Glossary of Neuroanatomy Lab

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Where is the primary motor cortex
Precentral gyrus of frontal lobe
Where is the speech area?
Broca's area
L inferior frontal gyrus
Where is the primary somatosensory cortex?
Postcentral gyrus of parietal lobe
Where is the primary auditory cortex?
Transverse gyri of Heschl, in the lower bank iof the lateral fissure of the temporal lobe
Where is the primary olfactoryy cortex?
Medial-anterior temporal lobe (including uncus and anterior part of parahippocampal gyrus)
Where is the lanuage area?
Wernicke's area,
left superior temporal gyrus
Where is the primary visual cortex?
Banks of calcarine fissure
Where is the calcarine fissure?
occipital lobe
What does the insula do?
deals with visceral and autonomic function, including taste and pain
Where is coordination and motor learning located?
What do you call the overhanging piecees of cortex over the insula?
What does cingulate gyrus do?
Participates in emotion and motivation

Implicated in addivtive behaviors, emotional response to pain
What is the foramen of monro?
Opening thru which CSF passes from paired lateral ventricles into the third ventricle

Bounded by the thalamus and hypothalamus on each hemisphere
What does the thalamus do?
All sensory imput BUT smell is processed there, before being sent to cortex. It is also tightly linked to the cerebellum and other structures for regulation of motor control
What is the anterior commissure?
Bundle of axons interconnecting regions of the temporal lobe
What does the hypothalamus do?
regulates the autonomic nervous system.

Governs reproductive, homeostatic, and circadian functions.

Important in motivational responses
What is the optic chiasm?
Optic nerves from each eye meet here. Some axons cross.

Pituitary gland lies just below, infundibulum lies just behind
What is the parahippocampal gyrus
Cortical region that overlies the hippocampus. Cortex appears more primitive here.
What is the uncus
Medial protrusionof the parahippocampal gyrus.

Overlies a part of the AMYGDALA, a subcortical nucleus.

Because of its position, te uncus is likely to HERNIATE when intracranial pressure increases, pressing on the midbrain and inducing coma
What is the midbrain?
The TEGMENTUM is the floor of the midbrain. Above this is the cerebral aqueduct, Above that is the Midbrain TECTUM (roof)
What is the pons?
Bunges out because of the many nuclei that relay cortical information to the cerebellum
Describe 4th ventricle
CSF flows in from 3rd ventricle thru cerebral aqueduct. It exits into the subarachnoid space through FORAMEN OF MAGENDIE and 2 lateral openings (FORAMENA OF LUSCHKA). Continuous wit cerebral aqueduct of the spinal cord
Describe the midbrain tectum.
Composed of 2 sets of bumbps called the superior and inferior colliculi.
What are the superior colliculi involved in?
What are the inferior colluculi involved in?
What does the pineal gland do?
It overhangs the midbrain tectum.

Not nerual tissue

Thought to play a role in circadian rhythmicity.

Tumors can press on regions caudal that are involved in eye movements, especially control of upward ae and pupillary responses
What is the lingula?
Region of the occuputal lobe below the calcarine sulcus.

CONTRALATERAL UPPER visual field is represented here.
What is at the calcarine sulcus?
The banks of it are the primary visusal cortex.

The fovea is represented most caudally, near the occipital pole.
What is the cuneus? What happens there/
It is a region of the occipital lobe ABOVE the calcarine sulcus.

The CONTRALATERAL LOWER visual field is represented here.
What separates the occipital and parietal lobes?
The parieto-occipital sulcus
What is the corpus callosum?
Massive system of axons that interconnect homologous regions of the 2 hemispheres.
Name the parts of the corpus callosum
Anterior part: rostrum
Middle part: Body
Caudal part: splenium
What is the fornix?
System of axons that runs from the hippocampus forward and medially, then BACKWARD to the mamillary bodies.
Where are the mammillary bodies?
The most caudal part of the hypothalamus.
Where is the paracentral lobule? What is represented there?
Medial surface of the brain: formed by the pre and postcentral gyri.

The LEGS are represented in the paracentral lobule.
What is the septum pellucidum?
Thin membrane formed from CT that forms the medial walls of the lateral ventricles.

Attaches to the corpus callosum and to the fornix.
What are the cerebral peduncles
Ventral portion of the midbrain.

Contain fiber tracts running to and from the cerebrum as well as important nuclear groups.
What does trigem nerve do? Where is it?
Sensory innervation of face, mouth, cornea.

Motor innervation to muscles of mastication.
What causes the pyramid in the medulla?
Formed by a large tract called the corticospinal tract that runs from motor cotex to spinal cord.
What causes the "olive"?
Medullary bulge caused by the inferior olivary nucleus, a prominent relay nucleus for fibers going to the cerebellum.
Where id trigem?
lateral to pons.
What does CN III do?

Motor innervation to all extraoculars except LR (6) and SO (4).

Also carries parasympathetic innervation of pupil. (Symp as well??)
What does CN 12 do?

Motor control of tongue
What does CN X do?

Parasympathetic innervation of gut
Sensation from pharynx
Muscles of vocal cords, swallowing
What does CN VIII do?

Hearing and balance
What does CN VII do?
Facial nerve.

Motor innervation of muscles of facial experssion

Taste from anterior 2/3 of tongue

Lacrimal and salivary gland innervation
What does CN VI do?
Abducens. Innervates LR.
What is the olive the source of?
climbing fibers to the cerebellar cortex
Where is the only site where sselective destruction of the corticospinal tracts can occur?
Medullary pyramid
How is cerebral cortex structured?
6 layers.

2 and 4 are specialized for reception of sensory info, and are well developend in teh primary sensory cortices.
Are there synaptic connections in dorsal root ganglia of spinal cord?
No. Ganglia are cell bodies of neurons that have one axon branch running to peripher and one branch running into spinal cord.
What is gray matter of spinal cord composed of?
Nuclei containing cell bodies of neurons. Nuclei run longitudinallyy over manny segments.
Which spinal cord segments are more round v . more oval?
Cervical: more oval

Thoracic: more round
How does ration of white to gray matter change over length of spinal cord?
More white relative to gray, the further ROSTRAL you are.
What is the substatia gelatinosa
Region of spinal cord gray matter containing small cells and very thin axons

Stains poorly
What does the ventral horn contain?
Motorneurons and interneurons related to motor activities.

Expands laterally in regions of cervical and lumbosacral enlargements
Where is the lateral horn present?
Which side of spinal cord is the fissure on?
What are the 2 major arterial domains n the brain and what are they supplied by?
1) anterior circulation: ICAs
2) posterior circulation: vertebral arteries
What is the PICA a branch of?
Vertebral artery
What is the AICA a branch of?
basilar artery
What supplies the lower medulla?
PICA and branches of the vertebral a.
What supplies the upper medulla?
What supplies the midbrain?
superior cerebellar A
What supplies the spinal cord?
1) descending branches of the Vertebral arteries
2) arteries that enter with the spinal roots (radicular)
What are radicular arteries?
Arteries that enter the spinal cord wiht the spinal roots
What supplies the dorsal side of lower pons?
Branches of the basilar artery, including AICA
What supplies lateral lower pons?
Short circumferential branches of the basilar artery
What supplies the ventral lower pons?
paramedian branches of the basilar artery
What supplies the dorso-lateral medulla?
PICA branches
What supplies the ventral and ventrolateral mid medulla (including olives)
vertebral artery branches
what ssupplies lateral part of lower medulla/stem?
vertebral artery branches
What supplies dorsal lower medulla/stem?
posterior spinal artery branches
what supplies ventral lower medulla/stem?
anterior spinal artery branches
Describe spinal cord blood flow
1) vertebral arteries ascend ventrolateral surface of medulla
2) each gives rise to paired posterior spinal arteries and a single anterior spinal artery
3) posterior spinals and anteriro spinals descend, medial to dorsal roots
4) they receive contributions from the radicual arteries
Describe general blood supply of a spinal cord section
1) dorsal colums and superficial dorsal horn are supplied by posterior spinal aterieS
2) everythign else=anterior spinal artery
Name the 3 major kinds of intracranial, extraparenchymal hemmorhage:
1) epidural
2) subdural
3) subarachnoid
What causes epidural hemorrhage
Usually head trauma, especially in temporal area where it can damage the middle meningeal artery
Where is a subdural hemorrhage?
between dura mater and the arachnoid mater
What causes subdural hemorrhage
When shearing forces rupture the bridging veins that cross this normally POTENTIAL space
Where is a subarachnoid hemorrhage?
between the arachnoid and pia mater
What causes subarachnoid hemorrhage
WHen one of many arteries or veins passing thru the space ruptures

