Neuroanatomy Flashcards
What spinal level does the spinal cord end in children and adults, the subarachnoid space end?
Spinal cord: Adults L1/L2, Children L3
Subarachnoid space:
What are the spinal levels of the cervical and lumbosacral enlargement?
Cervical C4-T1 Lumbosacral (L2-S3) (roughly the level of the brachial plexus (C5-T1) and the lumbosacral plexus
Is the epidural space in the spinal cord true? How many layers of dura are on the spinal cord?
yes…vs. brain it is a potential space
One layer of dura continuous with the meningeal dura of the brain.
Which space are the spinal vessels suspended in?
The subarachnoid space, which is also filled with CSF. The posterior paired vessels supply the posterior 1/3 of the cord including the PCML. The anterior artery supplies the anterior 2/3
What meningeal covering is the filum terminale a part of?
pia
Which spinal levels have more grey matter in the cord? Which have more white matter?
Cervical and lumbar have more gray matter because they innervate the limbs, so extra cell bodies. More white matter as you move rostrally.
How many spinal nerves are there?
31
What spinal levels are SNS? PNS?
SNS: T1-L2 PNS: S2-S4
Where is the spinothalamic tract? What information does it carry? How many neurons does it involve?
In the anterolateral part of the lateral column. It carries crude touch, pain and temperature. It is a three neuron tract with cell bodies in the DRG, the subtantia gelatinosa and the thalamus
How does temperature information get from the skin to the brain?
Sensory neuron (cell body in DRG) enters the cord in Lissauer’s fasciculus, travels up/down 1-2 levels, synapses with another neuron in the substantia gelatinosa (dorsal horn) then this new neuron crosses over in the anterior white commisure and enters the spinothalamic tract. This goes up to the thalamus (ventral posterolateral (VPL)), synapses in the thalamus then goes to the post-central gyrus
Which nerve endings convey touch?
Meissner’s corpuscles (papillary dermis- light touch) Pacinian corpuscles (reticular dermis-deep pressure and vibration) Ruffini endings Merkel endings (stratum basal- vibration)
Define nucleus
A discrete collection of cell bodies within the CNS
How does light touch and proprioception information get to the brain?
Sensory neurons (cell body in DRG) from lower limb enter the fasciulatus gracile (more medial) and the upper limb enter the fasciculatus cuneate (more lateral). Travel up the spinal cord and synapse in the cuneate and gracile nuclei of the medulla. Cross over (decussate) as internal arcuate fibers then. Move up through the medial lemniscus of pons. Synapse in the ventral posterolateral nucleus of the thalamus, continue on to the post-central gyrus
What is somatotopic organization and what are the general principles?
Somatotropic organization is essentially where the fibres from one part of the body travel in the spinal cord.
Cervical fibres are always closest to the gray matter.
Fibers entering (sensory) first are more medial (makes sense, like seven-layer dip)
Fibers exiting (motor) first are closer to gray (doesn’t make sense…but take those motor fibers and turn that seven-layer dip upside down…but sorta makes sense because dem axons have to get into the anterior horn and synapse first.)
What are the two different parts of the corticospinal tract and what does each part do?
Anterior CST: postural Lateral CST: limb movements
What is the blood supply of the corticospinal tract?
both anterior and posterior spinal arteries
What does the cavity of the neural tube develop into?
The ventricles
Are cranial nerves part of the CNS or PNS?
PNS
Where does the CNS make its 90 degree bend, and what does that mean for orientation?
At the midbrain-diencephalon junction.
What is the spacing of the ventricles in the anterior vs. posterior forebrain?
They are wider apart in the anterior then move close in the posterior pole
What are the parts of the CNS?
- Forebrain
- Telencephalon: Cerebrum (cortex, basal ganglia etc..)
- Diencephalon: thalamus, hypothalmus, subthalamus
- Midbrain
- Brain stem
- Cerebellum
- Pons
- Medulla
- Spinal cord
What fissures separate the cerebral lobes? What spearates the occipital lobe?
Hemispheres from each other: longitudinal fissure
Frontal from temporal and parietal: central sulcus
Temporal from parietal + frontal : lateral sulcus (AKA Sylvian fissure)
Parietal from occipital: parieto-occipital sulcus (AKA transverse occipital fissure)
Limbic (AKA cingulate gyrus) from rest: cingulate sulcus
Calcarine fissure: splits occipital into superior (cuneate) and inferior (lingual) lobes
Where are:
- Midbrain (tectum, colliculi, cerebral peduncles, interpeduncular fossa, mammilary bodies)
- Pons (superior, inferior and middle cerebellar peduncles)
- Medullar (pyramids, olives, pyramidal decussation, fasciculus gracilis and cuneate, nucleus gracillis and cuneate)
- Cerebellum (hemispheres, peduncles, vermis)
What is the internal capsule? How to recognize it on an horizontal section? What structures does it run between?
A tract containing the corticospinal tract. These fibers come from the precentral gyrus (gray matter), into the corona radiata (white matter) then course lateral to the thalamus and caudate nucleus but medial to the putamen and globus pallidum. They look like a V on a horizontal section. The internal capsule contains 3 parts: anterior, genu and posterior.
What are the basal gnaglia?
Caudate
Putamen
Globus pallidus
subthalamic nucleus
substanstia nigra
What the interthalamic adhesion?
