UNIVERSITY OF NEW ENGLANDCollege of Health Professions

NEUROSCIENCE LAB MANUAL(BIO 504)

2010

This material is for the sole use of the College of Health Professions neuroscience course at the University of New England

This manual is copy written

9th Edition

GROSS ANATOMY LABORATORY PROCEDURES

1. Appropriate laboratory attire is required: Long pants, close-toed shoes (no Crocs), safety glasses and Nitrile gloves (for human tissue)

NO shorts or skirts permitted, even if made from scrub materialSafety glasses for splash protection are available in the labGloves will be provided; please try to limit use to ~1 pair / sessionLong hair must be tied back, away from the face. Long necklaces should be removedContact Lenses are NOT advised,

as they are permeable to volatile compounds and may result in injuryStudents should bring their lab manual to lab sessions

2. No food or beverages are allowed in the laboratory - EVER.

Smoking and / or chewing gum is prohibited in the laboratory

3. No cadaveric material (or models) are EVER to be removed from the Neuroscience lab

This is a State of Maine and a Federal law. You WILL be prosecuted to the fullest extent of the law

Models, prepared specimens, etc. are available during scheduled class and open lab timesAny student who damages a model will be held financially responsibleModel keys can be found at http://faculty.une.edu/cas/fdaly or in the 3-ring notebooks in lab

4. No gloves should be worn outside of the lab or while a student is handling models

This also pertains to x-ray lightboxes, LCD screens and blackboardsThe reason that you wear gloves is to protect yourselfHandling “clean” material with dirty gloves negates the safety of using gloves

5. Keep the floor free from material that might fall from the laboratory tables

The embalming fluid and glycol is VERY slipperyTo avoid falling hazards, please clean slippery spots immediately (Don’t wait to be asked!)Spray Simple Green on the greasy spot AND wipe until dry – just spraying is NOT enough.

6. Please keep all material (skin , organs, limbs, brains) at the table with the rightful “owner”

This is to ensure that when the cadavers have finished their role at the University, they will be returned in full to the surviving family members

7. Keep the cadaveric tissue moistened with the wetting solution provided (Infutrace)

Infutrace minimizes the vaporization of the phenolic compounds in the embalming solutionHelp maintain the dissections by making sure that the body bags are closed

8. There are no “clean sinks” in the lab

The sinks in the lab are used to wash tools and trays, as well as handsWash your hands prior to leaving the lab AND again after changing in the locker room

9. Pregnant or nursing women are STRONGLY discouraged from participating in the laboratory

There is evidence that indicates women exposed to phenolic solvents during pregnancyhave increased incidence of children born with congenital birth defects

Those interested in laboratory alternatives will be accommodated

10. Report all injuries sustained in laboratory to the instructor

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You will be required to fill out an injury report form. Forms are located in wall hangers near sinks in lab

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REFERENCES:

Gilroy AM, MacPherson BR, Ross LM (2008) Atlas of Anatomy, Thieme

Kandell ER, Schwartz JH, Jessel TM (2000) Principles of Neural Science (4th Ed.) McGraw Hill

Moore KL, Dalley AF (1999) Clinically Oriented Anatomy (4th Ed.) Lippincott Williams & Wilkins

Nolte J (1999) The Human Brain: An Introduction to Its Functional Anatomy (4th Ed.) Mosby

Netter FH (2003) Atlas of Human Anatomy (3rd Ed.) Icon Learning Systems

Stedman’s Medical Dictionary 27th Ed. (2000) MB Pugh (editor) Lippincott, Williams & Wilkins

Sandmire D (1999) Neuroscience Lab Handouts, unpublished

Snell RS (2001) Clinical Neuroanatomy for Medical Students (5th Ed.) Lippincott Williams & Wilkins

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LAB 1: Gross Anatomy, Meninges and Blood Supply

Nervous System

Identify the organs/structures associated with the central nervous system and the peripheral nervous system

Identify the location of gray matter and white matter in the brain and the spinal cord and relate significance of terms

Define the following terms:

nerve / tract ganglion / nucleus afferent / efferent plexus sulcus / gyrus

Differentiate between cranial and spinal nerves, by knowing the correct number and location of each (spinal nerves)

Describe / define the following terms associated with the autonomic nervous system

parasympathetic division sympathetic division

craniosacral thoracolumbar

cranial nerves (CN X) splanchnic nerves

prevertebral ganglia (mixed) paravertebral ganglia

Locate nerves / plexuses on a model

brachial plexus lumbrosacral plexus cervical plexus (ansa cervicalis) sympathetic chain

(C5-T1) (T12-S3) (C1-C4)

CEREBRAL CORTEX Longitudinal Fissure separates RIGHT and LEFT hemispheres(Telencephalon)

FRONAL LOBE: Identify the following structures

lateral sulcus central sulcus pre-central gyrus (primary motor cortex)

frontal gyri (pre-motor cortex) (pre-frontal cortex)

central sulcus – separates motor (anterior) from sensory (posterior) cortexAlso used to distinguish frontal cortex from parietal cortex

lateral sulcus – separates frontal and parietal lobes from temporal lobe (fissure) on superior surface is auditory cortex

Primary Motor Cortex (M1, Area 4) – Cortex fold immediately anterior to central sulcusDisproportionate body map (homunculus) superimposed on gyrusOriented with feet in longitudinal fissure, hips around apex of cortex, trunk superior,

hand superolateral, head / face lateral, and oral cavity inferolateral (L. sulcus)

pre-motor cortex – anterior to primary motor cortex

pre-frontal cortex – anterior to pre-motor cortex

Broca’s Area – inferior frontal gyrus (opercular and triangular parts) of left hemisphereAssociated with written/spoken language – aphasia

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PARIETAL LOBE: Identify the following structures

post-central gyrus parietooccipital sulcus (primary somatosensory cortex)

Primary Sensory Cortex (S1, Areas 3,1,2) – cortex fold immediately posterior to central sulcusSensory homunculus superimposed on gyrusOriented with feet in longitudinal fissure, hips around apex of cortex, trunk superior,

hand superolateral, head and face lateral, and oral cavity inferolateral (L. sulcus)

parietooccipital sulcus – separates parietal from occipital lobeEasily seen on medial surface running from superior cortex toward corpus callosum

TEMPORAL LOBE: Identify the following structures

temporal gyri (primary auditory cortex) uncus hippocampus amygdala

temporal gyri – superior, middle and inferior

Primary Auditory Cortex (A1, Area 41) – posterior superior temporal gyrusTonotopic map of auditory space – low tones different region from high tones