(may cause bloody lumbar tap since CSF flowsn in this area
Where is CSF absorbed?
In the superior sagittal sinus thru the ARACHNOID VILLI
What artery supplies the paracentral lobule?
Anterior cerebral
What artery/s supplies the primary somatosensory and motor cortices?
Mainly middle cerebral, also anteror cerebral at top and in lateral fissure
What part of temoporal lobe can herniate through tentorial notch?
Medial temporal lobe
What supplies primary visual cortex?
Posterior cerebral
what goes through the tentorial notch?
What supplies primary auditory area?
middle cerebral a.
Fracture of what bone is most likely to cause epidural hemorrhage?
Temporal (thin, squamous part)
More specifically, what can be forced through the tentorial notch due increased pressure in supratentorial spcae?
What does tis pathway percept:

Retinal ganglion->LGN-->primary visual cortex
Visual form, color, movement
What does this pathway do?

retinal ganglion-->superior colliculs-->pulvinar-->cortical areas
visuospatial integration
how many synapses betwen retinal gangion cells and the calcarine sulcus?
Where is the synapse between retinal ganglion cells and visual cortex?
Lateral geniculate body
where are the cell bodies of neurons in left optic tract?
Right visual field:

Ganglia in R nasal retina and L temporal retina
What is the name for a defect in perceived visual space?
What result of a lesion of the optic nerve between retina and optic chiasm?
Blindness in ipsilateral eye
What result of a lesion through the center of the optic chiasm?
Bitemporal hemianopsia

(crossing fibers destroyed. thus, the nasal gangion cells from both eyes are cut. This results in loss of temporal fields of vision.)

AKA: heteronymous hemianopsia
What result of a lesion of the R tract after chiasm?
Loss of L nasal retinal cells and R temporal retinal cells. This cuts out the L field of vision.

Thus, CONTRALATERAL homonymous hemianopsia
Where do fibers representing the upper portion of a visual field track?
They sweep more laterally into the temporal lobe, and end up in the lower part of the visual cortex.

More vulnerable to destruction from blow to head.
Where do fibers representing lower part of visual field go?
After LGN, they go more medially and directly to the visual cortex, ending in the upper part.
What would a lesion of the temproal lobe most likeyl produce, vision-wise?
Lesion of Meyers loop, which are the more anteriorly and laterally sweeping fibers from LGN that end up in the lower visual cortex and represent the upper visual field. So they woudl cause a contralateral UPPER HOMONYMOUS QUADRANTOPSIA. Thus, lesion on R temporal lobe means you can't see upper L field of vision.
What result of complete destruction of primary visual corte x or optic radiations?
Contralateral homonymous hemianopsia, with MACULAR SPARING.
What result of damage to cuneus on one side?
Contralateral lower homonymous quadrantopsia
What result of damage to lingula on one side?
Contralateral upper homonymous quadrantopsia
What is macular degeneration?
Loss of visual elements in the macular region of the retina