Nerves that connect the two halves of the thalamus. Only found in 70-80% of humans, so probably not that important.
What are the potential spaces in the brain coverings?
- epidural (between the periosteal dura and the skull)
- subdural (between the meningeal dura and the arachnoid layer)
The subarachnoid is a real space filled with CSF
Trace the path of CSF from production to reabsorption
- Produced by ependymal cells of the choroid plexus in the ventricles. Flows from lateral to third via foramen of Monroe. From third (between thalamic lobes) to four (between pons and cerebellum) via the cerebral aqueduct. CSF leaves the fourth ventricle via the lateral foramen of Luschka and the midline foramen of Magendie to the subarchnoid space of the brain and spinal cord. It is reabsorbed by subarachnoid granulations in the superior sagittal sinus and enters venous circulation. There are also some cisterns where it tends to collect, like the lumbar cistern (where a lumbar puncture would happen)
What is the basic difference between cerebral edema vs. hydrocephalus
cerebral edema: brain cells swell, BBB becomes more permeable from inflammation
hydrocephalus: increase in CSF (in the ventricles… e.g. inflammation in bacterial meningitis means subarachnoid granules don’t resorb as well)
Both result in increased ICP
Where roots, rami, the spinal nerve and the sympathetic chain?
Where is the denticulate ligament?
Between the posterior and anterior roots
At which site is the needle inserted for lumbar puncture?
- L3/L4 or L4/L5 space
- interilliac crest line intersects L4 spinous processes
What are the major ascending and descending tracts in the spinal cord and where are they found?
What are the two main somatosensory pathways, which tracts do they contain and what modalities do they carry?
Anterolateral system:
- spinothalamic tract
- pain, temperature, non-discriminative touch
Posterior column- medial lemniscal pathway
- fasiculus gracilis and cuneatus
- discriminative touch, proprioception, vibration
What are the receptors involved in proprioception?
Muscle spindle, golgi organs, joint receptors (?)
What is the difference between conscious and unconcious proprioception?
Concious is carried via FG/FC to the cortex, unconcious is carried via the Clarke nucleus to the spinocerebellar tract to the cerebellum.
What are the four spinocerebellar tracts,what kind of information to they carry with regards to unconscious proprioception and where do they enter the cerebellum?
(Important to know that they are all ipsilateral)
- Cuneocerebellar tract
- Upper limbs (above Clark nucleus)
- Inferior cerebellar peduncle
- only proprio
- Ventral spinocerebellar tract
- motor and proprio
- lower limbs
- superior peduncle
- Dorsal spinocerebellar tract
- lower limbs (?) (goes through Clark nucleus)
- Inferior cerebellar peduncle
- only proprio
- Rostral spinocerebellar tract
- Carry motor and proprio information
- Superior peduncle
Which parts of the medulla are open and closed?
Rostral = open
Caudal= closed
What spinal levels have a lateral horn? What tract and what kind of fibers travel there?
Spinal segments with autonomic output: T1-L2 (SNS) and S2,3,4 (PNS)
The interomediolateral cell column
A lesion that cut off the bladder above S2,3,4 would results in what kind of symptoms?
Open (rostral medulla)
Closed (caudal) medulla
Rostral pons
caudal pons
Corticobulbar output is _____ except to the genioglossus it is _________
Bilateral, contralateral
What do the superior and inferior colliculi do (generally)?
Superior: vision
Inferior: scent
Where does each cranial nerve emerge?
I: inferior surface of brain
II: inferior surface of brain
III: interpeduncular fossa (anterior midbrain)
IV: caudal to inferior colliculus (posterior midbrain)
V: basal pons at junction of middle cerebellar peduncle
VI: groove between medulla and pons, medially
VII: groove between medulla and pons, laterally (pontocerebellar angle)
VIII: groove between medulla and pons an cerebellum (more lateral than VII)
IX, X: posterior to olive (in numerical order top to bottom)
XI: upper cervical spinal cord (C1-C5)
XII: anterior to olive
Is CSF produced or an ultrafiltrate?
It is produced by cells of the choroid plexus found in the ventricles, folded into a double layer. It’s composition is identical to the ECF. Compared to plasma it is lower in protein, higher in PCO2 (therefore more acidic). Cell counts, protein and glucose can all indicate pathology, but I don’t think there is a formal criteria, like Light’s criteria for pleural effusion, to diagnose.
How is CSF reabsorbed?
By arachnoid granulations in the superior saggital sinus. It is driven by hydrostatic pressure and is magically one-way (nothing flows back into the CSF)
What spinal level is iliac crests?
L4
What structures does the needle pass through to get into the subarachnoid space?
Skin and Subcu
Supraspinous ligament
Interspinous ligament
Iigamentum flavum (that’s the popping sound)
Posterior epidural space (there is a venous plexus here)
Dura
Subarachnoid space and nerve roots of the cauda equina
Where does fasiculus cuneatus start?
Above T6
What are the 3 main white matter groups in the spinal cord?
- Posterior column (decussates at medulla)
- Fasciculus gracilis (light touch, proprioception)
- Fasciculus cuneatus (above T6)
- Lateral column
- lateral corticospinal tract (motor- decussates at pyramids)
- rubrospinal tract
- spinocerebellar (sensory- proprioception)
- Anterior column
- spinothalamic (pain and temperature- decussates at spinal level )
- vestibulospinal
- reticulospinal
- anteriocorticospinal (motor)
SNS/PNS carried in lateral horn (therefore spinal cord will only have a lateral horn from T1-L2, S2-S4)
Extension vs. flexion posturing and where the site of the lesion is.
