Stalk LikeStalk Like.. ConnectsConnects::

Narrow Spinal Cord with the Narrow Spinal Cord with the Expanded Fore BrainExpanded Fore Brain..

OccupiesOccupies:: Posterior Cranial FossaPosterior Cranial Fossa..

Lies AgainstLies Against:: Basilar part of Occipital Basilar part of Occipital

BoneBone..Largely Covered by:Largely Covered by:

CerebellumCerebellum..

MEDULLAOBLONGATA

PONS

MIDBRAIN

BULBBULB..Entering FibersEntering Fibers : :

Cortico BulbarCortico Bulbar..Syndromes AssociatedSyndromes Associated::

Pseudo Bulbar PalsyPseudo Bulbar Palsy.. Bulbar PalsyBulbar Palsy..

((11)) A conduit forA conduit for:: Ascending and Descending Ascending and Descending

tracts between the Spinal tracts between the Spinal Cord and the Higher Centers Cord and the Higher Centers in the Forebrainin the Forebrain..

((22 ) )ContainsContains:: A. A. Cranial Nerve Nuclei (111-Cranial Nerve Nuclei (111-

x11)x11)..B.B. Reflex Centers for Reflex Centers for

Respiratory and Respiratory and Cardiovascular systemsCardiovascular systems..

((33 ) )Controls overControls over:: Level of ConsciousnessLevel of Consciousness

The Ventral Median The Ventral Median FissureFissure

Divides it into Two Divides it into Two HalvesHalves..

Each Half Presented Each Half Presented the followingthe following: :

A Longitudinal Elevation A Longitudinal Elevation along the side of the along the side of the fissurefissure..

The pyramids are The pyramids are composed ofcomposed of::

Bundles of Nerve FibersBundles of Nerve Fibers (Corticospinal)(Corticospinal)..

They originate from They originate from Large Nerve Cells in the Large Nerve Cells in the Motor Cerebral CortexMotor Cerebral Cortex..

The Pyramids Taper The Pyramids Taper InferiorlyInferiorly..

The The MajorityMajority of the of the Descending Fibers Descending Fibers (75-90%) (75-90%) Cross OverCross Over to the opposite side.to the opposite side. They formThey form

Decussation of the Decussation of the PyramidsPyramids..

It partially obscures It partially obscures the ventral fissurethe ventral fissure..

Oval ElevationOval Elevation..

Lateral to the Upper Part Lateral to the Upper Part of the Pyramidof the Pyramid..

Produced byProduced by

The underlying The underlying InferiorInferior Olivary NucleusOlivary Nucleus

It is Important in the It is Important in the Control of MovementControl of Movement..

11 . .Hypoglossal (12Hypoglossal (12TH)TH) nervenerve::

Between the Pyramid Between the Pyramid and Oliveand Olive..

22.. GlossopharyngealGlossopharyngeal,, VagusVagus and and Cranial partCranial part of Acessoryof Acessory (9, 10 (9, 10 and11and11TH)TH) nerves nerves: :

Between the Olive and Between the Olive and the Inferior Cerebellar the Inferior Cerebellar PedunclePeduncle..

The Anterior surface is The Anterior surface is Convex from side to sideConvex from side to side..

It showsIt shows:: Basilar SulcusBasilar Sulcus: :

A Median Groove which A Median Groove which lodges the lodges the Basilar ArteryBasilar Artery..

Many Transverse Many Transverse Pontocerebellar FibersPontocerebellar Fibers . .

They are collected Laterally They are collected Laterally to form the to form the Middle Middle Cerebellar PedunclesCerebellar Peduncles..

11 . .Trigeminal (5Trigeminal (5thth) nerve) nerve:: Attached to the side of Attached to the side of

the Pons near its upper the Pons near its upper borderborder..

It has Two RootsIt has Two Roots::Large SensoryLarge Sensory . .

Small MotorSmall Motor.. Motor root is Antero Motor root is Antero

Medial to the Sensory Medial to the Sensory rootroot..

22 . .Abducent (6Abducent (6thth) nerve) nerve::Between the Lower Between the Lower

border of the Pons and border of the Pons and the Pyramidthe Pyramid..

33 . .Facial (7Facial (7thth) nerve) nerve: : Between the Lower Between the Lower

border of the Pons and border of the Pons and the Inferior Cerebellar the Inferior Cerebellar PedunclePeduncle..

44 . .Vestibulo cochlear (8Vestibulo cochlear (8thth) ) nervenerve: :

Lateral to the FacialLateral to the Facial . . The vestibular nerve is The vestibular nerve is

anterior to the cochlearanterior to the cochlear..

It is theIt is the: : Massive Basis Massive Basis

PedunculiPedunculi (Crura (Crura Cerebri)Cerebri)..

The Crura are made byThe Crura are made by:: Corticobulbar.Corticobulbar.

Corticospinal FibersCorticospinal Fibers..

Separates the Cerebral Separates the Cerebral PedunclesPeduncles..

BoundariesBoundaries:: InferiorlyInferiorly: :

PonsPons..AnteriorlyAnteriorly: :

Optic ChiasmaOptic Chiasma.. LaterallyLaterally::

Optic TractsOptic Tracts. . PosterolaterallyPosterolaterally::

Cerebral PedunclesCerebral Peduncles..

Oculo motor (3Oculo motor (3rdrd) ) nervenerve: :

At the medial side of At the medial side of the cerebral the cerebral pedunclepeduncle..

Closed (Lower) MedullaClosed (Lower) Medulla It is the Continuation of It is the Continuation of the Posterior Surface of the Posterior Surface of the Spinal Cordthe Spinal Cord..

Posterior MedianPosterior Median Sulcus Sulcus divides it into two divides it into two halveshalves..

Gracile TractGracile Tract:: A Longitudinal Column on both A Longitudinal Column on both

sides of the Median Sulcussides of the Median Sulcus.. SuperiorlySuperiorly:: It expandsIt expands..

It ends in theIt ends in the GracileGracile TubercleTubercle (produced by the underlying (produced by the underlying ((Gracile NucleusGracile Nucleus))..

Cunate Tract and TubercleCunate Tract and Tubercle: : Lateral to the Gracile Tract Lateral to the Gracile Tract

and Tubercle respectivelyand Tubercle respectively..

Forms the Lower 1/3 of Forms the Lower 1/3 of the the Floor of the Fourth Floor of the Fourth VentricleVentricle..

Divided by the Median Divided by the Median Sulcus into two halvesSulcus into two halves..

Has an inverted (V) Has an inverted (V) Shaped Depression Shaped Depression (Inferior Fovea)(Inferior Fovea)..

The Fovea separates:The Fovea separates: Motor nucleiMotor nuclei (Medial) (Medial) from from Sensory nucleiSensory nuclei (Lateral) (Lateral)..

MedialMedial: : Hypoglossal NucleusHypoglossal Nucleus..

LateralLateral: : Vestibular NucleusVestibular Nucleus..

At the FoveaAt the Fovea: : Nuclear Complex Nuclear Complex

(Glossopharyngeal (Glossopharyngeal and Vagus nerves)and Vagus nerves)..

The Fovea represents The Fovea represents the Sulcus Limitans of the Sulcus Limitans of the Spinal Cordthe Spinal Cord . .

Forms the Upper 2/3 of the Forms the Upper 2/3 of the Floor of the 4Floor of the 4thth Ventricle Ventricle..

Hidden by the CerebellumHidden by the Cerebellum..Widest at the Widest at the

PontomedullaryPontomedullary junction junction..Lateral Aperture Lateral Aperture (Foramen of (Foramen of

Luschka)Luschka):: Allows passage of CSF from Allows passage of CSF from

the 4the 4THTH ventricle to the ventricle to the Subarachnoid space around Subarachnoid space around the brainthe brain..

Divided into Symmetrical Halves Divided into Symmetrical Halves by the by the Median SulcusMedian Sulcus..

Medial EminenceMedial Eminence:: An Elongated Elevation Lateral An Elongated Elevation Lateral

to the Sulcusto the Sulcus..Facial ColliculusFacial Colliculus::

The Inferior Expanded end of The Inferior Expanded end of the Eminencethe Eminence . .

Produced by the fibers of the Produced by the fibers of the Facial NerveFacial Nerve winding around the winding around the Abducent NucleusAbducent Nucleus..

Vestibular AreaVestibular AreaLateral to the Medial Lateral to the Medial

EminenceEminence.. Produced by the Produced by the

underlying underlying Vestibular NucleiVestibular Nuclei..

Corpora QuadregiminaCorpora Quadregimina Four Rounded Colliculi Four Rounded Colliculi Divided into Superior Divided into Superior and Inferior Pairsand Inferior Pairs..

Superior Colliculi:Superior Colliculi: Centers of Visual Centers of Visual ReflexesReflexes..

Inferior Colliculi:Inferior Colliculi: Lower Auditory Lower Auditory CentersCenters..

The Cerebral The Cerebral AqueductAqueduct traverses traverses through the length of through the length of the mid brainthe mid brain..

Trochlear NerveTrochlear Nerve It is the It is the OnlyOnly cranial cranial

nerve that can be nerve that can be identified in the dorsal identified in the dorsal aspect of brain stemaspect of brain stem..

It emerges in the It emerges in the midlinemidline..

Caudal to the Caudal to the Inferior Inferior ColliculsColliculs..

SuperiorSuperior..MiddleMiddle..

Inferior Inferior PedunclesPeduncles..Connect Cerebellum Connect Cerebellum

toto: : Mid brainMid brain..

PonsPons . .MedullaMedulla..

MiddleMiddle. . InferiorInferior Cerebellar Cerebellar

PedunclesPeduncles..OliveOlive..

PyramidPyramid..Attached Cranial Attached Cranial

NervesNerves..