Brain stem

1. MEDULLA OBLONGATA
Dr. Aamir
DPT(AIMC), M.Phil.
Lecturer, Quaid-e-Azam Educational Complex, Sahiwal

2. Medulla
oblongata
It connects with the pons
superiorly and spinal cord
inferiorly.
It is conical in shape.
It is broad superiorly and
narrow inferiorly.

5. Cavityof
Medulla
oblongata
The fluid filled cavity at
the lower end of medulla
oblongata is central
canal.
While at the upper end,
the cavity expands to
form fourth ventricle.

8. Anterior aspect

12. Anterior
medianfissure
On the anterior
surface lies anterior
median fissure.
It is continuous with
anterior median
fissure of spinal cord.

13. Pyramids
On each side of median
fissure a swelling is
present called as
pyramids.

15. How Pyramids
areformed?
The pyramids are composed
of bundles of axon fibers
The pyramids taper
inferiorly.
Inferiorly majority of these
fibers cross to opposite side
to form decussation of
pyramids.

17. olives
Posterolateral to
pyramids lie oval
elevations, which are
named as olives.
This is produced by
underlying olivary
nuclei particularly
inferior olivary nucleus.

18. Inferior
cerebellar
peduncles
In the upper part of
medulla,
Posterior to olive lies
connection between
medulla and cerebellum
called as inferior
cerebellar peduncles.

20. Posterior aspect

22. Posterior
mediansulcus
On the posterior
aspect of medulla
oblongata lies
posterior median
sulcus.

25. Tubercleson
posterioraspect
On the posterior
aspect two
tubercles are there,
1.Gracile Tubercle
2.Cuneate Tubercle

26. Internal structure of
medulla oblongata

27. Internal
structureof
medulla
 Regarding internal structure of medulla
oblongata, 4 things will be discussed in the
whole internal structure of medulla,
1. Ascending systems through medulla with
nuclei.
2. Descending pathways through medulla
3. Cerebellar connections through medulla
4. Cranial nerves and their nuclei through
medulla
 Cranial nerves will IX, X, XI and XII
 Trigeminal system (CN. V)

31. Levelsofstudy of
internal structure
ofMedulla
oblongata
Regarding the study
of internal structure
of medulla oblongata,
transverse sections of
medulla oblongata at
4 different levels are
used.

32. Transverse section
ofmedulla at4
levels
From inferior to superior
1. At the level of decussation of
pyramids
2. At the level of decussation of
lemnisci
3. At the level of inferior
cerebellar peduncles or olives
4. At the level just inferior to
pons

35. Functions
It is a pathway for ascending
and descending tracts.
House of vital centers.
Respiratory centers
Vasomotor centers and Cardiac
Centers
Vomiting Center (Chemo trigger
Zone)

44. Functions
Cranial Nerve Nuclei
 12th Cranial Nerve Nuclei for
tongue muscles (CN XII)
 Eleventh Cranial Nerve Nuclei for
shoulder movements (CN XI)
 Tenth Cranial Nerve Nuclei for
important Visceras viz Heart,
lungs etc. (CN X)
 Eight Cranial Nerve control
auditory function by cochlear
division, vestibular nerve nuclei
control balance. (CN VIII)

45. Thank You