Extension (AKA: decerebrate): below red nucleus
Flexion (AKA: decorticate): (flex to coeur) rostral to red nucleus
Which cranial nerves are motor, which are sensory and which are mixed?
3-5-4
Sensory:
- I: olfactory
- II: optic
- VII: vestibulocochlear
Motor (the eyes, the shrug, the tongue)
- III: Oculomotor (visceral and somatic)
- IV: Trochlear
- VI: abducens
- XI: accesory
- XII: hypoglossal
Mixed
- V: trigeminal (somatic only)
- VII: facial (visceral and somatic)
- IX: glossopharyngeal (visceral and somatic)
- X: vagus (visceral and somatic)
PNS nerves are the same as the mixed group if you swap V for III
What do the nucleus ambiguus and solitarius do?
Solitarius is sensory for 9 and 10
aMbiguus is motor for 9 and 10
Where in the spinal cord are the ascending (PCML, spinothalamic, spinocerebellar) and descending (corticospinal) tracts located?
UMN vs. LMN symptoms
UMN:
- spasticity
- increased tone
- Increased reflexes (incl. Babinski)
- increased muscle mass
LMN:
- fasciculations
- decreased tone
- decreased reflexes
- decreased muscle mass
(in upper, things increase. In lower, things decrease)
VIral insults usuallly have _________ borders whereas vascular insults have ______indistinct
distinct (viruses usually have tropism) vs. indistinct
What is the blood supply of the spinal cord?
ASA and PSA get their blood supply from radicular arteries…below T8 ish there is only the artery of adamkiewicz supplying the ASA so it is vulnerable to ischemia
Bladder control…
- what do SNS and PNS each do?
- what is the PMC and what is it’s role?
- what is Onuf’s nucleus and what is it’s role?
- How are pain, temp and bladder fullness sensed?
SNS (T12-L2): promotes urine retention. B3 relaxes detrusor, alpha contracts internal sphincter.
PNS: promotes bladder emptying. S2,3,4 causes contraction of detrusor, inhibits SNS mediated contraction of internal sphincter
PMC: promotes micturition. Is inhibited by cortical input
Onuf nucleus: nucleus of motor neurons in S2,3,4 that tonically contracts the external sphincter
Fullness: PNS S2,3,4
Pain and Temp: PNS and SNS then goes through spinothalmic
Differentiate overflow incontinence, spasctic bladder
Overflow incontinenence: usually bladder outlet obstruction. Bladder becomes distended and irritable
Spastic bladder: neurogenic…affects nerves innervating
Reflex bladder: reflex arc from bladder to S2,3,4 then urination
What tracts are found in the anterior limb, genu and posterior limb of the internal capsule?
Anterior: corticopontine, thalamocortical fibres (DM and ant. fibers)
Genu: corticobulbar (comes from PMC just like corticospinal fibers…)
Posterior: corticopontine, thalamocortical fibres (VP, VM, VA), corticospinal
Where are the tectum, the tegmentum and the base of the brain?
They are like sandwich layers: the base is the anterior surface, then the tegmentum, then the ventricles (3rd–> cerebral aqueduct–> 4th) then the tectum (only found at level of midbrain)
Where are the pyramids, the olives, fasculus cuneatus and gracilis?
Pyramids and olives on are the anterior medulla, FG and FC are on the posterior surface. Basically there are two bumps on the front and two bumps on the back
What is the MLF? What does it connect?
Medial longitudinal fasciculus is split into ascending and descending
- ascending: connects III and VI (bypasses IV ?), and the vestibular nuclei to higher centres and III/IV/VI
- descending (AKA vestibulospinal): from vestibular nuclei to spinal cord so we can use our muscles to maintain balance and move our head and neck
Pretty much goes from oculomotor nucleus in midbrain all the way down the open medulla and tracks near the ventricle/cerebral aqueduct
What is the difference between SVE and GSE? GVA and SVA?
General= neurons that can be found elsewhere in the body
Special= neurons that are only found in cranial nerves (=vision, hearing, taste, smell…taste and smell are considered “visceral” because they are part of digestion/gut stuff)
Somatic= includes meninges, skin sensation, pharynx/larynx (??), intrinsic muscles of tongue
Visceral= pharyngeal muscles, intrinsic laryngeal muscles (skeletal?), smooth muscle of pharynx/larynx
SSA: hearing and balance and vision
GSA: general sensation
SVA: taste and smell
GVA: afferents from viscera in the core
(sulcus limitans)
GVE: preganglionic autonomics to the core and glands of the head and neck
SVE: muscles from branchial arches
GSE: muscles from somites (incl. extraocular muscles)
(midline)
Where are the oculomotor, trochlear and abducens nuclei?
Oculomotor
- main oculomotor: in anterior PAG
- edinger-westphal: just posterior to motor nucleus in PAG
- surrounded by MLF
Trochlear
- in anterior part of PAG, but exits brainstem posteriorly
Abducens
- posterior pons
Why does CN III compression result first in pupil dilation instead of loss of extraocular movements?
Because the PNS fibers are mor exterior in CN III
What muscles does CNIII innervate?
