Medulla

Question 1

بسم الله الرحمن الرحيم
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Mention part of medulla

Answer 1

Closed medulla where central canal is still present and it is the caudal part
has to levels :
Level of motor decussation caudal
Level of Sensory decussation rostral
Open Medulla where the central canal is replaced with 4th ventricle and this part represents the floor

Question 2

Internal features of the medulla ?

Answer 2

Pyrmidal decussation
Sensory decussation :decussation of internal arcuate fivers to form medial lemisci
Spinal Nucleus of trigimnal: replacing substania gelations
Descending fibers of trigiminal tracts :replacing lissaure’s
Reticular Formation
4th Ventricle :Instead of Central canal

Question 3

motor decussation explain

Answer 3

it is in medulla
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The corticospinal ppyramidal tracts fibers has 3 pathes:
1-90% crossed to the other side as lateral corticospinal
2-8% not cross in the medulla and descends in ventral corticospinal tract then decussate in Spinal cord
3-2% from ipislateral anterolateral corticospinal tract
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Motor decussation for Voulntary control of contlateral side of body to the cerebral cortex giving the pyramidal tract

Question 4

Course to form sensory decussation

Answer 4

The gracile and cunate fibers turns anteromedially in relation to the central gray then decussate and ascends as medial lemnisci with the lamination: Gracile : saceal lubmar lower thoracic in antrior
but cunate in posterior
terminating in VPLN Of thalamus

Question 5

Mention Nuceli in Medulla :

Answer 5

Accessory cunate
Arcuate
Reticlar formation nucleus
OLivary nuclei complex
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Nuceli for lower 4 cranial nerves
9 10 11 12

Question 6

Accessory cunate fibers explain

Answer 6

Lies lateral rostral to the cunate nucleus
giving cunocerebellar dorsal external arcuate fibers to cerebellum
It is Equivelnt to Clarkes nucleus receving unconsicous prorpiceptive impulses from upper limbs
receving from cervcal and thoracic spinal ganglia

Question 7

Arcuate nucleus explian

Answer 7

it is found ventral to pyramid
it is contiunation of pontine nuclei
receving fibers from Cortex sends to cerebellum through ICP SENDS?
Ventral Extrenal Arcuate fibers

Question 8

Spinal trigimenal Nucelus explian

Answer 8

Medial to spinal trigimenal tract
as afferetns to it
the efferents are 2ndry trigimeal axons from this nuclei CROSS TO other site then pass Trigimnotalamic tract to the VLMN of thalamus to cortex

extedning from pons to C2

Question 9

Spinal trigimnal tract

Answer 9

afferent trigimnal root fibers from trigimnal ganglio to enter the pons
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descends dorsolaterally in pons and medulla till c2 the spinal nucleus of trigiminal decreasiing in size as descending to reach the nuceli
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Receeving pain and temperature from face

Question 10

Reticular formation

Answer 10

it is mixed grey and white matter as upward conintation from spinal cord to the whole length of brain stem from mototr ducssation of medulla to upper mid brain

Question 11

Connections of Reticular formation

Answer 11

Afferents:
-Spinal cord
-Cerebral cortex
-Deep Cerebellar nuclei
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effeetnts:ascending to talamus through central tegmental tract
descednding to the spinal cord to from Reticulspinal tract medullary

Question 12

Reticular formation controls ?

Answer 12

1-The movements of muscles through reticulospinal tracts
2-Autonomic and endocrine
3-Visceral and somatic sensation
4-Arousal and Conscoussness
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Question 13

Open medulla is cc by ?

Answer 13

appeareance of fourth ventricle and its elevations:
medial Hyoglossal trigone
intermidiate Vagal trigone : Dorsal motor nucelis of vagus + Solitary nucleus
-lateral vetsibular trigone
apperance of ICP
apperance of main Inferior Olivary nucleus

Question 14

Explain inferior olivary nuclei

Answer 14

Formed of
Main inferior olivart
Medial and dorsal accesoory olivary
afferents:
Cerebral cortex
Brainstem vestivbular + Spinal Nucleus of Trigeminal
Spinal cord to accessories
Rubro-olivary from red nucleus
Efferetns:
Olivocerebellar fibers working as climbing fivers activating dendrites of perkinje cells in mloeuclar layer of cerebellar cortex contralaretal cerebellum fooor motor learning
through ICP

Question 15

ICP explain

Answer 15

connecting cerebellum to medulla
has afferents A2SVO2R
EFFERETNS VO2R
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Afferents :
Ventral External arcuate fibers from arcuate nuelcues
Dorsal external arcuate fibers from the cunocerebellar
Spinocerebellar from ipsis lateral clarkes
Vestbilocerebellar
Olivo-cerebellar
para olivo-cerebellar
Reticlo-cerebellar
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Efferents:
Cerebello vestibular
cerebello Olivary
Cerebello-reticular

Question 16

asending and desending tracts in medulla

Answer 16

M2S2D
Medial lemiscai]
MLF
Spinal tract and nucleus of V
SpinoThalllllammmmmic
Dorsal spinocerebellum through ICP

Question 17

Explain corticonuclear tracts

Answer 17

From post and paracentral gyri
to the cranial nerve nuclei or by intercalated neurons theres
They mostly cross the midline

Question 18

The Nuclei of Cranial nerves recives bilaterally exceptr form ?

Answer 18

Facial nucleus from the lower part of face
hypoglosssal nucleus from genioglossus

Question 19

describe hypolgossla nucelus ?

Answer 19

it is in medulla deep to hypogloosal trigone extending to closed medulla
fibers supllying the all muscles of tongue exept palatoglossus
receving bilateral innervation except from genioglossus of protrution of tongue contralateral only
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connections : Bilateral corticoNucelar fibers except from the genioglossus of tongue protrusion contralateral only
Reticular formation
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Question 20

Accessory nucelus 11 explain

Answer 20

in medulla
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has two parts
spinal + cranial
spinal from the AHCs of the upper 5cervical segments up to medulla
for Sternomastoid + Trapezius
Cranial : from the lower part of Nucleus ambigous giving 11 nerve supplying muscles of palate except tensor palate / pharynx except stylophayngeus/ larynx
Bilateral corticobulbar or nuclear fibers

Question 21

compare between vagal and glosspharyngeal Nuclei

Answer 21

Vagal :
Dorsal motor nucelsu of vagues : to smmoth and cardiac muscles abdomen and thorax
Nucleus ambiguis : lowerpart gives mootr vagal for pharynx larynx osephoagus upper
Nucelus Solitarus : sensations to Tongue epiglottis organs supplieed by vagus
Spinal Nucelus of V: take from the auriclar branch of vagus sensations of back of ear and the external auditory meatus
Glossopharyngeal
inferio salivatory nucelus :
to Parotid after otic ganglion relay
Nucelus ambigus upper part giver motor of glosso for styolophayngeus
Nucelus soliartus : sesnations of post 1/3 of tongue - tonislis - pharynx - eucthican tube
Spinal Nucelus of V :take from fibers of 11 sensations of post 1/3 tonugs tonisllis orophaynx and auditory tube and middle ear

Question 22

functions of medulla ?

Answer 22

CN nuceli for vital functions as heart rate and respiration
Ascending and desnding tracts connectin spinal cord to higher brain centers

Question 23

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