Fine structure of the medulla oblongata (final version) Flashcards
I. Caudal part (closed part) of medulla
1. Which nuclei can you find in dorsal horn? Where will its axons go?
- The dorsal horn contain spinal trigeminal nucleus which is in the lateral direction (due to appearance of cuneate and gracile nuclei)
-> Axons of spinal trigeminal nucleus cross the midline ventral to central canal and ascend towards thalamus (VPM) => This will become trigeminal lemniscus which participate in the anterior trigeminothalamic tract (protopathic) - The Lissauer tract continues in the spinal trigeminal tract (next to spinal trigeminal nucleus)
I. Caudal part (closed part) of medulla
2. Spinal trigeminal nucleus is dislocated to lateral side of dorsal horn due to the appearance of 2 nuclei
=> What are they? Their paths?
They are the gracile and cuneate nuclei
- Axons of the neurons in the gracile and cuneate nuclei cross the midline as internal arcuate fibers and ascend on both sides of midline to thalamus (VPL)
=> This will become medial lemniscus
DCML pathway (Epicritic)
I. Caudal part (closed part) of medulla
3. Which nuclei can you found at the ventrolateral aspect of grey matter?
Inferior olivary nucleus found at the ventrolateral aspect of grey matter
-> axons cross midline and go to cerebellum via inferior cerebellar peduncle
=> This is olivocerebellar tract (plasticity and learning)
I. Caudal part (closed part) of medulla
5. The continuation of the lateral funiculus contains ____ (which tract?)
the spinothalamic tract (next to inferior olivary nucleus)
I. Caudal part (closed part) of medulla
5. Continuation of the spinal anterior funiculi contain __ (which tract?)
Continuation of the spinal anterior funiculi contain the corticospinal tract.
- Most of the corticospinal tract fibers cross the midline (pyramidal decussation) and descend contralaterally in the lateral funiculi
=> Have a role in voluntary control of limbs and body posture
I. Caudal part (closed part) of medulla
6. Can you find the group of motoneurons here? If yes, how is it subdivided?
YES!
The group of motor neurons is subdivided into ventrolateral and dorsomedial motor nuclei.
- Axons the the ventrolateral group (nucleus ambiguus) join the accessory and vagus nerve.
- Axon of the dorsomedial group (hypoglossal nucleus) form the hypoglossal nerve
I. Caudal part (closed part) of medulla
7. Identify
II. Rostral part (open part) of medulla
1. What happen to axons of nucleus ambiguus?
Axons of nucleus ambiguus join the vagus nerve & glossopharyngeal nerve
II. Rostral part (open part) of medulla
2. What happen to the central canal in rostral part of medulla?
It expands into 4th ventricle
II. Rostral part (open part) of medulla
3. Dorsal to the nucleus ambiguus and lateral to the hypoglossal nucleus, 2 new groups of neurons appear.
=> What are they? Their path?
- Dorsal vagal nucleus
- Lateral to the dorsal vagal nucleus is the lateral nucleus of ala cinerea, which is basically an extension of the nucleus of the solitary tract (viscerosensory nucleus)
II. Rostral part (open part) of medulla
4. What can we find Next to the ala cinerea?
we can find the area postrema which is…
- A vomiting center
- A circumventricular organ lacking BBB
- Having chemosensory activity
II. Rostral part (open part) of medulla
6. In rostral part, you can still see the nuclei that you have found in caudal part. What are they?
Lateral -> Medial
1. Sensory
- Spinal trigeminal nucleus - GSS
- Solitary nucleus - SVS (taste - baro-R)
2. Motor
- Nucleus ambiguus - branchiomotor
- Dorsal vagal nucleus - parasympathetic
- hypoglossal nucleus - Somatic
III. What is functional significance of medulla oblongata?
- Reflex control of cardiovascular & respiratory system
- Reflex control of swallowing and vomiting
- Important in phonation (control of tongue, larynx and pharynx)
IV. Identify this cross section (rostral part of medulla oblongata)
IV. Identify this cross section (rostral part of medulla oblongata)