Can be due to aging, disease, or hemorrhage
What is different anatomically about the macula/fovea?
Area of highes cone concentration--almost all cones
What does damage of right side of area MT cause?
left neglect syndromee
Where does the dorsal stream of info fromm the occipital lobe visual cortex go?
to area MT of the parietal lobe
what is area MT involved in?
spatial aspects of vision, such as the analysis of motion and positional relationships
Where doe sthe ventral stream of visiual info from the occipital lobe go?
area V4, AND
INferotemporal cotex
What does area V4 and the IT cortex do?
Involved in hi res form vision and object recognition
What does lesion of area V4 or the IT cortex result in?
What is prosopagnosia?
inability to recognize faces, caused by lesion of right area v4 or IT cortex
what is pupillary constriction mediated by?
Edinger-Westphal nucleus of the oculomotor complex
what is the Edinger Westphal nucleus?
The parasympathetic nucleus of CN III
Describe light reflex pathway
1) afferent imput travels through optic nerve, and a small number of nerves leave optic tract and synapse in the PRETECTAL NUCLEUS (near superior colliculus)

2) Note: some fibers go to pretectal nuclesu on EACH SIDE.

3) Synapse in pretectal area; then transmission to Edinger Westphal nucleus on BOTH SIDES

4) synappse in EW nucleus, and PS fibers trave back through CN III to the CILIARY GANGLION.

5) synapse; then SHORT CILIARY parasympathetics innervate the constrictor pupillae muscles.
What does Argyll-Robertson pupil look like?
pupillary response to LIGHT is lost, but pupillaryt respnse to accomodation is maintained. (LEsion site unknown)
What is Argyll-Robertson pupil associated with?
What is accomodation?
Pupillary constriction as gaze shifts to near object
What is saccadic movement?
Fast eye movement
What are the 2 cortical areas involved in eye movements?
Fronal eye fields
Parieto-occipito-temporal area
What are fronal eye fields important for?
Fast eye movvements (saccades) in shifting gaze
What is parieto-occipto-temporal area important in?
Smooth pursuit of visual objects
Which side movement does frontal eye field control?
Sacccadic movement on the contralateral side
Which side movement does parieto-occipto-temporal area control?
Ipsilateral smooth pursuit movement
Where do neurons in the two eye fields project directly to?
Brainstem nuclei AND
to ipsilateral superior colliculus
Where is the vertical gaze center?
In the midbrain tectum, just in front of superior colliculi
Where is the lateral gaze center?
near abducens nuclei
What is the real name for the lateral gaze center?
PPRF: Paramedian pontine reticular formation
What does activation of the PPRF on one side do?
Activates ipsilateral LR motorneurons and contralateral abducens motorneurons, moving eye laterallt toward that side.

Also, motorneurons ton andtagonistic muscles is inhibited.
What coordinates tha innhibition of antagonistic eye mosucles in movement?
MLF: the medial longitudinal fasciulus.
Where does PPRF get its input from?
Neurons w/bodies on contralateral side
Inability to move eye down and out suggests:
CN IV palsy (trochlear: sup oblique)
Ptosis, eye down and out
Complete CN III palsy