Wernicke’s Area – superior temporal gyrus (posterior part) of left hemisphereAssociated with language comprehension

uncus – inferior medial temporal lobe – contains amygdala and hippocampus

hippocampus – medial temporal lobeAssociated with memory formation

amygdala – anterior medial temporal lobe, anterior to hippocampus

Associated with emotion

INSULA: Identify the insula deep to frontal and temporal lobes

Union of diencephalon with telencephalon

Cortex covering basal ganglia

OCCIPITAL LOBE: Identify the following structures

Calcarine sulcus (primary visual cortex)

Primary Visual Cortex (V1, Area 17) – occipital pole and medial surface of occipital lobe (sup/inf to calcarine sulcus)

visual association cortex – cortex outside of primary visual cortex, spreading from occipital cortex to parietal and temporal cortex

Calcarine sulcus – fissure running through center of medial occipital lobe

Identify the locations of the lateral ventricles

Identify the cranial nerve associated with the cerebral cortex - olfactory nerve (CN I)

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Diencephalon

Identify the structures of the diencephalon:

pineal gland pituitary gland infundibulum interthalamic adhesion

epithalamus hypothalamus mammillary bodies thalamus geniculate bodies

epithalamus – posterior part of diencephalonIncludes pineal gland and habenular nuclei (eating behavior)

hypothalamus – inferior part of diencephalon Infundibulum connects to pituitary glandIncludes nuclei to help regulate body temperature, fluid osmolarity

thalamus – egg-shaped mass of nuclei in lateral walls of diencephalonSensory switchboard / relay for information going to cortexposterior to basal ganglia, superior to internal capsuleVarious nuclei make up thalamus, each sending information to specific regions

Medial Geniculate Nuclei – auditory information to auditory cortexLateral Geniculate Nuclei – visual information to V1

Identify the structures of the hemi-sected brain:

corpus callosum septum pellucidum optic nerve/chiasm

cingulate gyrus parahippocampal gyrus uncus

corpus callosum – C-shaped structure connecting frontal, parietal, temporal and occipital lobes of cortex mylenated commissure between left and right hemisphereLargest of commissures

cingulate gyrus – cortex fold superior to corpus callosum associated with perception of pain

internal capsule – mylenated motor fibers from motor cortex to pontine nuclei or spinal cord

basal ganglia – extrapyramidal motor area

Caudate / Putamen – nuclear masses on either side of internal capsule (Striatum) caudate (L. nucleus w/tail) – lateral ventricle

putamen (L. husk) – inferior to internal capsule, medial to insula

Globus Pallidus – medial to putamen

Substantial Nigra – inferior to globus pallidusMajor site of dopamine production

Identify the location of the 3rd ventricle

Identify the cranial nerves associated with direct access to the thalamus - optic nerve (CN II)

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Brainstem

Identify the structures of the brainstem:

cerebral peduncle optic tract pons superior / inferior colliculi

pons sup/inf/mid cerebellar peduncles cerebral aqueduct

medulla oblongata pyramids olive cuneate/gracile tubercle

cranial nerves (III-XII)

midbrain – connection to diencephalon(Mesencephalon) Contains cranial nerve nuclei and evolutionarily older structures (colliculi)

pons – walnut shaped structure on ventral surface of brainstem(Metencephalon) For passing and synapsing tracts involved with muscle movement

From cortex to spinal cord and cerebellum

Also region where cerebellum connects to brainstem via cerebellar peduncles

medulla oblongata – connection to spinal cord(Mylencephalon) Contains motor tracts, some cranial nerve nuclei and proprioceptive nuclei

Pyramidal tracts produce medial swellings (pyramidal motor system)Inferior Olivary Nuclei produce lateral swellings (vestibular extrapyramidal system)

Cerebellum Gyri called folia because of leaf-like appearance (Metencephalon) (extrapyramidal motor area)

Identify the structures of the cerebellum

vermis anterior lobe posterior lobe flocculonodular lobe

sup/inf/mid cerebellar peduncles primary fissure arbor vitae

vermis – dorsal central cerebellum – adjacent to occipital cortexReceives afferent sensory information from spinal cord (spinocerebellar tract)

anterior lobe – superior cerebellum, separated from posterior lobe by primary fissureReceives proprioceptive information from afferent fibers in spinal cord

posterior lobe – makes the bulk of the cerebellum – inferior to primary fissureReceives efferent motor information from the cerebral cortex / pons

flocculonodular lobe - lateral to cerebellar attachment (cerebellar peduncle) to brainstemReceives afferent vestibular information from CN VIII nuclei and effects eye movements

Identify the location of the 4th ventricle

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Identify structures in plastic coronal / horizontal / mid-sagittal sections

internal capsule caudate putamen globus pallidus

basal nuclei (ganglia) striatum central sulcus lateral sulcus

pre-central gyrus post-central gyrus cerebral arteries carotid artery

lateral ventricles 3rd ventricle pineal gland pituitary gland

interthalamic adhesion infundibulum corpus callosum cingulate gyrus

septum pellucidum posterior commissure anterior commissure cerebral aqueduct

insula geniculate nuclei superior / inferior colliculi cerebral peduncle

hippocampus pons medulla oblongata pyramids

olive cerebellar peduncles 4th ventricle vermis

cranial nerves (any) flocculonodular lobe

CEREBRAL BLOOD SUPPLY

Trace the arterial blood flow to the brain: Skull Entry and major blood supply

Heart >> aortic arch >> common carotid arteries >> internal carotid artery >> Cerebral Arterial Circle (of Willis)

Heart >> aortic arch >> subclavian artery >> vertebral artery >> basilar artery >> Cerebral Arterial Circle (of Willis)

Internal Carotid ArteriesEnter skull via carotid canal of temporal bone (right and left)Each branches into…

ophthalmic artery – orbital muscles, glands and retinaanterior cerebral artery – medial cerebral hemispheres except occipital lobe

frontal and parietal lobes, corpus callosum- small branch connects right and left sides called anterior communicating artery

middle cerebral artery – lateral cerebral hemispheres and choroid plexusfrontal, parietal, temporal and insular lobes and internal capsule

posterior communicating artery – connect ICA to posterior cerebral artery

Discuss the Cerebral Arterial Circle (of Willis), including general flow of blood, arterial branches and region supplied

carotid arteries cerebral arteries ophthalmic arteries communicating arteries

choroidal arteries perforating arteries (lenticulostriate & thalamotuberal arteries)

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basilar artery cerebellar arteries labyrinthine arteries vertebral arteriesCerebral Arterial Circle (of Willis)

Anastomosis of cerebral arteries anterior cerebral arteries joined by anterior communicating arteryposterior cerebral arteries joined to internal carotid by posterior communicating arteries

Vertebral ArteriesPass through foramen magnum and join together to form basilar arterySingle branch …

posterior inferior cerebellar artery (PICA) – blood to inferior cerebellum (flocculonodular lobe)

