4. Cont………
BRAIN is the most specialized tissue in the body and
it is almost entirely composed of nervous tissue .
It is enclosed in the protective covering called
meninges.
It has main three division _hindbrain
_midbrain
_forebrains.
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7. Hindbrain
It is also called rhombencephelon that occupies the
posterior fossa of cranial cavity.
It consists of A) myelenocephalon include medulla
oblongata & fourth ventricle
B) metacephalon include pons
&cerebellum.
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8. I. Medulla oblongata
It is the caudal portion of brain extend from foramen
magnum to the pons & pyramidal in shape.
Has two extremity :.A)the rostral that is toward the
pons
B) the caudal that continues with
medulla spinals.
Parts of medulla oblongata divided by anterior lateral
sulcus &posterior lateral sulcus in to three distinct
such as anterior ,meddle &posteriors.
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9. Cont……….
It has three surface such as
A) venteral surface of medulla is marked
by median fissure continues with that of cord &flanked by
longitudinally ridges& pyramids.
The caudal portion of the fissures(groove) is partially filled
by the decussately of the pyramids.
Pyramid is the longitudinally band fiber on either side of
the midline between the median fissures &the lateral one .
B)dorsal surface resemble the half spinal
cord &its rostra hay.
It form s the rhomboid fossa which is the floor of fourth
ventricle.
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10. Cont….
The dorsal medial sulcus is the contination of the
median sulcus of spinal cord&end at apex.
C)lateral surface it is marked by different
origin of cranial nerves. for example glosso pharyngeal
vagus & accessory nerves.
The medulla oblongata is the most vital part of the
brain because it is the control center for breathing,
blood pressure and heart beat among other
involuntary body functions
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11. II. pons
Is a thick transverse fiber tract divided in to bie
laterally symmetrically halves by a slight midline
depression.
It has three surface such as
A)ventral appear as large ,wide convex
protuberance decreasing in size laterally .
Marked by a slight depression in midline refered to as
basilar sulcus.
B)lateral consider by decrease in width that
continuous with the middle cerebella pedicle which run
caudodorsal direction & disappearing in the cerebllum.
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12. Cont…..
C) dorsal corresponding to rostra part of
rhomboid fossa.
The pons contains nuclei that relay signals from
the cerebrum to the cerebellum, along with nuclei
that deal primarily with sleep, respiration,
swallowing, bladder control, hearing,
equilibrium, taste, eye movement, facial
expressions, facial sensation, and posture.
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13. Internal anatomy of medulla
oblongata &pons
The principal feature on the internal anatomy of
medulla oblongata& pons are the nuclie of cranial
nerve ,olivary & potinc nuclie ,the formation of certain
reticular formation & certain ascending & desending
fibers tract that connect the spinal cord with high level
of the brain.
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14. cerebellum
The cerebellum ((Latin for little brain) is the second largest part of your
brain, and is located near the base of the brain. Constituent the larg
part of hindbrain.
Is roughly globular having much fissure & located above the pons
medulla.
Separet from cerebral hemispher by transvers fissure &tentorium
cereblli which contain it.
It consists of two larger part such as cerebral hemispher narrow ridge
named as vermis.
The body of cerebellum subdivided to rostral& caudal lobs by primary
fissures.
The rostral lobe sub divided in to small lingual. which is the rostral part
of the central nerve system by numerous fibers which make up the
cerebral pendicels such as
caudal cerebral pendicel that connect medulla &spinal cord
with cerebellum.
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15. Cont…….
Middle cerebrall pendicl
And rostral cerebral pendicle.
In the cerebellum the bulk of the gray substance is
arranged as external cortex that in colour the white
substance of medulla.
The cerebellum is involved in balance, equilibrium,
muscle tone, and the coordination of voluntary motor
movement.
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