Nuclei/Tract Cross-Sections: Images from Semmelweis Flashcards by Kiva Mcfetridge

Midbrain

What type of nucleus is this?

Edinger-Westphal Nucleus - Accessory Oculomotor

General Visceromotor (parasympathetic, performs pupil constriction)

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Midbrain

What neurotransmitter is produced here?

Substantia Nigra

Dopamine

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Midbrain

Which funiculus of the spinal cord contains this pathway?

Rubrospinal Tract - see it coming from Red Nucleus and crossing

Runs through Lateral Funiculus (with the lateral corticospinal tract)

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Midbrain

What sensation is it involved in?

What type of nucleus?

What is the morphology of this neuron (multipolar, unipolar etc?)

Mesencephalic Trigeminal Nucleus

Proprioception of Head/Face

General Somatosensory

Pseudounipolar morphology

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Midbrain

Where do the central branches go?

What is unique about this tract?

Mesencephalic Trigeminal Tract

Central branches descend into pons, and the fibers synapse with the trigeminal motoneurons innervating the masticatory muscles

Forms the only monosynaptic reflex arc in the brainstem, creating the jaw jerk reflex when the jaw is extended

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Midbrain

What cranial nerves are involved in this pathway?

Between what places does it travel?

Medial Longitudinal Fasciculus (MLF)

Primarily involved in the directing eye movement via cranial nerves III, IV, VI, connecting them with the vestibular nucleus, also involving CN VIII for head movement information

Travels from the Interstitial Nucleus of Cajal to the cervical spinal cord

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Midbrain

What type of information does it carry, and to where?

Brachium of Inferior Collicle

Carries auditory information to the Medial Geniculate Body (MGB) of the thalamus

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What type of information does it receive?

Medial Geniculate Body (MGB) of (meta)thalamus

Not part of midbrain, but must have been drawn this way to show a connection between midbrain and thalamus

An intermediate connection in the auditory pathway, between inferior collicle and auditory cortex

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Midbrain

What tract(s) originate here?

What tract(s) terminate here?

Red Nucleus

Rubrospinal Tract (#3) originates from here and crosses in midbrain, then goes to affect lower motor neurons. Has limited function in humans, most of voluntary control is from corticospinal tract

Some branches called the rubro-olivary tract also go to the inferior olive (uncrossed pathway)

Dentatorubro tract terminates here; it comes from dentate nucleus of cerebellum

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Midbrain

What type of information do these fibers carry?

Where do these fibers originate from?

Where do these fibers decussate?

Where do these fibers go?

Medial Lemniscus

Carries epicritic information from the body

Contains the afferent fibers coming from gracile and cuneate nuclei (Dorsal Column)

Decussate in the medulla

Goes to Thalamus VPL, then to sensory cortex

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Midbrain

Which part of the internal capsule does this pass through?

Türck Tract (temporo-parieto-occipito-pontine)

Passes through posterior limb of internal capsule

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Midbrain

Which part of the internal capsule does this travel through?

Corticospinal Tract

Posterior Limb of internal capsule

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Midbrain

Which limb of the internal capsule does this pass through?

Arnold Tract (fronto-pontine)

Anterior limb of internal capsule

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Midbrain

Oculomotor Nerve (CN III)

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Midbrain

Tectospinal Tract (see the tract originating from tectum)

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upper medula

what type of nucleus?

What nerve(s) have fibers with this nucleus in this section?

Solitary nucleus and Solitary tract

Special Viscerosensory Nucleus (taste)

Nerves IX and X have afferent fibers to the solitary nucleus here in the medulla

Nerve VII has a connection more superiorly!

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upper medulla

what type of nucleus is it?

which cranial nerve(s) have fibers here?

2 dorsal vagal nucleus

aka medial ala cinera nucleus

General Visceromotor (parasympathetic)

Only Vagus

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upper medulla

What type of nucleus is it?

Hypoglossal nucleus

Somatomotor nucleus

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upper medulla

4 medial longitudinal fasciculus

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upper medulla

5 tectospinal tract

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upper medulla

unlabelled black line between 5 and 6

What cranial nerve(s) have fibers here?

What type of nucleus?

unlabelled line btwn 5 and 6

lateral ala cinerea nucleus

Glossopharyngeus and Vagus have sensory fibers that go here

General Viscerosensory (GVS) - the only nucleus like this!

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upper medulla

6 area postrema

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upper medulla

which order neuron is this?

7 nucleus gracilis

second order neuron

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upper medulla

8 nucleus cuneate

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upper medulla 9

9 inferior vestibular nucleus

upper medulla 10 What type of nucleus is here? What pathway does the tract take, and to where?

10 **Tract** and **nucleus** of **spinal trigeminal** **General Somatosensory** for protopathic information about the head Travels via the **Trigeminal Lemniscus** to the **Thalamus VPM**

upper medulla 11 is this path crossed?

11 **Posterior spinocerebellar tract** **uncrossed**

upper medulla 12

12 olivocerebellar tract

upper medulla 13 what type of nucleus is this? what cranial nerve(s) have fibers here?

13 **Nucleus Ambiguus** **Branchiomotor/SVM** cranial nerves **IX, X, XI**

upper medulla 14 With what type of fibers does the pathway originating from here end in the cerebellar cortex?

14 **Inferior Olivary** nucleus Ends in **Climbing Fibers** (IO means inferior olive in image below)

upper medulla 15

15 olivocerebellar fibers

upper medulla 16

16 internal arcuate fibers as they approach the lemniscal decussation, after which they become the medial leminiscus

upper medulla 17 What type of fibers run through here? With what type of neurons do they synapse when they terminate?

17 **Pyramids** **Corticospinal tract** Terminates with synapse to **alpha motor neurons**

upper medulla 18

18 internal arcuate fibers

upper medulla 19

19 hypoglossal nerve

upper medulla 20

20 lemniscal decussation and olivocerebellar decussation

upper medulla 21

21 spinothalamic tract

upper medulla 22

22 ventral spinocerebellar tract (gowers)

upper medulla 23 where are these nerve(s) coming from?

23 **glossopharyngeus** and **vagus** nerve coming from the **nucleus ambiguus**

upper medulla 24 where are these nerve(s) coming from?

24 **glossopharyngeal** and **vagus** nerves coming from **lateral ala cinerea**

Caudal Medulla 1 What type of nucleus is this?

1. **Hypoglossal** Nucleus A **Somatomotor** nucleus (hypoglossal nerve)

Caudal Medulla 2 What type of nucleus is this? From what cranial nerves does it receive information? To where does it send information?

2. **Solitary** Nucleus **Special Viscerosensory** Nucleus (taste) Receives afferent fibers from CN **VII, IX and X** Sends information to **Thalamus VPM**

Caudal Medulla 3 Which neurons are these in sequence? What neurons terminate here? What neurons start here?

3. **Gracile Nucleus** **Second** order neurons. **Gracile Fasciculus terminates** here, **Internal arcuate fibers** **start** here, then cross and become medial lemniscus.

Caudal Medulla 4 What type of information is carried here? Where is it carried to?

4. **Cuneate Nucleus** **Epicritic** information from the cervical nerves (**upper body**) Goes to **Thalamus VPL** via the medial lemniscus

Caudal Medulla 5

5. Spinal Trigeminal Tract

Caudal Medulla 6 What is this type of nucleus? *What is the continuation of the nucleus when it goes inferiorly?*

6. **Spinal Trigeminal** Nucleus **General Somatosensory** (GSS) In the spinal cord, it becomes the **Substantia Gelatinosa** (Rexed Lamina 2)

Caudal Medulla 7 What order are these neurons?

7. **Internal Arcuate Fibers** **2nd** order neurons

Caudal Medulla 8 Where does this pathway end? What type of information does it carry? Which neuron is it in sequence?

8. **Spinothalamic** Tract Ends at **Thalamus VPL** Transmits **protopathic** sensation (pain, temperature, crude touch) for the body 2nd neuron in sequence

Caudal Medulla 9 What nerves does it join with?

9. Nucleus Ambiguus **IX, X, XI nerves**

Caudal Medulla 10

10. Inferior Olivary Nucleus

Caudal Medulla 11

11. Pyramidal Decussation

Caudal Medulla 12

12. Decussation of Medial Lemniscus

Pons 1

1. Superior Cerebellar Peduncle

2 & 11, what is this pathway? Which peduncle does it travel through?

2 (and 11). **Pontocerebellar** Tract Travels through **middle** cerebellar peduncle

3 (medial to the structure in #5) What type of nucleus is this?

3. **Motor Trigeminal** Nucleus **Branchiomotor** / **Special Visceromotor**

4 Which information does this carry? What type of fibers does this path end in? Does it cross?

4. **Ventral Spinocerebellar** Tract (Gowers) Carries **proprioceptive** sensibility Ends in **mossy** fibers It crosses twice (once in the anterior commissure, once in the cerebellum) and so the cerebellum still receives information from the same side of body

5 ## Footnote hard to see, but it's the one that's lateral to #3 and covered by a giant arrow on that side of the picture What type of information is carried? Where does this nucleus send its fibers, and via what pathway? Crossed or uncrossed?

5. **Chief Sensory Trigeminal** Nucleus (Pontine/Principal) Sends **epicritic** information from the head to the **Thalamus VPM** via the **Dorsal Trigeminal Lemniscus** (don't confuse with the just Trigeminal Lemniscus!) **Crossed** pathway

6. Brachium Pontis

7. Trigeminal Nerve (see its connections with the trigeminal nuclei)

8. Medial Lemniscus

9: Which two types of tracts are seen? Which part of the pons contains these fibers?

9. **Corticospinal** tracts & **Corticopontine** tracts Corticospinal tracts keep going through pons, Corticopontine tracts synapse here with the pontine nuclei Within the **basis** of the pons

10. Pontine Nuclei, whose fibers go on to the pontocerebellar tract

12. Spinothalamic Tract

13 Where do these fibers travel to?

13. **Lateral Lemniscus** Fibers go to **Inferior** Collicle

14 What type of neurotransmitter is produced here?

14. **Locus Ceruleus** **Norepinephrine** produced here (involved in stress)

15 what is the origin of these fibers? where do these fibers end?

15. **Central Tegmental Fascicle** / Tract Comes from **Red Nucleus** Goes to **Inferior Olive**

16. Tectospinal Tract

17. Medial Longitudinal Fascicle

Spinal Cord 1

1. Lissauer Tract

2. Posterior Spinocerebellar Tract

3 What system is this a part of?

3. **Cruciate** (posterior) **Corticospinal** Tract Part of **pyramidal** system

4. Rubrospinal Tract

5. Anterior Spinocerebellar Tract

6. **Spinothalamic** Tract (here shown as one, but normally there is an anterior and lateral branch of the spinothalamic tract within the spinal cord)