Basilar ArteryVentral to pons within the posterior cranial fossa (anterior to foramen magnum)Branches include…anterior inferior cerebellar arteries (AICA) – blood to middle cerebellumlabyrinthine arteries – blood to inner earpontine arteries – blood to ponssuperior cerebellar arteries – blood to superior cerebellumposterior cerebral arteries – blood to medial temporal and occipital lobes

- small (communincating) branch connects to internal carotid artery

Identify the major arterial branches of the basilar / vertebral arteries:

superior cerebellar artery anterior inferior cerebellar arteries labyrinthine artery pontine arteries

Discuss the blood supply to the spinal cord and their origins

One anterior spinal artery Two posterior spinal arteries

anterior spinal artery - in anterior median fissure from vertebral, posterior intercostal and lumbar arteries

posterior spinal arteries - close to dorsal (sensory) rootlets of spinal cord

from vertebral, posterior intercostal and lumbar arteries

Cerebrospinal Fluid

Discuss the flow of cerebrospinal fluid and locate the specific structures:

lateral ventricles 3rd ventricle 4th ventricle subarachnoid space/ cisterns

CSF is created by the choroid plexus located in each of the ventricles of the brainIt protects the brain by providing cushionIt flows from…

1 - lateral ventricles in cerebral hemispheres2 – to 3rd ventricle located in the diencephalon (between right and left thalami)3 – through cerebral aqueduct deep to superior and inferior colliculi4 – into 4th ventricle located between pons/medulla oblongata and cerebellum5 – enters central canal of spinal cord or sub-arachnoid space around brain

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interventricular foramen (of Monro) cerebral aqueduct median (Magendie) aperture &lateral (Luschka) apertures

Sub-Arachnoid Cisterns - for cerebrospinal fluid pooling

Describe the anatomical significance of the subarachnoid space, arachnoid trabeculae, and arachnoid villi

Interpeduncular Cistern - between cerebral peduncles (CNIII)

Pontine Cistern – ventral / caudal to ponsAt the junction between the pons and medulla oblongata (CN VI)

Cerebellomedullary Cistern (Cisterna Magna) - posteroinferior (caudal) to cerebellum (CN X)At the junction between cerebellum and medulla oblongataLargest CSF pool in head

Superior (Quadreminal) cistern – between corpus callosum and cerebellumPosterior to colliculi

Lumbar Cistern - inferior to spinal cord (L3-L5) At level of sacral rami Easy access CSF

MENINGES

Protect brain, framework for blood supply and enclose the cerebrospinal fluid.

Discuss the primary innervation for the meninges - trigeminal nerve (CNV)

Identify the meningeal membranes and describe the differences of each

Dura Arachoid Pia

Dura Mater - external thick outer dense fibrous membrane with two layers, periosteal and meningealDural sinuses which drain blood from the brain reside between these two layers

Arachnoid Mater - intermediate membrane / mesh of fibers (trebeculae)Location of large blood vesselsSub-Arachnoid space filled with cerebrospinal fluid

Pia Mater - internal, vascular memebrane adjacent to brainFollows sulci and gyri intimatelyDoes NOT penetrate cortex to follow blood vessels

Describe the anatomical significance of the subarachnoid space, arachnoid trabeculae and arachnoid villi/granulations

Locate the following folds of the dura mater:

cerebral falx cerebellar falx cerebellar tentorium sellar diaphragm

Dural folds divide the cranium into parts and support brain –

Cerebral falx – largest fold – midsagittal between right and left hemispheres

Cerebellar falx – midsagittal fold between right and left sides of cerebellum

Cerebellar tentorium – horizontal fold between cerebellum and cerebral hemispheres

Sellar diaphram – suspended between clinoid processes to cover pituitary gland

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Discuss the dural sinuses and their function within the skull

superior sagittal sinus inferior sagittal sinus great cerebral vein straight sinus

confluence of sinuses transverse sinus sigmoid sinus occipital sinus

petrosal sinuses cavernous sinus sphenoparietal sinus

Superior sagittal sinus – within longitudinal fissure – attached to skull (cerebral falx)

Inferior sagittal sinus – between cerebral hemispheres superior to corpus callosum (cerebral falx)

Great cerebral vein – between thalami and inferior to splenium of corpus callosum

Straight sinus – between cerebral hemispheres and cerebellum (tentorium cerebelli and cerebral falx)

Confluence of sinuses – joining of superior sagittal, straight, occipital and transverse sinuses

Transverse sinus – lateral toward temporal bone (tentorium cerebelli)

Sigmoid sinus – in S-shaped groove of temporal bone leading to jugular foramen

Occipital sinus – inferior to internal occipital protuberance withing cerebellar falx

Petrosal sinuses - connect transverse/sigmoid sinus to cavernous sinus

Cavernous sinus – lateral to pituitary gland and surrounds internal carotid artery and cranial nerves III, IV, V1, V2, & VI

Sphenoparietal sinus – run along lesser wing of sphenoid bone to lateral cranial vault

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LAB 2: Spinal Cord, Brainstem and Cranial Nerves

SPINAL CORD

Locate the following structures of the spinal cord

dorsal / ventral horn intermediate / lateral horn central canal commissure

funiculus / fasciculus anterior median fissure posterolateral sulci dorsal / ventral root

dorsal root ganglia dorsal / ventral rami cauda equina terminal filament

cervical / lumbar enlargement medullary cone lumbar cistern denticulate ligaments

Spinal cord, meninges and related structures (blood vessels / epidural fat) are located within the vertebral canal

Cord is cylindrical with slightly flattened anterior and posterior surfacesExtends from foramen magnum (occipital bone) to L2 (45cm long) - upper 2/3 of the vertebral columnCord tapers inferiorly to end as the medullary cone (conus medularis)

Cervical enlargement (C4 - T1) – ventral rami make brachial plexus (upper extremity innervation)

Lumbosacral enlargement (T11 – L1) – ventral rami make up lumbrosacral plexus (lower extremity innervation)

Cauda Equina – bundle of spinal nerve roots running inferiorly through the lower 1/3 of vertebral column

Terminal Filament (filium terminale) – extension of pia (from medullary cone) that attaches to the coccyxholds spinal cord in place at inferior end of vertebral columndural sac (dura inferior to medullary cone) anchors to filium terminale

Anterior Longitudinal (Median) Fissure - ventral fissure between RIGHT and LEFT sides of the spinal cordProvides space for anterior spinal artery

Posterolateral Sulci - depressions in dorsal surface for entrance of dorsal rootlets (sensory)Provides space for posterior spinal arteries

Dorsal Horn – Associated with sensation / afferent informationContains cell bodies of interneurons – sending info up to brain, to ventral horn and commissuralConnected to dorsal root via Lissauer’s Tract

Ventral Horn – Associated with motor function / efferent informationContains cell bodies of lower motor neurons – sending info to muscles

