Download Medulla, int. f2009-06-21 07:342.6 MB

Dr. Ahmed Fathalla Ibrahim
BRAIN STEM
VENTRAL SURFACE
DORSAL 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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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
CAUDAL MEDULLA
(LEVEL OF PYRAMIDAL DECUSSATION)
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GREY MATTER:
Sensory nuclei: Gracile, cuneate,
spinal nucleus of trigeminal
• WHITE MATTER:
1. Ascending tracts: Gracile, cuneate,
spinal tract of trigeminal, dorsal &
ventral spinocerebellar, spinal
leminiscus
2. Descending tracts: Pyramidal &
extrapyramidal tracts
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
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)
MID MEDULLA
(LEVEL OF SENSORY DECUSSATION)
DMS
FG
FC
GN
CN
Central grey
matter
Central canal
ST5
SN5
DSC
M
L
VSC
Internal
Arcuate Fibers
Sensory
Decussation
P
VMF
MID MEDULLA
(LEVEL OF SENSORY DECUSSATION)
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GREY MATTER:
Sensory nuclei: Gracile, cuneate,
spinal nucleus of trigeminal
• WHITE MATTER:
1. Ascending tracts: gracile, cuneate,
spinal tract of trigeminal, dorsal &
ventral spinocerebellar, spinal
leminiscus
2. Descending tracts: Pyramidal &
extrapyramidal tracts
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
BRAIN STEM
VENTRAL SURFACE
DORSAL SURFACE
ROSTRAL MEDULLA
DCN
4TH V
MV
LV
VH
S
VCN
ICP
A
D
Vagus
Nerve
Hypoglossal
Nerve
I.O.
M
L
F
M ML
P
VMF
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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
ROSTRAL MEDULLA
• GREY MATTER:
1.Motor nuclei: Hypoglossal, dorsal
vagal, nucleus ambiguus
2.Sensory nuclei: Nucleus solitarius,
medial & lateral vestibular nuclei,
dorsal & ventral cochlear nuclei, spinal
nucleus of trigeminal
3.Extrapyramidal nuclei: Inferior olive,
medial & dorsal accessory olive
ROSTRAL MEDULLA
• WHITE MATTER:
1.Ascending tracts: Medial leminiscus,
spinal leminiscus, spinal tract of
trigeminal, ventral spinocerebellar tract
2.Descending tracts: Pyramidal &
extrapyramidal tracts
3.Both ascending & descending tract:
Medial longitudinal fasciculus
4.Inferior cerebellar peduncle: fibers
connecting medulla to cerebellum
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
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
ROSTRAL MEDULLA
• Olivary nuclear complex: It is
formed of a large nucleus (inferior
olive) & 2 smaller nuclei (medial &
dorsal accessory olive).
1. Afferents: From cerebral cortex &
spinal cord
2. Efferents: To cerebellum through ICP
3. Function: They are concerned with
control of movement
ROSTRAL MEDULLA
• Medial longitudinal fasciculus: It
consists of both ascending & descending
fibers:
1. Ascending fibers: connect vestibular nuclei
to nuclei supplying extraoccular muscles
(occulomotor, trochlear & abducent nuclei).
It coordinates movements of head & eyes
2. Descending fibers: connect vestibular
nuclei to nuclei of ventral horn of spinal
cord (medial vestibulospinal tract). It
control body posture & balance
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