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MEDULLA OBLONGATA INTERNAL STRUCTURE

D. MEDULLA OBLONGATA INTERNAL STRUCTURE. BRAIN STEM. DORSAL SURFACE. VENTRAL SURFACE. CAUDAL MEDULLA ( LEVEL OF PYRAMIDAL DECUSSATION). FG. DMS. FC. GN. ST5. Central grey matter. CN. SN5. Central canal. DSC. PD. VSC. P. VMF. CAUDAL MEDULLA ( LEVEL OF PYRAMIDAL DECUSSATION).

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MEDULLA OBLONGATA INTERNAL STRUCTURE

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  1. D MEDULLA OBLONGATA INTERNAL STRUCTURE

  2. BRAIN STEM DORSAL SURFACE VENTRAL SURFACE

  3. CAUDAL MEDULLA(LEVEL OF PYRAMIDAL DECUSSATION) FG DMS FC GN ST5 Central grey matter CN SN5 Central canal DSC PD VSC P VMF

  4. CAUDAL MEDULLA(LEVEL OF PYRAMIDAL DECUSSATION) • DMS: Dorsal median sulcus • FG: fasciculus gracilis • GN: Gracile nucleus • FC: Fasciculus cuneatus • CN: Cuneate nucleus • SN5: Spinal nucleus of trigeminal nerve • ST5: Spinal tract of trigeminal nerve • P: Pyramid • PD: Pyramidal decussation • DSC: Dorsal spinocerebellar tract • VSC: Ventral spinocerebellar tract • VMF: Ventral median fissure

  5. CAUDAL MEDULLA(LEVEL OF PYRAMIDAL DECUSSATION) • GREY MATTER: • Sensory nuclei: Gracile, cuneate, spinal nucleus of trigeminal • WHITE MATTER: • Ascending tracts: Gracile, cuneate, spinal tract of trigeminal, dorsal & ventral spinocerebellar, spinal leminiscus • Descending tracts: Pyramidal & extrapyramidal tracts

  6. CAUDAL MEDULLA(LEVEL OF PYRAMIDAL DECUSSATION) • Pyramidal decussation:Most of the fibers of pyramid decussate then pass laterally & dorsally to form the lateral corticospinal tract that descend in the lateral white column of spinal & terminate in ventral horn cells of opposite side • Spinal nucleus of trigeminal:It lies in the lower part of pons, the whole medulla & extends to the 2nd cervical segment of spinal cord where it is continuous with substantia gelatinosa. It receives pain & temperature sensations from the face along trigeminal nerve

  7. CAUDAL MEDULLA(LEVEL OF PYRAMIDAL DECUSSATION) • Dorsal & ventral spinocerebellar tracts: They carry proprioceptive fibers to the cerebellum through inferior cerebellar peduncle (dorsal) & superior cerebellar peduncle (ventral) • Gracile &Cuneate tracts: They carry proprioceptive & fine touch sensations & end in Gracile & Cuneate nuclei (2nd order neurones in dorsal column tract)

  8. MID MEDULLA(LEVEL OF SENSORY DECUSSATION) DMS Central grey matter FG FC GN CN Central canal ST5 SN5 Internal Arcuate Fibers DSC M L VSC Sensory Decussation P VMF

  9. MID MEDULLA(LEVEL OF SENSORY DECUSSATION) • GREY MATTER: • Sensory nuclei: Gracile, cuneate, spinal nucleus of trigeminal • WHITE MATTER: • Ascending tracts: gracile, cuneate, spinal tract of trigeminal, dorsal & ventral spinocerebellar, spinal leminiscus • Descending tracts: Pyramidal & extrapyramidal tracts

  10. MID MEDULLA(LEVEL OF SENSORY DECUSSATION) • Gracile & cuneate nuclei: They are more prominent. Axons of cells of gracile & cuneate nuclei curve around the central canal as internal arcuate fibers then decussate forming the sensory decussation & ascend in the brain stem as medial leminiscus that end in the ventral posterolateral nucleus of thalamus • Pyramid: They are more prominent