Intermediate Horn – located laterally between dorsal and ventral horns in thoracolumbar regions Associated with autonomic nervous systemMotor neuron cell bodies for sympathetic (fight or flight) response

Posterior Funiculi – between the right and left dorsal hornsAssociated with proprioception and touch sensory information travelling to post-central gyrus

In bundles called posterior columns or fasciulus gracilis / cuneatusFasiculus Gracilis – T6 inferior sensory information - medialFasiculus Cuneatus – T6 superior sensory information – lateral Both terminate in the medial leminiscus of brainstem via arcuate fibers in medulla oblongata

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Anterior Funiculi – between right and left ventral hornsAssociated with vestibulospinal tract, pontoreticulospinal tract, anterior cortical spinal tract and

medial longitudinal fasiculus (vision, vestibular and cervical motor)Coordinating head, neck and eye movements

Lateral Funiculi – between left / right dorsal and ventral horns Associate with cortical motor information travelling to different spinal levels (corticospinal tract) Pain / temperature information travelling to post-central gyrus (spinothalamic tract)

Agonist / Antagonist muscle sensory info to cerebellum (spinocerebellar tract)

Compare the spinal cord meninges with the cerebral meninges

Dura Mater – outer tough connective tissue membrane of the spinal cord.connects to the interior margins of foramen magnum and inferiorly anchored to coccyx by filium terminalesuperficial to dura is the epidural fat to help hold the spinal cord in place.

Arachnoid Mater– avascular membrane that lines the dura (not attached)creates subarachnoid space that is filled with Cerebrospinal Fluid (CSF)

lumbar cistern – L2-S2- CSF pool

Pia Mater – innermost covering of spinal cordcreates the filium terminale within the lumbar cisternmakes up the denticulate ligaments - saw-tooth-like connections between pia and arachnoid

Discuss the blood supply to the spinal cord - 1 anterior and 2 posterior arteries

All receive their blood from vertebral, intercostal arteries as well as some other arteries.Radicular arteries run along nerve roots

There is a longitudinal venous plexus which drains the spinal cord (internal vertebral venous plexus)Free communication of venous blood within epidural spaceSuperiorly communicates with venous sinuses of head Inferiorly communicates with external vertebral venous plexus around the vertebral bodies

Spinal Nerves

Discuss the spinal nerves, including numbers and dermatomes

31 pairs of spinal nerves – 8 cervical, 12 thoracic, 5 lumbar, 5 sacral and 1 coccygeal

Several dorsal (sensory) and ventral (motor) rootlets combine to form the roots of the spinal nerves- roots and rootlets are either sensory or motor, not both

Spinal nerves are both sensory (afferent) and motor (efferent) and are named/numbered for the intervertebral foramina that they pass through – IV foramen between C1 and C2 has spinal nerve C2

Dorsal roots - afferent / sensory fibers from skin, subcutaneous and deep tissues, and visceraCell bodies in dorsal root ganglia (DRG, spinal ganglia)

Dorsal Ramus – sensory and motor information to skin and true muscles of the back

Ventral roots – efferent / motor fibers to skeletal muscle and presynaptic autonomic fibersCell bodies in the ventral horn of the spinal cord

Ventral Ramus – sensory and motor information to the rest of the trunk and the limbs

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Explain what a dermatome represents and locate / identify important dermatomes

Dermatomes – regions of the skin that are innervated by a single spinal nerve pair

Myotomes – regions of muscle that receive innervation from a single nerve pair

Sclerotome – connective tissue structures innervated by a single spinal nerve pair

Important, representative areas . . .

C2 – back of head C5 – top of shoulder C6 – thumb C8 – pinkie T4 – nipple

T10 – umbilicus L2 – inguinal L4 – knee S1 – sole of foot S5 – anal canal

BRAINSTEM

Midbrain (mesencephalon)

Can be subdivided into a tectum (colliculi), tegmentum (cranial nerve nuclei / pathways) and cerebral peduncles (motor tract)

Tectum – located dorsal to the cerebral aqueduct (between 3rd and 4th ventricles)

Superior Colliculus – vision nucleus associated with visual attention and eye movementsAlso defines the cross sectional location of the Occulomotor Nucleus (CN III)Edinger-Westphal nucleus (pupillary light response and accomidation)

located anterior and medial to CNIII

Inferior Colliculus – auditory nucleus associated with main pathway of auditory informationEar –> cochlear nucleus –> lateral lemniscus -> inferior colliculus –>

(inferior colliculus) –> medial geniculate nucleus -> auditory cortex

Tegmentum – passageway for motor fibers, sensory fibers and houses some cranial nerve nuclei (CN III & CN IV nuclei)

Describe which cranial nerve / cranial nerve nuclei are associated with the midbrain

Occulomotor nerve (CN III) Trochlear nerve (CN IV)

Discuss which cerebrospinal fluid space is associated with the midbrain

Describe the location and contents of the cerebral peduncles

Pons (metencephalon)walnut shaped structure on ventral surface of brainstemFor passing and synapsing tracts involved with muscle movement

Corticospinal tract - cortex to spinal cord Corticopontine tract – cortex to ponsPontocerebellar tract – pons to cerebellum

Describe which cranial nerve / cranial nerve nuclei are associated with the pons & ventral tegmentum

Trigeminal nerve (CN V) Abducens nerve (CN VI)

Facial nerve (CN VII) Vestibulocochlear nerve (CN VIII)

Describe the location and contents of the cerebellar peduncles

Superior cerebellar peduncle Middle cerebellar peduncle Inferior cerebellar peduncle

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Discuss which cerebrospinal fluid space is associated with the pons / cerebellum

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Medulla Oblongata (mylencephalon)Brain’s connection to spinal cordContains motor tracts, some cranial nerve nuclei and proprioceptive nuclei

Pyramidal tracts - medial swellings (pyramidal motor system) on ventral medulla

Olive – ventrolateral swellings (vestibular extrapyramidal system) made by Inferior Olivary Nuclei

Gracile Tubercle – dorsomedial swellings made by gracile nucleus – LE touch, proprioception

Cuneate Tubercle – dorsolateral swellings made by cuneate tubercle – UE touch, proprioception

Describe which cranial nerve / cranial nerve nuclei are associated with the medulla oblongata

Glossopharyngeal nerve (CN IX) Vagus nerve (CN X)

Spinal Accessory nerve (CN XI) Hypoglossal nerve (CN XII)

Discuss which cerebrospinal fluid space is associated with the medulla oblongata

Cerebellum (metencephalon)

Identify the cerebellar lobes and hemispheres

vermis anterior lobe posterior lobe

flocculonodular lobe primary fissure arbor vitae

Discuss the specific functions related to deep cerebellar nuclei

Deep Cerebellar Nuclei – efferent neurons sending axons to thalamus, brainstem or vestibular nuclei