GSE: superior rectus, medial rectus,inferior rectus, inferior oblique, levator palpebrae superioris
GVE: constrictor pupillae (change pupil diameter), ciliary muscles (change lens shape)
What does the superior oblique muscle do?
Intorts, depresses the adducted eye (the bottom half of the H tests for SO function)
What are the alar and basal plates, how are the different modalities arranged in the brainstem?
Alar plate: gives rise to sensory (GVA, SVA, GSA, SSA)
Basal plate: gives rise to motor (GSE, SVE, GVE)
What is the point of the vestibulo-ocular reflex?
To train the eye on a target while the head is moving side to side.
What is the path for reflexive and volition saccades?
Image in left field –> left LGN–>primary visual cortex–> association fields + FEF–> either left superior colliculus (for reflexive) or straight to right PPRF (volitional).
Then wiring is the same for horizontal eye movement
What would damage to the MLF do?
Can’t turn the eye inward (contract medial rectus)
What is the COWS mnemonic for?
Cold Opposite, Warm Same
Describes the result of caloric testing- the way the fast movement of the saccade would go. If the testing is normal (COWS) that part of the brainstem is intact
Where are the PPRF, the vertical gaze and the vergence centres located?
PPRF: pons
Vertical: pretectal area
Vergence centre: rostral midbrain, near CN III nucleus
Does a cranial nerve have to have only one nucleus associated with it?
No, it usually has one nucleus per modality it carries
Which cranial nerves do taste?
Anterior 2/3 tongue: CN VII
Posterior 1/3 tongue: CN IX
Larynx/posterior pharynx: CN X
All taste fibers project to the nucleus solitarius –> VPM–> insula
What modalities are carried by IX?
IX (glossopharygeal) has 5:
- GSA: sensation from posterior 1/3 tongue, tonsils, skin of external ear, internal surface of tympanic membrane, pharynx
- GVA: chemo/baro receptors from carotid bodies, gag sensation from pharynx (afferent limb of gag reflex)
- SVA: taste from posterior 1/3 tongue
- SVE: stylopharyngeus muscle
- GVE (PNS): stimulation of parotid gland (via lesser petrosal–> auriculotemporal)
What modalities are carried by the vagus?
4 modalities
GSA: posterior meninges, concha of ear, skin on back of ear, pharynx and larynx
GVA: larynx, trachea, thoracic and abdo viscera, Ao arch chemo/baro receptors
SVE: pharyngeal constrictors (sup, middle, inf), levator palatini, salpingopharyngeus, palatopharyngeus, palatoglossus, cricothyroid, intrinsic muscles of larynx
GVE: smooth muscle and glands of pharynx, larynx, thoracic and abdo viscera, cardiac muscle (supplies PNS to viscera up to splenic flexure)
Where is the nucleus solitarius and what CNs are associated with it?
GVA for:
- VII
- IX: chemo/baro receptors for carotid bodies, gag sensation from pharynx
- X: larynx, trachea, esophagus, thoracic and abdo viscera, chemo/baro in Ao bodies and arch
SVA for
- IX: taste from posterior 1/3 tongue
It is found in …>?
Where is the nucleus ambiguus and what CNs is it associated with?
Nucleus ambiguus:
- GVE for
- X: cardiac muscle
- SVE for
- IX: stylopharyngeus muscle
- X: pharyngeal muscles..
Where does IX emerge from brainstem and where does it go through the skull?
Where does X emerge from the brainstem and where does it go through the skull?
- IX and X emerges from rostral medulla, posterior to olive. X is superior to IX
- IX and X travel intracranially and exit through the jugular foramen (IX, X, XI) except for the lesser petrosal nerve (PNS to parotid gland) which travels intracranially and exits through the foramen ovale with V3
What nuclei are associated with IX?
What nuclei are associated with the vagus?
Each modality has it’s own nucleus
What modalities are carried by XI? Where does exit the brainstem and the skull?
GSE (LMN’s) to trapezius and SCM.
Input (UMN) is from corticobulbar tract and goes to cell bodies in upper cervical cord that enter the skull through foramen magnum and exit in the jugular formaen (IX, X, XI)
Corticobulbar (UMN ) is contralateral to trapezius and and ipsilateral to SCM
What modalities are associated with XII, where does it exit the spinal cord and where does it exit the skull?
XII (hypoglossal) innervates extrinsic muscles of the tongue (GSE (LMNs)). UMN input is from corticobulbar tract and is contralateral and LMN to tongue muscles is bilateral.
Exits medulla between olives and pyramids
Exits skull through hypoglossal canal
What CNs do sensory to the pharynx?
Nasopharynx: VII
Oropharynx: IX
Laryngopharynx: X
What nuclei are associated with XII?
What is the path for pupillary constriction?
What is the path for the pupillodilator reflex?
What is the path for the corneal reflex?
Afferent: V1–> trigeminal sensory nucleus
Efferent: facial nucleus–> VII–> orbicularis oculi
What are the pathways involved in the accomodation reflex? Can it be tested on an unconscious patient?
Tested on conscious patients only
What fibers do you use to feel something in the pharynx? What fibers do you use to gag?
Sensation: GSA –> trigeminal nucleus
Gag: GVA of IX –> tractus solitarius –> nucleus solitarius
What are the pathways in the gag reflex?
