The Brain & The Spinal CordThe Brain & The Spinal CordI- The brain:I- The brain:

1- The Meninges:1- The Meninges: Dura Matter Dura Matter Arachinoid MatterArachinoid Matter Pia MatterPia Matter

2- The forebrain2- The forebrainCerebrumCerebrumDiencephalonDiencephalon

4- The Hind Brain4- The Hind BrainPonesPonesMedullaMedullaCerebellumCerebellum

II- The spinal cordII- The spinal cord

3- Midbrain3- Midbrain

MidbrainMidbrain– Connect the diencephalon Connect the diencephalon

to the pons and lies in the to the pons and lies in the posterior cranial fossa.posterior cranial fossa.

– Consist of right and left Consist of right and left halves each forming the halves each forming the cerebral peduncle, cerebral peduncle,

– Divided into ventral and Divided into ventral and dorsal part with a narrow dorsal part with a narrow cavity running through the cavity running through the dorsal part, the dorsal part, the aqueductaqueduct

The Brain & The Spinal CordThe Brain & The Spinal Cord

I- The brain:I- The brain:1- The Meninges:1- The Meninges:

Dura Matter Dura Matter Arachinoid MatterArachinoid MatterPia MatterPia Matter

2- The forebrain2- The forebrainCerebrumCerebrumDiencephalonDiencephalon

3- Midbrain3- Midbrain

II_ The spinal cordII_ The spinal cord

4- The Hind Brain4- The Hind BrainPonesPonesMedullaMedullaCerebellumCerebellum

HindbrainHindbrain

• The Pons:The Pons:• Lie on the anterior surface of the cerebellum Lie on the anterior surface of the cerebellum

below the midbrain and above the medulla.below the midbrain and above the medulla.– FibresFibres

• Composed mainly of:Composed mainly of:– nerve fibres connecting the two halves of the nerve fibres connecting the two halves of the

cerebellumcerebellum– ascending and descending fibres connecting the ascending and descending fibres connecting the

forebrain, midbrain and spinal cordforebrain, midbrain and spinal cord• The sensory and motor roots of the 5The sensory and motor roots of the 5thth cranial cranial

nervenerve

HindbrainHindbrain

• Cells:Cells:– Some serve as relay stations while others Some serve as relay stations while others

form cranial nerve nuclei.form cranial nerve nuclei.• Pontine nuclei, relay station in the ventral surfacePontine nuclei, relay station in the ventral surface• 55thth – 8 – 8thth cranial nerves nuclei, dorsal part cranial nerves nuclei, dorsal part• