UNIVERSITY OF NEW ENGLAND
College 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 material
Safety glasses for splash protection are available in the lab
Gloves will be provided; please try to limit use to ~1 pair / session
Long hair must be tied back, away from the face. Long necklaces should be removed
Contact Lenses are NOT advised,
as they are permeable to volatile compounds and may result in injury
Students 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 times
Any student who damages a model will be held financially responsible
Model 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 blackboards
The reason that you wear gloves is to protect yourself
Handling “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 slippery
To 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 solution
Help 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 hands
Wash 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 pregnancy
have 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
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 (4 th 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
(C5-T1)
(T12-S3)
cervical plexus (ansa cervicalis)
sympathetic chain
(C1-C4)
CEREBRAL CORTEX
(Telencephalon)
Longitudinal Fissure separates RIGHT and LEFT hemispheres
FRONAL LOBE: Identify the following structures
lateral sulcus
frontal gyri
central sulcus
pre-central gyrus (primary motor cortex)
(pre-motor cortex)
(pre-frontal cortex)
central sulcus – separates motor (anterior) from sensory (posterior) cortex
Also 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 sulcus
Disproportionate body map (homunculus) superimposed on gyrus
Oriented 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 hemisphere
Associated 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 sulcus
Sensory homunculus superimposed on gyrus
Oriented 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 lobe
Easily 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 gyrus
Tonotopic map of auditory space – low tones different region from high tones
Wernicke’s Area – superior temporal gyrus (posterior part) of left hemisphere
Associated with language comprehension
uncus – inferior medial temporal lobe – contains amygdala and hippocampus
hippocampus – medial temporal lobe
Associated 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 diencephalon
Includes pineal gland and habenular nuclei (eating behavior)
hypothalamus – inferior part of diencephalon
Infundibulum connects to pituitary gland
Includes nuclei to help regulate body temperature, fluid osmolarity
thalamus – egg-shaped mass of nuclei in lateral walls of diencephalon
Sensory switchboard / relay for information going to cortex
posterior to basal ganglia, superior to internal capsule
Various nuclei make up thalamus, each sending information to specific regions
Medial Geniculate Nuclei – auditory information to auditory cortex
Lateral Geniculate Nuclei – visual information to V1
Identify the structures of the hemi-sected brain:
corpus callosum
septum pellucidum
cingulate gyrus
parahippocampal gyrus
optic nerve/chiasm
uncus
corpus callosum – C-shaped structure connecting frontal, parietal, temporal and occipital lobes of cortex
mylenated commissure between left and right hemisphere
Largest 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 pallidus
Major 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
pons
sup/inf/mid cerebellar peduncles
cerebral aqueduct
medulla oblongata
pyramids
cuneate/gracile tubercle
olive
superior / inferior colliculi
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
(Metencephalon)
Gyri called folia because of leaf-like appearance
(extrapyramidal motor area)
Identify the structures of the cerebellum
vermis
anterior lobe
sup/inf/mid cerebellar peduncles
posterior lobe
flocculonodular lobe
primary fissure
arbor vitae
vermis – dorsal central cerebellum – adjacent to occipital cortex
Receives afferent sensory information from spinal cord (spinocerebellar tract)
anterior lobe – superior cerebellum, separated from posterior lobe by primary fissure
Receives proprioceptive information from afferent fibers in spinal cord
posterior lobe – makes the bulk of the cerebellum – inferior to primary fissure
Receives efferent motor information from the cerebral cortex / pons
flocculonodular lobe - lateral to cerebellar attachment (cerebellar peduncle) to brainstem
Receives 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 Arteries
Enter skull via carotid canal of temporal bone (right and left)
Each branches into…
ophthalmic artery – orbital muscles, glands and retina
anterior 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 plexus
frontal, 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
choroidal arteries
basilar artery
cerebral arteries
ophthalmic arteries
communicating arteries
perforating arteries (lenticulostriate & thalamotuberal arteries)
cerebellar arteries
labyrinthine arteries
vertebral arteries
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Cerebral Arterial Circle (of Willis)
Anastomosis of cerebral arteries
anterior cerebral arteries joined by anterior communicating artery
posterior cerebral arteries joined to internal carotid by posterior communicating arteries
Vertebral Arteries
Pass through foramen magnum and join together to form basilar artery
Single branch …
posterior inferior cerebellar artery (PICA) – blood to inferior cerebellum (flocculonodular lobe)
Basilar Artery
Ventral to pons within the posterior cranial fossa (anterior to foramen magnum)
Branches include…
anterior inferior cerebellar arteries (AICA) – blood to middle cerebellum
labyrinthine arteries – blood to inner ear
pontine arteries – blood to pons
superior cerebellar arteries – blood to superior cerebellum
posterior 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
interventricular foramen (of Monro)
cerebral aqueduct
4th ventricle
median (Magendie) aperture &
lateral (Luschka) apertures
CSF is created by the choroid plexus located in each of the ventricles of the brain
It protects the brain by providing cushion
It flows from…
1 - lateral ventricles in cerebral hemispheres
2 – to 3rd ventricle located in the diencephalon (between right and left thalami)
3 – through cerebral aqueduct deep to superior and inferior colliculi
4 – into 4th ventricle located between pons/medulla oblongata and cerebellum
5 – enters central canal of spinal cord or sub-arachnoid space around brain
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subarachnoid space/ cisterns
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 pons
At 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 oblongata