Afferent: Sensed by GVA of IX –> tractus solitarius–> nucleus solitarius
Efferent: nucleus ambiguus–> SVE of vagus –> pharyngeal muscles
What is the difference between decorticate and decerebrate posturing?
In both cases all descending cortical systems are interupted (corticospinal, corticorubral, corticoreticular).
In decorticate rubrospinal and reticulospinal tracts intact
In decerebrate only reticulospinal intact- extensor posture from excessive excitation.
Decorticate= flexor. Lesion is rostral to red nucleus
Decerebrate= extensor
What are the three cranial fossae?
Types of brain herniation and the symptoms of each.
- Subfalcine (under the falx cerebri)(AKA: cingulate): compresses the ACA against the falx in the side that is pushing under. The ACA supplies most of the medial cortex (the lower part of the homunculus) so you get lower limb weakness on the contralateral side.
- Transtentorial (uncal): e.g. temporal mass, pushes uncus and compresses CN III (mydriasis- N.B. the PNS fibers are on outside and get compressed before oculomotor fibers do) , PCA, cerebral peduncle (paralysis/pareisis on contrlateral side)
- Foramen magnum herniation: cerebral tonsils compress the medulla. Death ensues.
What muscles does each end of the H-test test?
What is the reticular formation? What are the 3 zones/components?
A network of interconnected neurons found in the brainstem and spinal cord that is basically the intergrator of the CNS.
It cannot be seen on micrographs but can be divided into 3 functional components:
- Lateral zone: processes sensory (afferent) information
- Medial zone: processes motor (efferent) information (**fits the medial- motor rule)
- Neurotransmitter systems
What is the ARAS?
Ascending reticular activating system: everything from the reticular formation that ascends to the brain. Plays a role in regulating consciousness
What the main NT systems of the brainstem and where does each originate from?
Dopaminergic
- VTA (ventral tegmental area)
- Substatia nigra
5-HT
- Raphe nucleus (midline the length of spinal cord)
Adrenergic
- locus ceruleus (pons, near 4th ventricle)
Cholinergic
- tegmentum of pons
Histamine
- tegmentum of midbrain
A: forceps minor of corpus callosum
B: forceps major of corpus callosum
A: insula
B: 3rd ventricle
A: thalamus
B: pons
C: 4th ventricle
What are the two kinds of pain fibers and where do they synapse in the posterior?
- A-delta: sharp, fast pain: synapse in lamina I (NS), II, V (WDR- wide dynamic range receive painful and nonpainful stimuli)
- C fibers (unmyelinated): synapse in lamina I, II (NS)
What are the components of the anterolateral system and where do they synapse?
All: have cell body in DRG, enter cord through posterior horn, go up or down a few levels, synapse in the posterior horn, decussate through the anterior white commisure and ascend
Spinoreticular tract: gets off in the pons and goes to Raphe nucleus, locus ceruleus
Spinomesencephalic: gets off at the PAG in the midbrain. Also projects to sup. colliculus to divert eyes towards pain
Spinothalamic: synapses in VPL –> primary SS cortex; DM–> limbic system
Which lamina in the posterior horn is the substantia gelatinosa? How many lamina are in the posterior horn? Which ones contain the NS neurons and WDR?
Posterior horn has 6 lamina, II is the substantia gelatinosa. I and II have NS and VI has WDR…. maybe more?
Describe modulation of pain at the level of the spinal cord
1) Gate control theory: A-beta sensory fibers and A-delta pain fibers both synapse on an inhibitory interneuron. When you rub a sore spot the extra A-beta stimulation turns the inhibitory interneuron on and it inhibits ascension of the A-delta signal.
2) Descending from PAG
3) Interneurons in SG
What kind of pain modulation comes from the brainstem
Descending inhibition via interneurons using a variety of neurotransmitters including glu, NE. 5-HT, dopa. From PAG, LC, Raphe…
Would also modulate pain input via the spinoreticular and spinomesencephalic tracts
Describe the central modulation of pain
The endogenous opiod system. Receptors are found all along the pain pathways. Enkephalins, endorphins, dynorphins
What part of the brain is involved in localizing pain? The affective component of pain?
There is no “pain centre” but rather a “cortical pain matrix” that is divided into two systems
Localizing pain: “lateral” system, from A-delta fibers –> VPM, VPL–> primary and secondary somatosensory cortices
Affective: “medial” system, from C-fibres –> DM–> anterior cingulate cortex, amygdala, hippocampus, hypothalamus.
The cortical pain matrix is also active when determining saliency of non-painful stimuli
What modalities are associated with CN V and where does it exit the brainstem and the skull?
V exits the brainstem at the mid-pons, the ganglia sits on the floor of the middle cranial fossa, then:
- V1: superior orbital fissure
- V2: foramen rotundum
- V3: foramen ovale
Contains:
- GSA: general sensory to face
- pain and temp go to spinal trigeminal tract and nucleus
- light touch and vibration go to chief nucleus of V
- proprioception from chewing goes to mesencephalic nucleus
- SVE: muscles of mastication come from motor nucleus of V
Which nuclei and tracts are associated with V?
- chief sensory nucleus (light touch, vibration, proprioception)
- trigeminal lemniscus (projects to VPM)
- spinal nucleus and tract (pain and temp) ( extends from pons to medulla)
- trigeminalthalamic (projects to VPM)
- mesencephalic (unconscious proprioception) (in midbrain)
- no real tracts associated with it
- motor nucleus of V (muscles of mastication)
- corticobulbar tract (bilateral input)
What part of the face does each branch of V do?
V1: upper face and orbit
V2: midface to upper teeth
V3: lower face, lower teeth
What are the modalities carried by VII? Which nucleus does each project to?
Each projects to its own nucleus…
GSA: skin behind the ear–> spinal trigeminal nucleus
SVA: taste from anterior 2/3 of tongue–> nucleus solitarius
GVE: glands of the head (e.g. lacrimal, not parotid (this is glossopharyngeal)–> superior salivatory nucleus
SVE: muscles of facial expression–> facial motor nucleus
What is the motor innervation for the upper and lower parts of the face?
Upper: bilateral input from the cingulate motor area via the corticobulbar tract -> facial nucleus
Lower: contralateral input from the PMC via the corticobulbar tract –> facial nucleus
What is the clinical result of an UMN and LMN to the muscles of facial expression?
UMN: contralateral lower face weakness (bilateral input to upper face from cingulate motor area still intact)
LMN: ipsilateral weakness of the entire side of the face.
***look this up elsewhere….the internet makes no mention of the cingulate motor cortex
What vessels do the vertebral arteries come off of?
The right and left subclavian
What perfuses the numbered areas?
1) posterior spinal arteries
2) anterior spinal artery
What perfuses the numbered areas?
1) posterior spinal artery
2) vertebral artery
3) anterior spinal artery
1) posterior spinal artery
2) PICA
3) Vertebral artery
4) anterior spinal artery
What perfuses the numbered areas?
1) Superior cerebellar
2) Basilar
What perfuses the numbered areas?
1) superior cerebellar artery (overlaps with short branches of the PCA)
(bottom part is PICA)
What are the medial, lateral, inferior and anterior boundaries of the hypothalamus?
Medial: 3rd ventricle
Lateral: Internal capsule
Anterior: anterior commisure, optic chiasm, lamina terminalis (whatever this is….)
Inferior: mamillary bodies (really they are part of the HT so they form the inferior border)
Divisions of the hypothalamus
Lateral and medial: divided by the columns of the fornix (outflow of hippocampus) as they go to the mamillary bodies
- Has two groups of nuclei
- lateral: contains scattered bundles.
- medial: contains the important nuclei listed below
Anterior and posterior: functional division
- Has three groups of nuclei
- Anterior: near optic chiasm (4 nuclei)
- Middle: tuber cinereum (3 nuclei)
- Posterior (2 nuclei)
How is the hypothalamus linked to the pituitary gland (what are the important anatomic structures)?
Via. infundibulum (begins at tuber cinereum, which is a bulge between the optic chiasm and the mamillary bodies (mamillary bodies are part of hypothalamus…)
What are the functions of the lateral and medial hypothalamic nuclei?
Lateral: eating, arousal
Medial: satiety, ADH, GH
What do the anterior and posterior hypothalamus control?
Ant: PNS, decrease body temp, sleep, eat
Post: SNS, increase body temp, arousal, wakefulness
1: anterior commisure
2: optic tract
3: 3rd ventricle
4: hypothalamus
1: Columns of the fornix (hippocampal outflow)
2: optic chiasm
Blue: thalamus
Gray: hypothalamic sulcus
Orange: columns of the fornix (corpus callosum)
Red: mamillary bodies
Purple: anterior commisure
Green: hypothalamus
Where are the mamillary bodies, the orgin of the infundibulum and the tuber cinereum?
Green: mamillary bodies
Gray: origin of infundibulum
Purple (tuber cinereum)
A nice image with overall anatomy of the connection between the HT and the pituitary. Note the median eminence, the hypohyseal artery…
Just pretty
What are the parts of the limbic “lobe”?
“lobe” because it’s not a true lobe..it’s a ring of cortex
Hippocampus (yellow) and amygdala (red)
What are the functions of the hippocampus and the amygdala?
Hippocampus: learning, memory formation and retrieval, adult neurogenesis
Amygdala: emotional learning and memory, fear, reward, emotional saliency filter, enhances hippocampal memory
What are different types of memory?
The hippocampi are located inferior to the lateral ventricles
Where is the amygdala located in coronal section
It is anterior to the hippocampus (the lateral ventricles are not visible) and superior to the uncus
What is the “Papez circuit”?
The underlying circuitry for the limbic system.
Another view of the Papez circuit
The extended Papez circuit
What is the blood supply to the hypothalamus?
Anterior: ACA, anterior communicating
Posterior: PCA, posterior communicating
What is the blood supply to the hippocampus and amygdala?
PCA, anterior choroidal
What is the blood supply to the limbic lobe?
Cingulate cortex: ACA
entorhinal cortex (including uncus): PCA
Trace the path of smell
- Bipolar neurons through cribiform plate, synapse in the olfactory bulb
- olfactory bulb –> olfactory tracts–> medial and lateral olfactory striae
What is the difference in gaze between a seizure and an ischemic event?
With a seizure affecting the right FEFs, they become hyperactive and initiate gaze to the left.