(Lat rec and Sup oblique take over)
What is parinaud's syndrome?
Inability to voluntarily direct their gaze upward, due to tumor of the pineal gland that presses on the vertical gaze center [that is analogous to the PPRF)
What would a lesion in the Edinger westphal complex/superior colliculi cause in the eye
Disrupt eye movements
ALSO: would cause ipsilateral pupillary dialtion
Connection with eye movement and vestibular system?
Labyringths of the vestibulart system provide input to the nucliei of III, IV, and VI via the MLF. These inputs from the vestibular system produce reflex conjugate eye movements in response to changes in the position of the body or to angular accelleration.
Where does CSF leave the 4th ventricle?
Foramina of Lucschka and Magendie
what is the caudate nucleus involved in?
Motor control
what is the internal capsule?
densely packed axons going to and from cortex
What axons are in the dorsal (spinal) roots?
central projections of sensory neurons whose cell bodies are in the dorsal root ganglia
What is in the anterior white commissure?
Axons of dorsal horn neurons that receive info from small diameter fibers. They cross to the opposite side of the cord here and then form the spinothalamic tract.
What makes up the dorsal columns?
Gracile and cuneate fasciculi
What do the dorsal colums do?
Convey info from large diameter sensory fibers
What is the zone/tract of lissauer?
Locate at the cap of the dorsal horn, it contains collaterals of small-diameter fibers that run longitudinally for 1-2 segments.
What does tract of Lissauer do?
It helps coordinate protective reflexes, such as the flexion reflex.
Summarize path of dorsal column/medial lemniscal system
1) large dorsal root fibers enter medial to small dorsal roots
2) enter dorsal column
3) ascend to low medulla
4) synapse in gracile or cuneate nucleus
5) immediately dessucate to opposite side via internal arcuates
5) ascend to VPL in thalamus
7) synapse again
8) ascend via posterior limb of internal capsule to the postcentral gyrus/primary somatosensory cortex
what does dorsal column/medial lemniscus system sense?
Fine touch
vibratory sensation
Where does DC-medial lemniscal system sense from?
legs, trunk, arms
What size fibers enter the dorsal column system?
What level is first synapse of dorsal column/medial lemniscal system?
caudal medulla
What level do you see the medial lemniscus form from the 2 nucleii?
what level does Medial lemniscus cut back medially?
midbrain, superior colliculii
Describe relative positions of 2 dorsal column/medial lemniscus primary nucleii?
Gracile: most medial and dorsal.
Cuneate: more lateral and ventral
What modalities are carried by the spinothalamic system?
Crude touch, pain, temperature
What size fibers convey pain and temp sensation from the periphery?
SMALL myelinated and unmyelinated fibers
Were do pain and temp sensation fibers enter the spinal cord?
via the LATERAL division of the dorsal roots
What happens to pain and temp sensation fibers as soon as they enter the spinal cord?
They run 1-2 segments up and down the cord in Lissauer's tracts, dropping off collaterals to the dorsal horn
what is the "reticular formation"?
A diffuse group of neurons extending from the medulla through the mesencephalon; thought to be involved in regulation of arousal, slwwp/wake/descending control of nociceptive info.

Spinothalamic neurons send collaterals here.
How does ST system defect present?
Not as a crude touch defecit, since people still have fine touch to compensate.

Shows up as a pain and temperature defecit
Where do spinothalamic axons terminate in the brain
1) mainly on the VPL of the thalamus, from where it goes to postcentral gyrus

2) Some go to more medial talamic nuclei, such as the intraolaminar nuclei, tahat project to anterior cingulate gyrus and to the anterior insula (thought to be involved in suffering response)
What is the general rule for where a pain/temp/crude touch lesion is based on dermatome sensitivity and why?
Lesion is usually 1-2 segments rostral to dermatome segment where impairment is first seen.

Due to fact that small neurons of the ST system entering the spinal cord send branches to 1-2 segments above and below entry point via lissauer's tracts.
Describe general path of ST neurons
1) small fibers enter dorsal horn lateral too medial lemniscus/dorsal colunmn system.
2) enter 1-2 sections above and below entry level via lissauer's tracts
3) Synapse immediately in dorsal horn
4) interneurons IMMEDIATELY dessucate via VENTRAL WHITE COMMISSURE, moving to contralateral anterolateral area
5) these secondary axons ascend, terminating mainly on VLP region of the thalamus
6) thalamic neurons project to postcentral gyrus
7) note tho: some secondary axons end on thalamic nuclei more medial to the VPL, then projecting to anterior cingulate gyrus and anterior insula (suffering)
Where else besides the VPL and more medial thalamic nuclei (intralaminar nuclei) do sponothalamic neurons send collaterals?
the reticular formation
What things might knock out the area of the spinal cord generally supplied by posterior spinal arteries?
1) posterior spinal artery defect
2) vitamin b12 defeciency (pernicious anemia)
3) Tabes dorsalis (tertiary syphillis)
What are the symptoms of deficiency of posterior spinal artery (or pernicious anemia or tabes dorsalis)
knocks out medial lemnisculs/doorsal column system. ST spared since entry is lateral to the area of defecit.