Dentate Nucleus - large lateral nucleus of the superior cerebellar peduncleTo motor and premotor cortex (thalamus) for motor planning

Interposed Nuclei – intermediate nuclei to lateral descending systems for motor execution

Fastigial Nucleus - medial nucleus dorsal to 4th ventricle for medial motor execution

Discuss which cerebrospinal fluid space is associated with the pons / cerebellum

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CRANIAL NERVES Most arise from ventral surface of brain/brainstem

Locate and name the twelve pairs of cranial nerves

Associate the primary origins and target of the cranial fossa of each cranial nerve pair

Categorize the primary activity of each cranial nerve (sensory, motor, or mixed)

Locate where all cranial nerves enter or exit central nervous system (dashed line)

The peripheral target/origin is on the left side of the pageThe bone passage is bold, underlines and italicized (not necessary to re-learn)The cranial nerve is always in the peripheral nervous systemThe central origin/target is on the right side of the page

CN I Olfactory – smell (special sensory) Enters olfactory bulb on inferior (ventral) surface of frontal lobe

CNS

olfactory epithelium cribiform plate of ethmoid bone CN I olfactory bulb

CN II Optic – vision (special sensory) Enters posterior (ventral) part of diencephalon (optic chiasm)

CNS

retina CN II optic canal optic chiasm optic tract lateral geniculate body superior colliculus

CN III Oculomotor – voluntary eye movements (somatic motor) and involuntary eye movement (autonomic motor) Exits brainstem between cerebral peduncles, rostral (ventral) to pons

CNS

occulomotor nucleus CN III superior orbital fissure most extrinsic eye muscles (except sup obl & lat rect)

ciliary ganglion ciliary muscle & iris of eye

CN IV Trochlear - inferomedial directed gaze (somatic motor) Exits DORSAL brainstem caudal to inferior colliculus

CNS

trochlear nucleus CN VI superior orbital fissure superior oblique (eye muscle)

CN V Trigeminal – face, scalp and dura touch / pain (somatic sensory) and masticators (motor) Enters / Exits brainstem lateral (ventral) to pons

Ophthalmic division (V1) – forehead, scalp sensory CNS

orbit / forehead supraorbital notch superior orbital fissure CN V trigeminal sensory nucleus

Maxillary division (V2) – upper jaw sensory CNS

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upper jaw infraorbital foramen foramen rotundum CN V trigeminal sensory nucleusMandibular divison (V3) – lower jaw sensory and masticator motor CNS

lower jaw mental foramen mandibular foramen foramen ovale CN V trigeminal sensory nucleus

masticators mental foramen mandibular foramen foramen ovale CN V trieminal motor nucleus

CN VI Abducens – lateral directed gaze (somatic motor) Exits caudal (ventral) to pons on midline

CNS

abducens nucleus CN VI superior orbital fissure - lateral rectus (eye muscle)

CN VII Facial - muscles of facial expression (somatic motor), taste (special sensory) and watery glands (autonomic / motor) Enters / Exits brainstem caudal to pons (lateral), rostral to medulla

CNS

facial nucleus CNVII internal acoustic meatus stylomastoid foramen muscles of facial expression

pterygopalatine / submandibular ganglia lacrimal, submandibular / sublingual glands

solitary nucleus CNVII stylomastoid foramen tongue tastebuds

CN VIII Vestibulocochlear – hearing / balance (special sensory) Exits brainstem caudal to pons (lateral), rostral to medulla, lateral to facial nerve

CNS

cochlea / vestibular apparatus internal acoustic meatus CN VIII vestibular / cochlear nuclei

CN IX Glossopharyngeal – pharyngeal touch / pain (somatic sensory), taste (special sensory) and parotid gland (autonomic) Enters/ Exits brainstem rostrolateral in medulla, lateral to olive

CNS

tongue tastebuds jugular foramen CN XI solitary nucleus

pharynx jugular foramen CN XI nucleus ambiguus

parotid gland otic ganglion CN XI nucleus ambiguus

CN X Vagus – laryngeal touch / move (somatic sensory /motor), taste (special sensory), thorax viscera (autonomic)

Enters/ Exits brainstem lateral to olive, caudal to glossopharyngeal nerve

CNS

pharynx tastebuds jugular foramen CN X solitary nucleus

larynx (voice) jugular foramen CN X vagal motor nucleus

thoracic organs vagal ganglion CN X vagal motor nucleus22

CN XI Spinal Accessory – shoulder / pharyngeal muscles (somatic motor)

Enters/ Exits brainstem lateral to olive, caudal to vagus nerve CNS

nucleus ambiguus CN XI jugular foramen - pharyngeal muscles, sternocleidomastoid and trapezius

C1-C3 ventral horn CN XI foramen magnum jugular foramen - pharyngeal muscles, SCM and trapezius

CN XII Hypoglossal – intrinsic tongue (somatic motor) Exits between pyramids and olive of medulla oblongata

CNS

hypoglossal nucleus CN XII hypoglossal canal - intrinsic tongue muscles

Identify the cranial nerve pairs containing sympathetic/parasympathetic (autonomic) fibers.

Identify the parasympathetic ganglion associated with each cranial nerve containing autonomic fibers

Oculomotor (CN III) - ciliary ganglion: iris and ciliary muscle of eye

Facial (CN VII) - pterygopalatine ganglion: lacrimal gland Submandibular ganglion: sublingual and submandibular glands

Glossopharyngeal (CN IX) – glossopharyngeal ganglia: pharynx otic ganglion: parotid gland

Vagus (CN X) – vagal ganglia: heart, esophagus, lungs, upper abdominal organs

Other cranial nerve classification

General somatic afferent (GSA) – conscious sensation

General somatic efferent (GSE) – voluntary motor

General visceral afferent (GVA) – organ sensation

General visceral efferent (GVE) – autonomic motor to organs

Special sensory afferent (SSA) – special senses (smell, vision, taste, hearing, balance)

Special somatic efferent (SSE) – branchial arch motor (larynx, lower jaw)

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Representative Reflexes Comprehensive list of over 300 reflexes in Stedman’s Medical Dictionary

Accommodation Reflex (Near Reflex)

Coordinated changes in lens shape, pupil size and eye position (convergence) when changing focal points

Afferent input from CNII lateral geniculate nucleus primary visual cortex visual association cortex

Efferent output from visual association cortex occulomotor nuclei CNIII extrinsic muscles

visual association cortex Edinger-Westphal nuclei CNIII ciliary ganglia pupillary / cilliary muscles

Acoustic Reflex (Attenuation/Stapedius Reflex)

Changes to the tympanic membrane and middle ear ossicles in response to sound intensity

Afferent input from CNVIII ventral cochlear nucleus superior olivary nucleus facial /trigeminal nuclei