With an ischemic event the right FEFs would become hypoactive and gaze would deviate to the right
(gaze is contralateral…)
Primary motor area is the dark green band
Premotor association area is the light green. The lower arrow is the premotor association area, the upper arrow is the supplemental motor area
Light brown: primary visual cortex
Dark brown:Visual association area
Arrow is pointing to calcarine sulcus
Circle: frontal eye fields
Dark purple: motor hand area
Light pink: primary auditory area
Dark pink: auditory association area
Trace the path of sound to the brain
Cochlea–> VIII–> medial geniculate nucleus of thalamus (bilateral)–> primary auditory area and association areas in temporal lobe
Located in the lateral fissure.
White: insular cortex (involved in consciousness, self-awareness, emotion etc…)
Purple: primary gustatory area
Where are the language centres of the brain?
Broca’s: allows for speech production
Wernicke’s: found in temporal lobe, spanning the auditory association area. allows for language comprehension
Frontal association area: AKA prefrontal cortex. involved in executive funciton
Temporal association area: links visual stimulus and meaning
Parietal association area: orienting attention in time and space
What is the difference between unimodal and heteromodal association areas? Where is each usually located?
Unimodal: process a single sensory or motor modality, typically found adjacent to primary motor or sensory areas (visual, auditory, somatosensory, supplemental motor, premotor, language (Broca/Wernicke))
Heteromodal: process more than one sensory or motor modality (frontal, parietal and temporal association areas)
(grey=heteromodal, yellow=unimodal, pink=primary sensory or motor areas)
What deficit would be seen with a lesion to the primary somatosensory area vs. somatosensory association areas?
Primary somatosensory: poor localization of stimuli/decreased awareness of stimuli
Somatosensory association: tactile agnosia, astereognosis b/c can’t integrate sensory information
What deficits would be seen with lesions to the primary motor area vs. premotor area vs. supplemental motor area?
Primary motor: UMN (hyperreflexia, hypertonia, spasticity, weakness)
Premotor: deficits in learned, skilled motor activities (apraxia)
Supplemental: deficits in posture, limb planning, coordination
What deficit would be seen with a lesion to the primary visual area vs. the visual association area?
Primary visual area: visual deficits (depends on where lesion is- visual area is organized retinotopically)
Visual association area: deficits in ability to recognize objects in the opposite visual field (visual agnosia) and in visual pursuit
Deficits in motor hand area?
Motor hand area is part of the primary motor area. Would see problems with position sense and fine movements contralaterally. Sensory and motor intact.
Deficits with frontal eye field lesion?
Frontal eye fields are part of supplemental motor area. Would have difficulty intiating eye movements
What deficits would be seen with lesions in the primary auditory area and the auditory association area?
Primary auditory area: decreased perception of sound in both ears but esp. CL ear
Auditory association area: decreased ability to interpret what is heard (acoustic verbal agnosia)
What is the difference between Wernicke’s aphasia and Broca’s aphasia? What are the dominant and non-dominant language functions?
Broca: “expressive” (AKA- motor aphasia)- inability to form speech (halting, sparse speech)
Wernicke’s: “receptive” (AKA- sensory aphasia)- inability to understand speech (gibberish, superfluous speech)
Dominant hemisphere: produce words and understand what is said
Non-dominant: melody, accent, tone
What is conduction aphasia?
have fluent speech, preserved comprehension but repetition is impaired (lesion to arcuate fasciculus).
What deficits would be seen in lesions to frontal vs. parietal vs. temporal association areas?
Frontal: personality changes and excutive functioning
Parietal: tactile agnosia, contralateral neglect with a lesion to the non-dominant hemisphere
Temporal: inability to recognize faces or people (agnosia) +/- prosopagnosia (face blindness)
What are the anatomical parts of corpus callosum and what does each part do?
Body: connects parietal lobes and posterior part of frontal lobes
Splenium (posterior):occipital lobes and posterior temporal lobes
Genu: frontal lobes
Rostrum ?
What are the commisural, association and projection fibre tracts of the brain (list)?
Commisural (2 hemispheres)
- Corpus callosum
- Anterior commisure
- Posterior commisure
Association (within same hemisphere):
- Short association fibres (arcuate fibres) connect adjacent gyri
- Long association fibres
- Superior longitudinal fasciculus (AKA arcuate fasciculus) connects frontal, parietal and temporal
- Inferior occipitofrontal fasciculus (contains uncinate fasciculus)
- Cingulum
Projection (cortex<–>thalamus)
- Corona radiata–>internal capsule
Where are the superior longitudinal, inferior occipitofrontal and uncinate fasiculi?
Where are forceps minor and major of the corpus callosum?
What is the blood supply to the internal capsule?
Anterior: lenticulostriate (branches of MCA and ACA) and ACA
Genu: anteriorchoroidal (from MCA)
Posterior:
Which thalamic nuclei do motor, sensory and limbic information go through?
Motor
- VA and VL
Sensory
- somatosensory: VPL (body), VPM (head)
- vision: LGN
- hearing: MGN
Limbic
- anterior nuclei
What artery supplies this?
PCA
Which fissures do the MCA and ACA travel in?
MCA: lateral
PCA: medial
What supplies 3,4,5
3: lenticulostriate arteries
4: deep branches of PCA
5: anterior choroidal
What supplies 3 and 4?
3: lenticulostriate
4: deep branches of PCA
Trace the path of the visual stimuli to the primary visual area/
Points to remember:
- lower visual field projects on the upper retina, which projects to the upper half of visual cortex (above the calcarine fissure).