So: below lesion, you lose crude touch, vibratory, propriocetpion. Bilateraly, if entire posterior artery section is lost.
Describe tabes dorsalis
1) syndrome associated with tertiary syphillis
2) Degeneration of large diameter myelinated fibers and cell bodies
3) bilateral impairment in light touch, proprioception, vibratory sense for entire BODY AND FACE
4) pain and temperature sensation are UNAFFECTED
Name defects of an anterior spinal artery obstruction
1)Bilateral Loss of Pain and Temp sensation
2) spinal reflexes lost only AT the level of obstruction
What is syrengomyelia?
Where anterior white commissure running through grey matter H is interrupted by tumor at a level.
Defecits in syringomyelia?
Bilateral loss of pain, temp, crude touch, only at levels of lesion (in a band)
Whaere are the only sensory neuron cell bodies in the CNS?
The mesencephalic nucleus of the trigeminal
Describe track of somatosensory trigeminal fibers (maxillary, mandibular, opthalmic tracts)
1) Enter from periphery, through trigeminal ganglion.
2) Pain and temp fibers descend trough the medulla in the SPINAL TRACT of the trigem, terminating in the most caudal regions of the SPINAL NUCLEUS OF THE TRIGEM.
3) vibration, fine touch, etc fibers (large fibers) go to the PRIINCIPAL SENSORY NUCLEUS
4) from both places, they ascend to the VPM of the thalamus, synapsing there.
5) finally they go to face region of the postcentral gyrus.
Where generally is the descending/spinal nucleus of the trigeminal?
From mid medulla to bottom of pons
Name all 4 nuclei that trigem nerves come to?
1) descending/spinal nucleus of the trigem: small fibers carrying pain and temp
2) Principal sensory nucleus: carries large fibers dedecting vibration, fine touch, etc
3) Mesencephalic nucleus: contains sensory CELL BODIES that innervate sense organs for muscles of mastication
4) Motor nucleus: contains motoneurons that innervate muscles of mastication
Be sure to look up trigem system again
Why is it that an anterior spinal artery lesion would only knock out reflex loops at that level?
Because there are other blood supplies--the radiculars coming in wiht the spinal nerves keep the other secitions alive
What is descending nucleus almost continuous with at the level of the medulla/spinal cord junction?
substantia gelatinosa
How do you know if you are in caudal medulla?
You can still see gracile and cuneate nucleii
What is nearby the spiinothalamic tract in the caudal medulla, and what does it do?
Caudal extension of the median forebrain bundle.

Sympathetic control
What does vertebral artery supply in the caudal medulla?
1) descending/spinal nucleus and tract for V (trigem)
2) Spinothalamic tract runs pretty superficially and laterallly there
What does posterior spinal take out in the caudal medulla?
Dorsal column/medial lemniscus system (gracile and caudate nucleii)
What does anterior spinal artery take out in the caudal medulla?
A bit of the dorsal column/medial lemniscus system as well, becase at this level internal arcuates are taking the dorsal column axons over to the medial lemniscus, which here is anterior/ventral (actually kind of central) and medial
Will you get horners with a lesion of vertebral artery at caudal medulla? explain.
Yes. You get an ipsilateral horners. This lesion takes out spinothalamic tract, whcih is lateral and superficial here. But nereby is a descendign sympathetic control tract, the caudal extension of the medial forebrain bundle. Taking this out interrupts sympathetics which are descending to T1 to exit column and enter sypmpathetic chain ganglia. so you get an IPSILATERAL HORNERS
How do you know you are in middle medulla?
You see olivary nucleus
You don't see gracile and cuneate nucleii
What do the vertebral arteries supply mid medulla?
Everything except those lateral bumps--so, the inferior olivary nucleus, etc.
What supplies those dorsolateral bumps mid medulla?
Where is ST tract now at mid medulla?
Still lateral and superficial. But much of its supply is now coming from PICA instead of just vertebral.
Where is the caudal extension of the medial forebrain bundle now at the level of mid medulla?
Still with the ST tract, which is generally lateral and superficial. But also it's blood supply is largely PICA, like the ST (instead of vertebral).
Where is the descending nucleus and tracts of 5 mid medulla?
In those dorsolateral bumps
What supplies the descending/spinal nucleus and tracts of V?
What sypmtoms wiht a PICA infarct (think mid medulla)
1) You knock out descending nucleus of CN 5. So you lose pain and temp sensation of face, and this is ipsilateral since fibers don't dessucate until after leaving nucleus.
2) you knock out ST tract, which at mid medulla is supplied by PICA. This means you lose pain and temp sensation from contralateral side of the BODY, since these have ALREADY desuccated before hitting lesion.
3) you also get a HORNERS, beccause in knocking out ST you also hit caudal extension of medial forerain bundle, which carries descending sympathetic control. This is IPSILATERAL.
What kind of symptoms do you get with Lateral Medullary syndrome of wallenburg?
things including PICA infarct signs