  11. BRAIN STEM VENTRAL SURFACE DORSAL SURFACE

  12. ROSTRAL MEDULLA DCN 4TH V MV LV V H S ICP VCN M L F A D Vagus Nerve I.O. ML M Hypoglossal Nerve P VMF

  13. ROSTRAL MEDULLA • H: Hypoglossal nucleus • V: Dorsal vagal nucleus • S: Nucleus solitarius • A: nucleus ambiguus • MV: Medial vestibular nucleus • LV: Lateral vestibular nucleus • DCN: Dorsal cochlear nucleus • VCN: Ventral cochlear nucleus • ICP: Inferior cerebellar peduncle • I.O.: Inferior olive • D: Dorsal accessory olive • M: Medial accessory olive • MLF: Medial longitudinal fascisulus • ML: Medial leminiscus • P: Pyramid • VMF: Ventral median fissure

  14. ROSTRAL MEDULLA • GREY MATTER: • Motor nuclei: Hypoglossal, dorsal vagal, nucleus ambiguus • Sensory nuclei: Nucleus solitarius, medial & lateral vestibular nuclei, dorsal & ventral cochlear nuclei, spinal nucleus of trigeminal • Extrapyramidal nuclei: Inferior olive, medial & dorsal accessory olive

  15. ROSTRAL MEDULLA • WHITE MATTER: • Ascending tracts: Medial leminiscus, spinal leminiscus, spinal tract of trigeminal, ventral spinocerebellar tract • Descending tracts: Pyramidal & extrapyramidal tracts • Both ascending & descending tract: Medial longitudinal fasciculus • Inferior cerebellar peduncle: fibers connecting medulla to cerebellum

  16. ROSTRAL MEDULLA • Hypoglossal nucleus: It lies in the medial part of floor of 4th ventricle. It contains motor neurones innervating muscles of tongue (except palatoglossus) through hypoglossal nerve • Dorsal vagal nucleus:It lies in the floor of 4th ventricle , lateral to hypoglossal nucleus. It contains preganglionic parasympathetic neurones running in the vagus nerve • Nucleus Solitarius:It lies ventrolateral to dorsal vagal nucleus. It receive taste fibers from facial, glossopharyngeal & vagus nerves

  17. ROSTRAL MEDULLA • Nucleus ambiguus:It lies dorsal to inferior olivary nucleus. It contains motor neurones innervating muscles of pharynx, palate & larynx through glossopharyngeal, vagus & cranial part of accessory nerves • Medial & lateral vestibular nuclei:They lie in the floor of 4th ventricle, lateral to dorsal vagal nucleus. They receive afferent fibers from vestibular nerve • Dorsal & ventral cochlear nuclei:They lie dorsal (dorsal nucleus) & lateral (ventral nucleus) to ICP. They receive afferent fibers from cochlear nerve

  18. ROSTRAL MEDULLA • Olivary nuclear complex:It is formed of a large nucleus (inferior olive) & 2 smaller nuclei (medial & dorsal accessory olive). • Afferents: From cerebral cortex & spinal cord • Efferents: To cerebellum through ICP • Function: They are concerned with control of movement

  19. ROSTRAL MEDULLA • Medial longitudinal fasciculus:It consists of both ascending & descending fibers: • Ascending fibers: connect vestibular nuclei to nuclei supplying extraoccular muscles (occulomotor, trochlear & abducent nuclei). It coordinates movements of head & eyes • Descending fibers: connect vestibular nuclei to nuclei of ventral horn of spinal cord (medial vestibulospinal tract). It control body posture & balance

  20. ROSTRAL MEDULLA • Spinal leminiscus: It carries pain, temperature & touch sensations from the opposite side of body to ventral posterolateral nucleus of thalamus • Inferior cerebellar peduncle: It is formed of fibers connecting medulla to cerebellum

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