- The lower half of retina has to loop around the inferior horn of the lateral ventricle (called Meyer’s loop) and can be affected by a temporal lobe defect.
- Temporal visual fields/nasal retina decussate in the optic chiasm.
Path:
retina–>optic nerve–>optic tract–> LGN of thalamus (+ sup. colliculus)–> optic radiations–> primary visual cortex–> ventral (what) and dorsal streams
What space does the circle of willis lie within?
The subarachnoid space
What structures are part of the basal ganglia? What are the striatum, the lenticular nucleus and the nucleus accumbens?
Caudate
Globus pallidus (internal and external)
Putamen
substantia nigra (found more posteriorly)
subthalamic nucleus (found more posteriorly)
- caudate + putamen= striatum (they are of common embryologic origin) (ventral part AKA nucleus accumbens)*
- putamen +globus pallidus= lenticular nucleus*
What is the ansa lenticularis? What NT does it use? What is the gist of the release inhibition model?
Outflow from globus pallidus to the thalamus- uses GABA (thalamus is tonically inhibited)
Release-Inhibition model: the thalamus is tonically inhibited. The direct pathway releases that inhibition (–>more cortical output, targeted movements), the indirect pathway reinforces that inhibition (–>less cortical output, suppresses competing movement). The net effect of the two pathways is to streamline cortical movement
What are the corticostriatal pathway, nigrostriatal pathway, subthalamic fasciculus and the ansa lenticularis?
Corticostriatal: cortex –> caudate+putamen (striatum)
Nigrostriatal: substantia nigra –> caudate + putamen (striatum)
Subthalamic fasciculus: suthalamic nucleus <–> GPe and GPi
Ansa lenticularis: GPi–> thalamus
What is the blood supply of the subthalamic nucleus and substantia nigra?
Supply only by deep branches of PCA.
What are the three circuits between the basal ganglia and cortex?
Motor circuit: input to putamen
Associative circuit: frontal/temporal/parietal associative areas input to nucleus accumbens
Limbic circuit: hippocampus/amygdala/frontal association input to nucleus accumbens
**all input to the striatum, specifically to the areas listed above, then move through direct/indirect pathways, activate different parts of the thalamus, and relay back to the cortex or down.
Ballism and Huntington’s are lesions to what? Parkinson’s is a lesion to what?
- Ballism: subthalamic nucleus*
- Huntington’s: striatum (striatal neurons are associated with both the direct and indirect pathways BUT HD affects indirect first)*
- Both result in hyperkinetic movement disorders*
Parkinson’s is a lesion to the substantia nigra. Is a hypokinetic movement disorder
What do “pyramidal” and “extrapyramidal” refer to?
Pyramidal: UMN signs (i.e. involving corticospinal tract). Spasticity, weakness, hyperreflexia, hypertonicity, Babinski
Extrapyramidal: involving the basal ganglia
Where are the vermis, floccus and nodule on the cerebellum?
Nodule is in middle, floccus lateral
What are the anatomical vs. functional lobes of the cerebellum?
Anatomical:
- posterior
- anterior
- flocconodular
Functional:
- cerebrocerebellum (most of posterior lobe)
- spinocerebellum (flocculonodular)
- vestibulocerebellum (vermis, paravermis, anterior lobe)
What are the three functional loops of the cerebellum and what does each do?
Vestibulocerebellar: balance
Spinocerebellar: trunk and limb movements
Cerebrocerebellar: hand-eye coordination, streamlines cortical output
Incoming and outgoing connections in the vestibulocerebellar loop
Input from:
- vestibular nuclei, bilateral
Outgoing (via fastigial nucleus)
- vestibular nuclei
- reticular formation
- both of the above project to spinal cord to affect postural muscles
What general types of information travel through the superior, middle and inferior cerebellar peduncles
Superior: more complex…memory, motor, language
Middle: carries afferents only
Inferior: more archaic…balance
What is the input and output to the spinocerebellar loop?
Input:
- spinal cord (e.g. proprioception)
Output (via E,G,F ….AKA “deep nuclei”)
- rubrospinal (red nucleus)
- reticulospinal (reticular formation)
- vestibulospinal (vestibular nuclei)
- thalamus
N.B: to get to limbs, info has to go back to the cortex then down to limbs vs. vestibulospinal which appears to be able to go straight to spinal cord to influence postural muscles
What is the input and output of the cerebrocerebellar tract?
Input:
- CL cortex via pontine nuclei
Output:
- CL red nucleus via dentate nucleus thru dentatorubrothalamic tract)
- Has to go red nucleus–> cortex–> spinal cord to influence LMN
What is the blood supply of the cerebellum?
Blue is PICA….
Compare the function of the basal ganglia and the cerebellum
Basal ganglia:
- permits target orientation and suppresses competing movement
Cerebellum
- coordinates and predicts movement
- skilled movements
Conseqeuences of lesions to posterior lobe of cerebellum (cerebrocerebellum)?
vs.
Consequences of midline cerebellar lesion
Posterior lobe:
- dysmetria (hand-eye coordination)
- dysdiadochokinesia (coordination of agonist-antagonist movt)
- linguistic incoordination
Midline (vermis, paravermis, nodule)
- truncal instability
- truncal ataxia
- nystagmus
Pretty pic of thalamus