1) ipsilateral loss of pain and temp sensation to the face
2) contralateral loss of pain and temp sensation to the body
3) ipsilateral horners
How do you know you are in upper medulla?
Little bit of olivary nucleus
the dorsolateral knobby things have gootten big
Where is medial lemniscus in upper medulla?
Medial to the olivary nucleus (dark black)
What supplies the PPRF in the caudal pons?
Basilar: AICA and long circumferential
What supplies spinothalamic tract and medial lemniscus in caudal pons?
Basilar: paramedians, AICA, long circumferential? look up
What supplies Trigem principal sensory nucleus and motor nucleus in mid pons?
Long circumferential brancnhes of basiliar (AICA)
What supplies the VPM?
Posterior cerebral
What could cause reduced pain, temp, vibratory sense, proprioception on one leg in one dermatome?
Lesion at dorsal root on one side.
Note on previous card: would just one root lesion give you a phenotype?
What would give you reduced touch and proprioception in one leg?
Defecit in one posterior spinal artery at L2, OR

a partial defecit in somethhing supplying gracile nucleus in lower medulla
Artery name for previous answer (what supplies gracile nucleus in caudal medulla)
Posterior spinal a
What could give you BILATERAL loss of pain, temp, vibration, proprioception, touch?
(unless you had succesive bilateral dorsal root lesions)

Some midline tumor in your paracentral lobule area pressing on both postcentral gyrii in leg/foot areas

OR maybe bilateral diabetic neuropathy
What gives you unlateral body AND FACE loss of pain, temp, toouch, vibration, propriocepption
Lesion in CONTRALATERAL internal capsule--everyting has desucated by that point. (Middle cerebral stroke)
What does VPL stand for?
Ventral posterior lateral (nucleus of thalamus)
What does VPM stand for?
Ventral posterior medial (nucleus of thalamus...gets info from face)
What is spared in an MCA infarct of internal capsule, and why?
Upper face movement spared due to bilateral cortical innervation of facial nucleus upper face neurons
What kind of label is HRP?
If you inject HRP into Postcentral gyrus, in ends up:
In VPM and VPL nucleii of IPSILATERAL thalamus
If you inject HRP into Right gracile nucleus in caudal medulla
Right Lumbar dorsal root ganglion (leg)
If you inject anterograde label into dorsal root ganglion, it shows up in:
The Ipsilateral dorsal column nucleus AND

spinal dorsal and VENTRAL (??) horn
If we inject anterograde tracer into left VPL of the thalamus, it shows up in:
Left (ipsilateral) postcecntral gyrus
If you inject anterograde label into one dorsal column nucleus in caudal medulla, it shows up in:
contralateral VPL of thalamus
If you inject HRP into left VPL of thalamus, it shows up in
Right dorsal column nuclei (ML/DC system) and right dorsal horn (cell body for spinothalamic)
In general, where do pathways that regulate automatic motor control descend?
The ventromdial regions of the spinal cord
(vestibulospinal and reticulospinal pathways)
In general, what are nurons that give rise to the automatic control wathways associated with?
cerebellum and basal ganglia
In general, where do pathways that regulate voluntary movement (esp in the corticospinal tract) descend?
The dorsolateral funiculus
What is the lateral corticospuinal tract often referred to as?
Pyramidal tract
In genneral, what does the CST connect?
Connects neurons of the cerebral cortex to interneurons and motorneurons in the spinal cord
Where is the desucation of the CST?
Lower medulla
What signs indicate CST lesions:
1) WEakness (hemiparesis) or paralysis (hemiplegia) on one side of body