Largest CSF pool in head
Superior (Quadreminal) cistern – between corpus callosum and cerebellum
Posterior 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 meningeal
Dural sinuses which drain blood from the brain reside between these two layers
Arachnoid Mater - intermediate membrane / mesh of fibers (trebeculae)
Location of large blood vessels
Sub-Arachnoid space filled with cerebrospinal fluid
Pia Mater - internal, vascular memebrane adjacent to brain
Follows sulci and gyri intimately
Does 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
funiculus / fasciculus
anterior median fissure
posterolateral sulci
dorsal root ganglia
dorsal / ventral rami
cauda equina
terminal filament
medullary cone
lumbar cistern
denticulate ligaments
cervical / lumbar enlargement
commissure
dorsal / ventral root
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 surfaces
Extends from foramen magnum (occipital bone) to L2 (45cm long) - upper 2/3 of the vertebral column
Cord 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 coccyx
holds spinal cord in place at inferior end of vertebral column
dural sac (dura inferior to medullary cone) anchors to filium terminale
Anterior Longitudinal (Median) Fissure - ventral fissure between RIGHT and LEFT sides of the spinal cord
Provides 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 information
Contains cell bodies of interneurons – sending info up to brain, to ventral horn and commissural
Connected to dorsal root via Lissauer’s Tract
Ventral Horn – Associated with motor function / efferent information
Contains 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 system
Motor neuron cell bodies for sympathetic (fight or flight) response
Posterior Funiculi – between the right and left dorsal horns
Associated with proprioception and touch sensory information travelling to post-central gyrus
In bundles called posterior columns or fasciulus gracilis / cuneatus
Fasiculus Gracilis – T6 inferior sensory information - medial
Fasiculus 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 horns
Associated 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 terminale
superficial 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 cord
creates the filium terminale within the lumbar cistern
makes 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 space
Superiorly 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 viscera
Cell 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 fibers
Cell 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 movements
Also 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 information
Ear –> 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 brainstem
For passing and synapsing tracts involved with muscle movement
Corticospinal tract - cortex to spinal cord
Corticopontine tract – cortex to pons
Pontocerebellar 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
Discuss which cerebrospinal fluid space is associated with the pons / cerebellum
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Medulla Oblongata (mylencephalon)
Brain’s connection to spinal cord
Contains 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 peduncle
To 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 page
The bone passage is bold, underlines and italicized (not necessary to re-learn)
The cranial nerve is always in the peripheral nervous system
The 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
upper jaw  infraorbital foramen  foramen rotundum  CN V   trigeminal sensory nucleus
19
Mandibular 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 nucleus
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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)
21
Comprehensive list of over 300 reflexes in Stedman’s Medical
Representative Reflexes
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
22
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
24
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
25
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
Superior sclera
Elevate gaze
Ophthalmic A
Depress gaze
Ophthalmic A
Adduct gaze
Ophthalmic A
Abduct gaze
Ophthalmic A
Levator Palpebrae
Superioris
Lesser wing of
Sphenoid bone
Occulomotor N
(CN III)
Occulomotor N
(CN III)
Occulomotor N
(CN III)
Abducens N
(CN VI)
Occulomotor N
(CN III)
Trochlear N
(CN IV)
Occulomotor N
(CN III)
Ophthalmic A
Superior Oblique
Common tendinous
ring
Common tendinous
ring
Common tendinous
ring
Common tendinous
ring
Anterior medial
floor of orbit
Body of Sphenoid
Gaze sup/lat
Extorsion of eye
Gaze inf/lat
Intorsion of eye
Elevate upper
eyelid
Inferior Rectus
Medial Rectus
Lateral Rectus
Inferior Oblique
Inferior sclera
Medial sclera
Lateral sclera
Posteolateral
sclera
Superolateral
sclera
Tarsal plate of
superior eyelid
Ophthalmic A
Ophthalmic A
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
Gilroy Atlas of Anatomy, p 508
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Define the three layers of the eye and the significant structures associated with each
Sclera / Cornea
cornea
optic nerve
scleral venous sinus (Schlemm)
ciliary muscles
suspensory ligaments (zonules)
iris / pupil
sphincter / dilator pupillae
aqueous humor
anterior chamber
limbus
Choroid Layer
ciliary body
lens
ora serrata
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 field
Input 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 Reflex
Have 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-Image
Over-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
scala vestibuli
scala tympani
scala media (cochlear duct)
vestibular membrane
basilar membrane
tectorial membrane
oval window
round window
spiral organ of Corti
modiolus
helicotrema
Cochlea
29
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/second
Frequency (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 person
Located in cranial and sacral regions of the central nervous system
Involved 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 response
Located in thoracic and lumbar regions of the central nervous system
Antagonistic to parasympathetic system on same organs.
Does NOT use cranial nerves – relies instead on cervical ganglia (sympathetic chain)
Endocrine
Pituitary gland – located inferior to diencephalon
storage 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 hormone
Suprachiasmatic Nucleus – involved with circadian rhythym
Supraoptic 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
/\
|
|
Parahippocampal/entorhinal cortex
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

fornix

cingulate gyrus
mammillary bodies
|
|
\/
 anterior nucleus of thalamus
Neuroscience
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