Efferent output from facial nucleus CNVII stapedius (selectively reduces low frequency noise)

trigeminal nucleus CNV3 tensor tympani (filters out self-generated noise – voice, chewing)

Baroreceptor Reflex (Baroreflex/Carotid Sinus)

Homeostatic countereffect to a sudden change in blood pressure detected at the aortic arch or carotid sinus

Afferent input from CNIX (sinus) and CN X (arch) nucleus of solitary tract vagal nucleus

Efferent output from vagal nucleus CN X cardiac ganglia heart

Corneal Reflex (Blink Reflex)

Contraction of both eyelids and closure of the palpebral fissure in response to stimulation of the cornea by a foreign object

Afferent input from CNV1 spinal trigeminal nucleus facial nucleus (typically cotton wisp)

Efferent output from facial nucleus CNVII orbicularis occuli

Cremasteric Reflex

Contraction of the spermatic cord lining elicited by light touch of the skin of the superior medial thigh

Afferent input from ilioinguinal nerve ventral horn of spinal cord at L1-L@

Efferent output from L1-L2 alpha motor neurons genital branch of genitofemoral nerve

Crossed-Extension Reflex

Simultaneous & opposite extension of the contralateral limb to stabilize the body in response to noxious stimuli

Works in coordination with the Flexor Reflex

As the left leg flexes and withdraws, the right leg extends and supports the body

Afferent input from δ (delta) fibers of free nerve endings spinal nerve ventral horn interneuron of spinal cord

(multilevel)

Efferent output from alpha motor neurons (ventral horn) several adjacent spinal nerves muscles of the stimulated limb

Efferent output would also cross to contralateral side at level of interneurons and cause muscles of non-stimulated limb

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Gag Reflex

Discomfort and muscular contraction elicited with touch of the posterior tongue and oropharynx

Afferent input from CN IX and CN X nucleus ambiguous + vagal nucleus

Efferent output from nucleus ambiguous + vagal nucleus CN IX & CN X pharyngeal muscles & soft palate

(stylopharyngeus, glossopharyngeus, tensor/levator veli palatine, constrictors)

Flexor Reflex (Withdrawal Reflex)

Sudden removal of extremity in response to noxious (hot/sharp) cutaneous stimuli

Afferent input from δ (delta) fibers of free nerve endings spinal nerve ventral horn interneuron of spinal cord

Efferent output from alpha motor neurons (ventral horn) several adjacent spinal nerves muscles of the stimulated limb

Long Loop Reflex

Any reflex that mediates responses via the cerebral cortex

Examples would include accommodation reflex and regulating the contractions in distal muscles (precise voluntary control)

Plantar Reflex (modified deep tendon reflex)

Flexion of the toes in response to the sole of the foot being stroked with a blunt object from heel to the big toe

Afferent input from Ia fibers of muscle spindle plantar nerves ventral horn of spinal cord at S1

Efferent output from S1 alpha motor neurons plantar nerves muscles containing stimulated spindle

Babinski reflex normally occurs in infants and occurs pathologically in cerebral injury or disease

This results in a fanning of lateral toes and dorsiflexion of big toe.

Occulocephalic Reflex (Doll’s Head Eye Movements)

Contraction of the extraoccular muscles to keep both eyes pointed in the same forward direction in relation to the trunk

Head motion to the right causes eye motion to the left

Three sources of afferent input . . .

Afferent input from CNII lateral geniculate nucleus visual cortex occulomotor nuclei

Afferent input from neck muscle spindles & GTI cervical spinal nerves ventral horn of spinal cord MLF

Afferent input from CN VIII vestibular nuclei medial longitudinal fasciculus (MLF) occulomotor nuclei

Efferent output from occulomotor nuclei CN III, IV, & VI extraoccular muscles

Pupillary Light Reflex (Direct = ipsilateral, Consentual = contralateral)

Rapid constriction of both pupils (sphincter papillae contraction) in response to light

Afferent input from CNII lateral geniculate nucleus pre-tectal nucleus (superior colliculus)

Efferent output from pre-tectal nucleus Edinger-Westphal nuclei CNIII ciliary ganglia sphincter pupillae muscles

Salvatory Reflex

Increased secretions of salivary glands in response to food in oral cavity

Afferent input from CNV3(touch) spinal trigeminal nuclei facial nucleus

Afferent input from CNVII, CNIX, CNX (taste) nucleus of solitary tract facial nucleus

Efferent output from facial (salivatory) nucleus CNVII submandibular/sublingual glands

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Stretch / (Deep) Tendon Reflex (Myotatic Reflex)

Jerking of the limb when a muscle’s tendon is struck while the peripheral extremity is relaxed

Afferent input from Ia fibers of muscle spindle spinal nerve ventral horn of spinal cord at the same level

Efferent output from alpha motor neurons spinal nerve muscles containing stimulated spindle

Ankle-jerk (Calcaneal / Achilles) Reflex uses the tibial nerve (S1) to contract gastrocnemius and soleus

Biceps Reflex uses the musculocutaneous nerve (C5)

Brachioradialis Reflex uses the radial nerve (C6)

Jaw-jerk Reflex uses the trigeminal nerve (CNV3) to contract temporalis and masseter muscles in response to chin tap

Knee-jerk (Patellar) Reflex uses the femoral nerve (L4) to contract quadriceps muscles to extend leg at knee

Triceps Reflex uses the radial nerve (C7)

Superficial Abdominal Reflex

Contraction of the abdominal muscles elicited by quickly stroking (lateral to medial, towards the umbilicus) the skin

Abdomen deflects toward the stimulus

Afferent input from intercostal (T8-T11) and subcostal nerves spinal nerve ventral horn of spinal cord

Efferent output from alpha motor neurons spinal nerve intercostal and subcostal nerves abdominal

obliques/transversus

Swallow Reflex

Wavelike coordinated contraction of pharyngeal and esophageal muscles in response to food/drink in pharynx

Afferent input from CN IX and CN X nucleus ambiguous + vagal nucleus

Efferent output from nucleus ambiguous + vagal nucleus CN IX & CN X pharyngeal muscles & soft palate

(stylopharyngeus, glossopharyngeus, tensor/levator veli palatine, constrictors)

Vestibulooccular Reflex

Gaze can remain fixed on an object even though the head is moving or being moved (more than just visual tracking)

Afferent input from CN VIII vestibular nuclei medial longitudinal fasciculus occulomotor nuclei

Efferent output from occulomotor nuclei CN III, IV, & VI extraoccular muscles

Vomit Reflex

Retrograde movement of stomach contents up the esophagus into the pharynx, closure of the epiglottis and

contraction of abdominal muscles (enhanced gag reflex)

Afferent input from CN IX and CN X nucleus ambiguous + vagal nucleus

Efferent output from nucleus ambiguous + vagal nucleus CN IX & CN X pharyngeal muscles & soft palate

Efferent output from alpha motor neurons spinal nerve intercostal and subcostal nerves abdominal

obliques/transversus

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INFANT REFLEXES (disappear or change in adults)

Babinski Reflex (L5-S1)

Fanning of lateral toes and dorsiflexion of the big toe in response to stroking the sole of the foot

Normally disappears between 1-3 years of age

Considered indicative of central nervous system disease (corticospinal damage) after 14-15 months of age

Uses same nerves as Ankle-jerk Reflex (tibial nerve)

Galant Reflex

Rotation of the upper body towards one side as that side of the back is stroked

Moro Reflex

Fear response to sudden loud noise or sensation of being dropped

results in symmetric spreading of arms and subseqeuent recoil of limbs often followed by crying

Palmar Grasp Reflex

Closing of the hand and flexion of the fingers in response to stimulus in the palm of the hand

Rooting Reflex

Pursing of lips and rotation of head towards stimulus in response to rubbing or touch of corner of mouth or cheek

Normally seen in first few months of life

Afferent input from CNV2/V3 spinal trigeminal nuclei facial nucleus + nucleus ambiguus

Efferent output from facial nucleus CNVII orbicularis oris

Efferent output from nucleus ambiguus CN XI sternocleidomastoid and trapezius

Vesicovesical Reflex

Stretch of the urinary bladder wall causes detrusor (voiding muscles) to contract

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LAB 3: Visual, Auditory and Other Systems VISUAL SYSTEM

EYE

Identify the structures associated with the eye

orbicularis oculi palpebrae tarsal glands conjunctiva caruncle

lacrimal gland lacrimal sac nasolacrimal duct plica semilunaris

Discuss the extrinsic eye muscles, listing attachments, innervation and actions of the muscles

Extrinsic Eye Muscles

Muscle Origin Insertion Innervation Blood Supply Action

Superior Rectus Common tendinous ring

Superior sclera Occulomotor N (CN III)

Ophthalmic A Elevate gaze

Inferior Rectus Common tendinous ring

Inferior sclera Occulomotor N (CN III)

Ophthalmic A Depress gaze

Medial Rectus Common tendinous ring

Medial sclera Occulomotor N (CN III)

Ophthalmic A Adduct gaze

Lateral Rectus Common tendinous ring

Lateral sclera Abducens N(CN VI)

Ophthalmic A Abduct gaze

Inferior Oblique Anterior medial floor of orbit

Posteolateral sclera

Occulomotor N (CN III)

Ophthalmic A Gaze sup/latExtorsion of eye

Superior Oblique Body of Sphenoid Superolateral sclera

Trochlear N(CN IV)

Ophthalmic A Gaze inf/latIntorsion of eye

Levator Palpebrae Superioris

Lesser wing of Sphenoid bone

Tarsal plate ofsuperior eyelid

Occulomotor N (CN III)

Ophthalmic A Elevate upper eyelid

To shift gaze superior/medial, contract superior rectus & medial rectus

To shift gaze inferior/medial, contract inferior rectus & medial rectus

To shift gaze superior/lateral, contract inferior oblique, superior rectus & lateral rectus

To shift gaze inferior/lateral, contract superior oblique, inferior rectus & lateral rectus

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Gilroy Atlas of Anatomy, p 508

Define the three layers of the eye and the significant structures associated with each

Sclera / Cornea

cornea optic nerve scleral venous sinus (Schlemm) limbus

Choroid Layer

ciliary body ciliary muscles suspensory ligaments (zonules)

lens iris / pupil sphincter / dilator pupillae

ora serrata aqueous humor anterior chamber posterior chamber

vitreous humor

Retina

fovea centralis macula lutea optic disc retinal arteries pigment epithelium

Optic Nerve – mainly afferent myelinated axons in single bundle exiting posterior eyeball (ipsilateral)

Optic Disk – where axons of retinal ganglion cells leave eyeball and enter optic nerve

Sclera – white dense connective tissue (type II collagen) support for eyeball

Choroid – vascular layer of eye, bringing blood to sclera and outer neural retina

Pigment Epithelium – dark tissue layer between sclera and neural retina to support photoreceptors (phagocytosis)

Retina – nervous tissue part of eye for detection of light

Lens – internal transparent connective tissue structure important for focussing light on photoreceptors

Iris – colored part of eye that acts as a diaphragm and is part of the choroid layer

Ciliary muscle – ring-shaped muscle at margin of neural retina that coordinates lens shape

Suspensory ligaments – connective tissue connections from lens to ciliary muscles to support lens

Cornea – transparent connective tissue in anterior eye

Vitreous humor (body) – posterior transparent jelly-like support for eyeball

Aqueous humor – transparent fluid of anterior/posterior chambers important for nourishment of cornea and lens

Lacrimal gland – purely serous gland located superolateral to eye that makes tears

Discuss accomodation and how the lens changes shape and produces focal changes - seems counterintuitive

ciliary contraction ligaments loosen fat lens near objects

ciliary relaxation ligaments tighten skinny lens far objects

Be able to trace the arterial blood flow from the aortic arch to the cells of the retina

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Central Visual Pathways: Be able to describe and locate the following…

Optic Chiasm – crossing of afferent axons from both eyes (~50%) to produce unified visual fields

Optic Tract – right/left afferent axons from a single visual field passing to lateral geniculate nucleus (thalamus)Right visual field represented in left lateral geniculate thalamus from both eyes

Lateral Geniculate Nucleus – posterolateral part of thalamus associated with vision from a single visual fieldInput from both eyes and superior colliculus

Laminated structure so that each visual field’s input remains separate (not binocular)

Primary Visual Cortex – posteromedial part of occipital lobe associated with vision (binocular)Input from lateral geniculate nucleus and other visual nuclei

Located specifically within the calcarine sulcus

Quick Visual Experiments: Find a partner and attempt

Pupillary Light Reflex:Constriction of iris / pupil due to increased illumination

What is the effect on single eye illuminated?

What is the effect of illumination on the contralateral eye (non-illuminated)?

What cranial nerves are associated with this phenomenon?

Optokinetic ReflexHave partner sit on a chair with wheels and have theirs eyes focus on the lock mechanism of a locker

Push partner down hall near lockers being extremely CAREFUL to maintain balance for your partner.

After 10 seconds, stop pushing and monitor partner's eyes - Be sure to brace partner so that they don’t fall.

Note the direction of the quick and slow phases of the eye motion.

Have partner describe what they are experiencing.

In which direction do the eyes move rapidly? Move slowly?

What part of the visual system has been activated (specifically)?

Accomodation:Change of lens shape, pupil diameter and orientation of gaze due to changes in viewing distance

What is the effect of close visual stimuli on the pupil? lens? on position of gaze?

