Introduction to brain stem.pdfffffffffffff

Histo

3. Introduction to brain Stem
1-Parts of the brain stem.
2-Boundaries of brain stem.
3-Fourth ventricle.
4-Cranial nerves & their nuclei.
5-Clinical hint.
Dr Iman Nabil 3

4. Brain stem
•Three parts:
1-Midbrain.
2-Pons.
3-Medulla oblongata.
Dr Iman Nabil 4

5. Boundaries of Brain stem
1-Superiorly: The midbrain is
continuous with the forebrain
(thalamus, hypothalamus& cerebral
hemispheres).
2-Inferiorly: The medulla is continuous
with the spinal cord.
3-Posteriorly:
The pons& medulla are separated from
the cerebellum by the fourth(4
th
)
ventricle.
Dr Iman Nabil 5

6. Cerebellar peduncles
•Posteriorly: the midbrain, pons&
medulla are connected to the cerebellum
by the superior, middle and inferior
cerebellar peduncles respectively.
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7. Fourth ventricle
1-Below: continues with the central
canalof the spinal cord, which traverse
the lower part of the medulla.
2-Cranially: continues with the
cerebral aqueduct, which passes
through the midbrain.
3-Anteriorly: Medulla&pons.
4-Posteriorly: cerebellum.
Dr Iman Nabil 7

8. Dr Iman Nabil 8
•It is formed of floor, roof& lateral walls.
1-The floor of the 4
th
ventricle(rhomboid fossa):
Itis the ventral surface.
It is formed by the pons superiorly& upper medulla
inferiorly.
2-The roof of the 4
th
ventricle:
Itis the dorsal surface, it corresponds to the ventral surface
of the cerebellum.
It has a tent-like shaped and is divided into:
a-Superior part: formed by the superior medullary valum&
superior cerebellar peduncles.
b-Inferior part: formed by the inferior medullary valum,tela
choroidae(fold of piamatter)&inferior cerebellar peduncle.
3-Lateral walls of the 4
th
ventricle: are formed by
superior&inferiorcerebellar peduncles.
Fourth ventricle

9. Cranial nerves
3,4: emerge from the surface of
midbrain.
5: from pons.
6,7,8: emerge at the junction of
pons& medulla.
9,10,11,12: emerge from the
surface of medulla.
Dr Iman Nabil 9

10. Respiratory areas in brain stem
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11. Cranial nerves nuclei
1-Nuclei of III&IV: in the midbrain.
2-Nuclei of V, VI, VII& part of VIII: in pons.
3-Nuclei of remaining part of VIII, IX, X, XI&
XII: in the medulla.
•Note:
Some of the cranial nerve nuclei extend
along more than one level of the brain
stem.
Some of these nuclei contribute fibersfor
more than one nerve.
Some of the cranial nerves consist of
fibersarising from more than one
nucleus.
Dr Iman Nabil 11

12. Which cranial nerve emerges from the surface
of the pons?
1-Abducentnerve.
2-Facial nerve.
3-Trigeminal nerve.
4-Oculomotornerve.
Dr Iman Nabil 12

13. Which cranial nerve emerges from the surface
of the pons?
1-Abducentnerve.
2-Facial nerve.
3-Trigeminal nerve.
4-Oculomotornerve.
Dr Iman Nabil 13