrus

      • Lateral Side is all “lateral occipital gyri”

      • V1 is contained in the walls of the calcarine sulcus

        • Rest of the lobe is “visual association”

    • Limbic

      • Cingulate and parahippocampal

      • Cingulate is on top of diencephalon

        • After it hooks around the genu we see the subcollasal area cap off the cingulate gyrus.

      • Parahippocampal is below.

        • Anterior end that hooks back is the uncus.

          • Amygdala lies beneath the uncus and the hippocampus follows posteriorly.

        • Superior to it we see the hippocampal sulcus

  • Diencephalon

    • Thalamus has the third ventricle as a roof(their meeting point is the stria medullaris)

    • The medial surfaces are fused by the massa intermedia

    • Hypothalamic sulcus seperates the thalamus from the more inferior hypothalamus.

    • Hypothalamus connectes with the pituitary by the infundibular stalk.

    • More inferior are the mammillary bodies.

      • SCN takes 10% of retinal input

        • Right on top of optic chiasm

    • On the dorsal side, right above the superior colliculi, we find the pineal gland.

  • Midbrain

    • The tectum goes over the cerebral aqueduct and is made up of the collulculi and the brachium of the inferior.

    • The cerebral peduncles

    • Red nuclei

  • Pons

    • Pontine tegmentum forms floor of the fourth ventricle.

  • Medulla

    • Rostral open, caudal closed.

    • Medullary pyramids are just below the basal pons.

      • Decussate at region of medulla to the spinal cord.

  • Cerebellum

    • Vermis – midline

      • Lateral hemisphere encapsulating it

    • Anterior lobe

      • Separated by the primary fissure.

      • Afferent inputs from spinal cord

    • Flocculonodular lobe

      • Nodulus(vermal portion), flocculus(vestibulocochlear nerve)

      • Afferents from vestibular

    • Posterior love

      • Largest

      • Gets relay from pontine nuclei.

      • Coordination of voluntary movements.

  • Hippocampus

    • Efferent fiber bundle: fornix

    • Folded into the termporal lobe forming part of the wall of the alteral ventricle.

    • Becomes smaller as the temporal lobe curves into the parietal lobe.

      • Ends near the splenium of the CC

    • Fornix ends in the mammillary bodies.

  • Basal Ganglia

    • Lenticular nucleus

      • Putamen and globus pallidus

    • Caudate

      • Head in frontal lobe

      • Body and tail that follow the lateral ventricle around into the temporal lobe

      • Sepearted from the lenticular by the internal capsule which interconnects cerebrum with basal ganglia processes and thalamus

  • Relevant Cranial Nerves

    • II goes into the chiasm and becomes the tract

      • Only one that projects directly into the diencephalon(remember retina is actually part of diencephalon)

    • III emerges from the interpeduncular fossa between the cerebral peduncles.

      • This is just below the mammilarry bodies

        • The infundibulum is superior to mammillary bodies.

    • IV the only to emerge from the dorsal side

      • Just caudal to the inferior colliculi

    • V emerges from the lateral portion of the basal pons.

  • Miscellaneous

    • Thalamocortical fibers are uncrossed

    • Cerebellum is ipsilateral

    • Spinothalamic is pain-temperature

    • Cerebellar outputs return to the motor cortex and affect corticospinal activite (but go through thalamus)

      • Must cross midline before thalamus.

      • Basal ganglia also affect motor output this way.

        • They don’t receive sensory input as directly, though.

    • Layer IV receives sensory input

    • Layer V is output (pyramidals)

      • Go down through the peduncles and medulla(decussate) and go down the spinal cord to contact primary motor neurons

        • This is the coricospinal tracts

    • Layer VI receives input from thalamus


Peripheral Nervous System


  • Peripheral nerves do not cross the midline

  • Afferent

    • Go towards the CNS

    • Primary afferents in the dorsal root ganglia hug the spinal cord

      • These are psudounipolar

  • Efferent

  • Dorsal-Ventral

    • Bell-Magendie Law

      • Sensory axons enter the dorsal root

        • But not limbo-sacral pain fibers

      • Motor axons exit via the ventral root

  • Plexi

    • Organized web of fibers like a tree branch that get more and more focal as you get closer to innervations.