What is the effect of distant visual stimuli on the pupil? lens? on position of gaze?

After-ImageOver-stimulation of photoreceptors will result in a residual image. Adapt eyes to bright light and then close eyes or

change views.

Why does the original after-image occur?

Why does the second negative after-image occur?

How does color affect this effect and do different colors produce different after-images?

The bright after-image is caused by continued stimulation of photoreceptors.

After a short time, a negative after-image of the first after-image will appear due to bleaching of photoreceptors.

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AUDITORY / VESTIBULAR SYSTEM

EAR

Locate the structures associated with the external ear

external auditory meatus tympanic membrane auricle / pinna auditory canal

helix antihelix tragus anti-tragus

scapha cymba triangular fossa

Auricle / Pinna – elastic cartilage based external ear designed for funneling sound into skull

External Auditory Meatus – outer hole in the skull through which sounds pass to reach eardrum

Tympanic Membrane (eardrum) – connective tissue sheet that vibrates due to sound waves

Connected to malleus to transmit sound to inner ear

Locate the structures of the middle ear – within temporal bone

ossicles malleus (hammer) incus (anvil) stapes (stirrup)

pharyngeotympanic (auditory) tube stapedius (CN VII) tensor tympani (CN V3) chorda tympani

Ossicles – middle ear bones (3)

Malleus (hammer) - attaches tympanic membrane to incus

Incus (anvil) - attaches malleus to stapes

Stapes (stirrup) – attaches incus to oval window of inner ear

Tensor tympani – changes the dynamics of the eardrum to allow for listen for specific sounds

Stapedius – limits motion of stapes to alter oscillatory range and allow for filtering out background sound

Chorda typmani (CN VII) for innervation of mandibular salivary glands and taste

Pharyngeotympanic tube (auditory / Eustachian tube) for equalizing pressure between outer and inner ear

Locate the structures of the inner ear – within petrous part of temporal bone

cochlea semicircular canals (ant/post/lat)

ampullae utricle saccule

Cochlea

scala vestibuli scala tympani scala media (cochlear duct)

vestibular membrane basilar membrane tectorial membrane oval window round window spiral organ of Corti

modiolus helicotrema

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Cochlea – coiled auditory structure where pressure waves are transferred into nerve impulses

Vestibule – sac like structure connected to cochlea and semicircular canals

Important for detecting linear acceleration

Semicircular Canals – three half-circle tubes connected to the vestibule

Important for detection of angular acceleration

Identify the blood supply to the inner ear as the labrynthine artery

Central Auditory / Vestibular Pathway:

Be able to describe and locate the following…

1 - Cochlea / Vestibule / Semicircular Canals send afferent information to the cochlear or vestibular nuclei

2 - Cochlear / vestibular nuclei sends information bilaterally to a variety of nuclei including . . .

superior olive, inferior colliculus and lateral lemniscus

also to the trapezoid nucleus and reticular formation

3 – Superior olive sends information to the lateral lemninscus and inferior colliculus

4 - Inferior colliculus sends information to medial geniculate nucleus (posterior lateral thalamus)

5 - Medial geniculate nucleus sends information to the auditory cortex (superior temporal lobe)

Discuss how sound is transmitted into nerve impulses, tonotopical and intensity coding

BASE = intense/high frequency sound APEX = low frequency sounds

Volume gauged by # action potentials/secondFrequency (pitch) gauged by which receptors responding (base or apex)

Quick Vestibulocochlear Experiments: Find a partner and attempt

Weber’s Test – to distinguish nerve deafness from conduction deafness

Base of vibrating tuning fork is applied to midline forehead of partner.

Partner determines if sound is heard in the midline or if it is localized in one ear (midline normal).

If nerve damaged bilaterally, there will be no difference between sound conduction between bone and air.

If the nerve is damaged unilaterally, there should be a deficiency on the affected side

If bone conduction is the problem, the sound would seem exaggerated on the affected side

Rinne’s Test - also to distinguish nerve deafness from conduction deafness

Base of vibrating tuning fork is applied over the mastoid process (bone inferior to ear) of the skull.

When it can no longer be heard, the still vibrating fork is held in front of ear.

Sound should again be detectable (air conduction more sensitive than bone conduction normally).

If bone conduction is the problem, then sound by air would be diminished compared to sound by bone.

If nerve damage is the problem, then all sound would be diminished, although air sounds would be better

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VestibuloOcular Reflex

Have partner stand with eyes eyes fixed on single object (Spot).

Spin partner (clockwise/right) being extremely CAREFUL to maintain balance for your partner.

After 10 seconds, stop spinning and monitor partner's eyes - Be sure to brace partner so that they don’t fall.

Note the direction of the quick and slow phases of the eye motion.

Have partner describe what they are experiencing.

In which direction do the eyes move rapidly? Move slowly?

What part of the vestibulocochlear system has been activated (specifically)?

Autonomic Nervous System

Composed of parasympathetic, sympathetic and enteric nervous systems

Enteric nerves – coordinate peristaltic movements of the digestive system. NOT the rate, just motion

Parasympathetic nerves – involved with long-term survival of the personLocated in cranial and sacral regions of the central nervous systemInvolved with pupillary light reflex (CN III), salivary gland secretion (CN VII and IX)

and viscera metabolism (CN X)Also associated with urogenital system and reproduction

Sympathetic nerves – involved with the fight or flight responseLocated in thoracic and lumbar regions of the central nervous systemAntagonistic to parasympathetic system on same organs.

Does NOT use cranial nerves – relies instead on cervical ganglia (sympathetic chain)

Endocrine

Pituitary gland – located inferior to diencephalonstorage facility for hormones produced in the hypothalamus (post) or synthesized there (ant)connected to diencephalon/hypothalamus by infundibulum (pars tuberosa of neurohypophysis)

Hypothalamus – anterior diencephalon Contains numerous nuclei that are difficult to distinguish, but include…

Paraventricular Nucleus – make anti-diuretic hormoneSuprachiasmatic Nucleus – involved with circadian rhythymSupraoptic Nucleus – makes oxytocin (reproductive contractions)

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LIMBIC SYSTEM

Hippocampal formation – medial temporal lobe associated with memory

Amygdala – anteromedial temporal lobe (near olfactory bulb) associated with emotion

Fornix – hippocampus connection to mammillary bodies

Mammillary bodies – posterior to pituitary, small mounds / nuclei send info to the cingulate gyrus

Cingulate gyrus – associated with the perception of pain but also communicates info to cortex

Follow information streams from amygdala to hippocampus to fornix

to mammillary bodies to cingulate gyrus to enterorhinal cortex to amygdala (Circuit of Papez)

amygdala hippocampus fornix mammillary bodies /\ |

| || \/

Parahippocampal/entorhinal cortex cingulate gyrus anterior nucleus of thalamus

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Neuroscience

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