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119 Cards in this Set
- Front
- Back
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Are the hindbrain and the brainstem the same thing?
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No
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Draw out which structures belong to the hind brain vs brainstem. Mnemonic?
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brain stem is in one row like the stem of the spinal cord.
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Rhombencephalon is a synonym for what?
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Hind brain.
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What borders the medulla superiorly and inferiorly?
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ABOVE- pontine-medullary sulcus
BELOW- pyrimidal decussation |
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Can I get a real pic of a medulla here?
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What is the longitudinal groove between the pyrimidal swellings called?
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the central sulcus
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Side image of medulla? What does it look like?
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Looks like it is a part of the spinal cord tapering out.
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Why does this shape make sense for the medulla?
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because of how you imagine the nuclei and ventricles of the medulla just being stretched out versions of the spinal cord.
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What are the 4 major connection systems related to the medulla? (draw them out)
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ascending (dorsal), descending (ventral), posterior cerebellar, anterior cranial nerves.
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Where in the medulla is the reticular formation located?
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deep central portion
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Where are the fibers from the reticular formation going?
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Upwards to the thalami.
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Draw where the reticular formation is from a lateral view?
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what is the nickname for the reticular formation>
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the switch of the cerebral cortex
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Are your ears still sending impulses to the cortex when you sleep? Why can' you hear it?
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Yes, but the cortex is off because the reticular formation is down.
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What do you mean by "down"?
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It is not sending activating NT's in it's ascending tracts
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What is one of the reasons that people become vegetables?
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damage to the reticular formation or its connections.
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Specifically, where do the ascending fibers from the RF go to synapse?
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They synapse at the intralaminar nuclei of the thalamus, which then sort and relay the info to all over the cortex.
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What are the very vital autonomic centers located in the reticular formation in the medulla?
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Vasomotor center
Respiratory center Cardiac centers Gastrointestinal centers |
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Why is hanging someone so dangerous?
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You break the AA which is right at the medulla and shut off these vital centers.
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Why are medullary tumors more lethal than cerebral tumors?
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Same reason. If you take away the whole cortex, you can still survive off the vital centers of the medulla
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What type of important drugs that work on the vasomotor and cardiac centers in the medulla?
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centrally acting anti-hypertensive drugs
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What is the area postrema?
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the area that senses noxious substances in the blood and relays it.
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Draw out these 4 centers.
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Draw and nararate how noxious substances in the blood may lead to nausea and vomiting signals in the medulla.
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Loose BBB --> Area postrema --> Chemo Trigger Zone --> Center for autonomic control of GI tract
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How do I use this to remember where the autonomic GI tract center is?
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It has to be posterior and close to the area postrema for this reflex to happen.
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Which parts of this relay system are immediate vs must having to pass a threshold?
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area postrema --> chemotrigger zone = needs to reach a threshold
CTZ --> GI center = immediate |
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What reflex in the GI tract happens when the area postrema is activated?
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reverse peristalsis
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What reaction do you get with weak vs strong reverse peristalsis?
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weak- nausea
strong- vomiting |
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ASCENDING SYSTEMS IN THE MEDULLA
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WOOT!
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Where are the nuclei of the dorsal column exactly?
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exactly at the bottom of the medulla
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Draw the levels at which the dorsal nuclei happen and the internal arcuate fibers cross from a frontal view.
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What would you see of the dorsal column in a transsection of the mid medulla all the way to the midbrain?
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the medial laminisci
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What would happen if you had a lesion of the dorsal mdalities in the upper modality?
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loss of contralateral fine touch and proprioception
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Draw how the anterolateral system passes through the medulla from a frontal view. What other tract joins with them?
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they join at the medulla at the spinal leminiscal pathway and join with the spinotectal path.
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What is the lateral leminiscus?
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The pathway going from the two cochlear nuclei to the inferior colliculi.
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Draw out the pathway to the lateral leminisci.
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Would the lateral leminiscus be present in the medulla? Why?
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No because the cochlear nuclei that feed it are in the pontine-medullary junction.
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Would you find the lateral leminisci in the upper part of the midbrain? Why?
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No because they terminate at the inferior colliculi.
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What is the 4th leminiscus?
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the trigeminal leminiscus taking sensation from the face.
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Where is the trigeminal nerve located?
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in the pons
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So what are the main ascending pathways through the medulla?
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medial leminiscus and spinal leminiscus.
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So what can you say about the term leminiscus?
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It refers to sensory tracts.
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DESCENDING SYSTEMS IN THE MEDULLA
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OK!
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Draw how descending motor tracts pass through the medulla.
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What two tracts were displayed here?
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anterior and lateral corticospinal tracts
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What anatomical landmark are these descending motor tracts responsible for?
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The pyrimidal swellings.
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CEREBELLAR SYSTEMS IN THE MEDULLA
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ALRIGHT!
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What are the six main systems in the medulla to the cerebellum?
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1. cuneatocerebellar tract
2. dorsal spinocerebellar tract 3. ventral spinocerebellar tract 4. Rubro-olivary cerebellar tract 5. Cortico-arcuate cerebellar tract 6. Reticulo cerebellar pathway |
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Draw a lateral view of where all these cerebellar tracts enter the cerebellum.
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Draw out the lateral view of the cuneato-cerebellar pathway with it's nucleus and tracts.
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Describe how the spinocerebellar pathways work in terms of how they enter into their tracts?
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Enter and synapse at the same level dorsal root onto clarke's column or accessory cuneatus --> travel to their respective tracts on same level (ventral cross, dorsal don't)
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Through what structure does the cuneatus cerebellar tract go through?
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The inferior cerebellar peduncle.
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How do you remember that clarke's column is for the spinocerebellar tracts and don't cross obliquely like the anterolateral tracts?
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Lewis and Clarke love to travel, but must be very coordinated to do that (no dystaxia) and they always cross at the same level to not get lost.
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How do you remember that positive Romberg's is a dorsal column lesion and dystaxia is a spinocerebellar/cerebellar lesion?
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Just think about Bruce Friedrich with his B12 deficiency, syphilis, and autosomal recessive fridreich's ataxia with a positive Romberg's sign.
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What are the outward differences between dorsal column and cerebellar related lesions?
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cerebellar- can't coordinate movement even with eyes open
dorsal column- can use eyesight to make up for decreased proprioception |
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How far up the brainstem do the ventral vs dorsal spinocerebellar tracts go?
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ventral- up to the midbrain because they enter through the superior cerebellar peduncle and cross afterwards.
dorsal- up to the medulla because they enter through the inferior cerebellar peduncle ipsilaterally |
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Draw the rubro-olivary cerebellar tract and how it goes into the cerebellum from the front.
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Draw a lateral view of the cortico-pontine-cerebellar tract. Include which peduncle it goes through.
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Narrate the cortico-pontine-cerebellar tract.
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Each lobe has a tract which goes to the pontine nuclei located ventrally. They then go to the cerebellum through the middle cerebellar peduncle.
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Draw in the arcuate nuclei from a side view
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Essentially what are the arcute nuclei?
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Inferiorly displaced pontine nuclei.
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Draw where the arcuate nuclei are in relation to the medulla in a transection. Why are they called arcuate?
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They look like arcs in a transection.
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Draw a laterla view of how the fibers from the arcuate nuclei go into the cerebellum. What is this pathway called?
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What is the central tegumental pathway? Where does it begin and end?
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A tract that travels through the medulla and pons that starts in the NTS and ends at the ventral posterior medial thalamus.
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What fibers does the central tegumental pathway it contain? Do they all travel the whole length of the tract?
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1. rubro-olivary tract
2. reticulo-thalamic tract 3. taste pathway from NTS (only one that travels the whole pathway) |
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Draw a lateral view of the fibers travelling through the central tegumental pathway.
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Draw out the pre/post olivary sulci.
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What system should ythink of when you look at either creatinine OR BUN?
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renal only
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Draw a transection of the medulla and draw the nuclei and fibers for CN 12.
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Draw a transection of the medulla and draw the nuclei and fibers for CN 10. Name of these nuclei?
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Dorsal nucleus of vagus.
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What is another name for the dorsal nucleus of vagus? What does it do specifically?
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the parasympathetic nucleus. It gives the vagus nerve all of it's autonomic fibers.
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What kinds of things does the vagus carry besides sutonomic function?
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special sensations like taste.
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What is the nucleus just lateral to the vagus>
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Nucleus tractus solitarius
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What does the part of the NTS closer to the vagus nucleus do vs the more lateral part?
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closer- general visceral afferents (baroreceptors and other stuff from the trunk)
further- special visceral afferents (taste) |
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Does the dorsal nucleus of vagus have sensory or motor fibers?
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motor only
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But the vagus nerve is both motor and sensory! How do you make sense of this?
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The sensory fibers go to the nucleus tractus solitarius next door!
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Draw out the vagus connection to the NTS!
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Why was the NTS so happy?
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Because all the taste sensations go here!
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What are the branchial motor fibers?
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All the motor fibers going to the larynx, pharynx, and soft palate.
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What nerve and nucleus do these fibers come from?
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The vagus nerve and the special visceral efferent nucleus (nucleus ambiguus)
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Can you draw the nucleus ambiguus and it's fibers to the vagus nerve?
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Why is this nucleus called ambiguus? (multiple reasons)
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1. It is out of place from the other CN nuclei so it confused scientists
2. It controls semivoluntary actions (make up your mind!) |
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What other fibers does the nucleus ambiguus give off?
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the other vocal fibers. CN 9 and CN11
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Specifically what part of CN 11 comes off of here? What does it join with shortly afterwards?
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Cranial part of CN 11 (accessory nerve) which soon joins in with the vagus.
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Where do the 9th and 11th nerves come off the ambiguus compared to the 10th?
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9th above
cranial part of 11th below |
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What can happen to your heart and throat when you clean your ears?
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our heart rate can go down and you may cough/get a tingle in your throat.
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Why would this phenomenon happen?
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The vagus nerve has a branch for the external ear (tympanic branch of vagus). When pain, touch, or temperature reaches this area, it can activate the vagus efferents.
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What nucleus do the tympanic branches of the vagus come from? Mnemonic?
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The same nucleus that records all pain, temperature, and touch from the head, THE TRIGEMINAL NUCLEUS!
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How do you remember that it is the spinal nucleus of the trigeminal nerve that receives the pain signals?
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it is embryologically a continuation of the substantia gelatinosa (anterolateral pain and temperature pathway)
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Draw the spatial relation of the substantia gelatinosa and the trigeminal nerve.
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Does the trigeminal nucleus only get senosry fibers from the trigeminal nerve?
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No
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Draw in the other cranial nerves that bring in pain and temperature to the spinal part of the trigeminal nucleus.
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7, 9, 10
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What parts of the head are the 7, 9, and 10th CN's bringing in sensation from respectively?
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7- small part of ear
9- posterior 1/3 of tongue and tonsils 10- external ear |
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What do the tracts of all the different trigeminal nerve merge into? Where do they all end up?
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They merge into the trigeminal leminiscus which ends up in the same area that taste does, the ventral posterior medial thalamus.
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How do you remember the VPM thalamic nuclei function in relation to the VPL function?
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You turn your head (trigeminal) around to lick (taste) your wounds on your body (spinal sensory)
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Draw in the connections that CN 9 makes in the medulla nuclei.
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Basically what nuclei does CN 9 connect to?
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All of the same ones as he vagus nerve (that copy cat!)
Nucleus abiguus, both sides of NTS, and spinal part of trigeminal nucleus. |
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Draw in the connections of cranial part of CN 11.
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Narrate what just happened.
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The cranial part of CN 11 comes out of the nucleus ambiguus (to help with vocal control) and merges quickly with the vagus (what a trendsetter!)
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Are the vestibular nuclei just in the medulla?
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No, they are partially in the pons too!
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Draw a frontal view of how the 8th CN's attaches to it's nuclei.
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Draw where the CN 8 nuclei are in relation to all the other nuclei.
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Which nuclei in the medulla have only one nerve connection?
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hypoglossal nuclei and dorsal vagus nuclei
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Why are we able too coordinate gaze so well?
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Because all the eye movement nuclei are connected by a central tract.
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What is this tract called?
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Medial longitudinal leminiscus
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Describe and draw the location of the medial longitudinal leminisci?
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it is a paired tract that is in the center of the brainstem and spans it's whole length.
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What are the three sections of the medulla from bottom to top?
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1. level of pyrimidal decussation
2. level of dorsal decussation (internal arcuate) 3. mid olivary |
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Do the pyrimids or olives extend more posteriorly? How do you remember this?
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The pyrimids because they lead into the descending motor tracts and so last the whole medulla.
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Draw the three levels and label them.
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Draw the transection of the medulla at the level of the pyrimidal decussation.
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Narrate what just happened.
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The motor fibers that cross go posteriolaterally. dorsal column fasiculi, spinocerebellar tracts, and lateral spinothalamic tracts are all headed up. medial longitudinal leminiscus is paired and present in the middle. Central canal right in from of the dorsal column nuclei/fasicles. Most inferior CN are present (spinal CN 11)
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Why did the lateral fibers decussate backwards?
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They can't go any more anterior and they need to go back to line up with the lateral tract (except axial motor fibers)
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Draw the transection at the level of the internal arcuate fibers. (mid-lower medulla right before the inferior cerebellar peduncle)
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Narrate what just happened.
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dorsal column nuclei decussated, central canal becoming 4th ventricle, bottom of olives appear, bottoms of CN 12 nuclei and ambiguus nuclei appear. There is a connection of lowest nerve of ambiguus (cranial CN11)
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So which of the cranial nerve nuclei descend most inferiorly?
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Ambiguus and CN 12 nucleus.
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Which is the only one to give off nerves at the level of the internal arcuate fibers?
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ambiguus
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Draw the mid olivary level of the medulla.
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Same thing as I've been drawing this whole time!
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In these past 3 drawings, what did I actually mean to put when I drew the "lateral spinothalamic tract"?
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The spinal leminiscus because it has already joined with the anterior spinothalamic and spinotectal pathways at this point.
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how do you remember that cutting off the spinocerebellar tracts does not result in a positive Romberg's sign?
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Because the cerebellum is blind anyways so removing vision would not cause it to mess up anymore.
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