2) Babinski sign positive in aduts (extension of big toe when the sole of the foot is stroked)

3) increased myotactic (stretch) reflexes)

4) Spasticity (increased muscle tone, increased resistance to muscle strech in extensor muscles of legs and flexors of teh arms)
Difference between spacticity and rigidity
Rigidity: consequence usually of damage to basal ganglia; characterized by increased ton in BOTH flexor and extensor muscles, not accompanied by inccreased strech reclexes)

Spasticity: increased muscle tone, resistance to strech in teh extensor muscles of legs and flexors of arm
What do lesions of CST above the pyramidal decussation produce?
Contralateral motor defecits (compared to lesions of the spinal cord, which produce IPSIlateral motor defecits)
Describe the MEDIAL CST
(aka Ventral CST)

1) starts in motor, premotor region.
2) no dessucation: bilateral
3) controls voluntary movement (axial)
What do corticobilbar tracts provide?
Descending control of voluntary facial and other cranial muscle movements
Where does corticobulbar tract originate?
Mostly in the face region of the precentral gyrus (near the lateral fissure)

Also from prefrontal and somatosensory cortices
Where does corticobulbar path take cortical inputs?
1) red nucleus
2) vestibular nuclei
3) cells of origin of the reticulospinal pathways
4) cranial nerve motor nuclei
5) other brainstem targets
What happens when you damage face region of the primary motor cortex or axons ABOVE te facial nucleus (e.g., the internal capsule)?
LOWER part of face paralyzed contralaterally
UPPER face completely ok, both sides

WHY? bilateral innervation of the forehead region
Corticobulbar tract summary:

1) Origin: motor, premotor, supplementary, somatosensory cortices
2) Decussation: bilateral, except for lower face
3) terminations: brainstem only
4) Function: volunatry movements of cranial muscles, sensory correction
Do lesions in the internal capsule/corona radiata produce sensory, motor, or both deficits?
Name 4 bulbospinal pathways descending in the ventral and ventrolateral white matter
1) rubrospinal
2) tectospinal
3) reticulospinal
4) vestibulospinal
Where does rubrospinal tract originate?
Magnocellular portion of the red nucleus
Where do rubrospinal tract neurons decussate? Then where do they go? How far down?
Decusssate Almost immediately after red nucleus.

Assume a DORSOLATERAL position in the brainstem.

Stay there inspinal cord, where they are joined by axons of the corticospinal tract.

Descends only through CERVICAL regions.
Where doe s rubrospinal tract get input?
The same regions of the frontal lobes that give rise to the corticospinal tract.
Where does tectospinal tract originate?
Pimarily in the superior colluiculus
Where does tectospinal tract project to?
Upper cervical levels
What does tectospinal tract help coordinate?
Involved in coordinating reflex orientation of the head and eyes to moving stimuli
What side of the body are the tectospinal targets?
Where do reticulospinal tracts originate?
Pontine and medullary reticular formation
What does the pontine reticulosppinal tract facilitate?
antigravity reflexes
What does the medullary reticulopinal tract do?
Facilitates the freein g of antigravity motoneurons from reflex control (opposite effect of pontine reticulospinal)
Which side of the body are pontine and medullary reticulospinal targets?
Where do vestibulospinal tracts originate?
Vestibular nucleii of the medulla
Where do the 2 components of the vestibulospinal tract run, and what are they involved in?
1) runs bilaterally and is involved in coordination of hea, neck, and eyes in space

2) runs ipsilaterally and provides positive tone to antigravity muscles
Where do axons involved in descending control of th eANS primarily arise?
The paraventricular nucleus of the ipsilateral hypothalamus
What 2 tracts to axons in autonomic descending pathways arise?
DLF: dorsal longitudinal fasiculus

MFB: medial forebrain bundle

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