      • E.g: brachial plexus will cover everything in the arms.

  • Peripheral Nerves and Conduction

    • Ia are primary muscle spindle afferents

    • Ib are golgi tendon organ afferents

    • II are spindle secondaries

      • Meissner, merkel, etc.

    • III are free nerve endings for temperature and sharp pain

    • IV(c) are free nerve endings as well

      • Unmyelinated

      • Slow pain

    • Reception depends on intensity and duration

    • Receptor type depends on location and quality

      • homonculus

    • Extrinsic mechanism can affect reception as well

      • bright light can be received but can also trigger a contraction of the pupil.

      • intrafusal and extrafusal efferents can made more and less sensitive.

  • Glia

    • Schwann

      • Wrap around the axon in an engulfing fashion

      • also provide metabolic support

        • especially in dorsal root ganglia

      • they can make a type of matrix and rovide scaffolding for axonal growth after injury.

  • Muscle Spindles

    • receptor organs that lie in parallel to our muscle fibers

    • tell us about the length of our muscle and the rate of change of this muscle

    • nuclear chain fibers and their flower outbranches respond primarily to length and will fire when the muscle is lengthened.

    • nuclear bag fibers with their annulospiral endings will to the rate of change

    • Gamma motor neurons will regulate the sensitivity to stretch when muscle is relaxed.

      • allows the nucleur bag to stay tense

  • Golgi tendon organs are between the muscle and tendon and will be activated by isometric contractions.

    • respond to tension

    • slow adapting, so they can keep up the maintenance.

  • Autonomic Nervous System

    • nerves that go to our viscera

    • all the efferents go through a ganglia

    • Sympathetic

      • flight or fight

      • efferents comes out of ventral horn

        • B type fibers will synapse near the sympathetic ganglion with acetylcholine and then innervate with norepinephrine.

          • except for sweat glands which are cholinergic.

          • preganglionic can also innervate the adrenal medulla that then secretes norep.

      • the sympathetic ganglion are near the spinal cord

        • and primarily in thoracic and upper lumbar

          • thoracolumbar outflow.

        • can be interconnected to form a sympathetic chain.

      • travel from spinal cord to the sympathetic chain ganglion via the white communicating rami

    • Parasympathetic

      • more normal

      • Ganglion are closer to the vicera of interest

      • use acetylcholine on parasympathetic ganglia and the actual viscera.

      • mainly in sacral spinal nerves and cranial nerves

        • none in the limbs

      • more focal in its control than the sympathetic.

    • There is always a stop at autonomic ganglia(post ganglionic)

      • the preganglionic has its cell body in the CNS and are thinly myelinated in route to the ganglia.

        • the actual postgalionic innervations are unmyelinated.

      • this is different from the somatic motor system where we just have the cell body in CNS whose axons go directly to skeletal muscle.

  • Injuries

    • damage to a nerve causes willerian degeneration, where neurons distal to the cut will start to die and the axon will regress to the closest node of ranvier.

      • the schwann cells will remain, though, as scaffolding.

    • Collateral sprouting can occur from preserved tips f axons

      • they can follow the NGF given off by schwann cells and simultaneously grow through the schwann scaffolding.

  • Pain

    • Nociceptive.

      • hurt ow.

    • Neuropathic

      • dull aching (due to damage of neural tissue)

    • Free nerve endings release potassium and other chemical mediators

    • C fibers

      • slow conduction(no myelinated)

      • 2nd pain

    • A-delta Fibers III

      • fast conducting

      • 1st pain

    • Gate-Theory

      • incoming pain stimuli can be regulated because the incoming stimuli compete with sensory inputs and cortical modulations.

        • we rub periphery so that the signal can compete

        • touch will be faster than the slow transmitting c fibers, so we keep touching and rubbing to overpower the slow pain.

    • Referred pain

      • the area to which pain is referred correspond to the dermatome innervated by the spinal segment to which the visceral afferent project.

        • visceral afferent fibers accompany sympathetic efferents

          • subserve visceral reflexes and don’t really reach consciousness but can if it is enough or if the organ is inflamed.



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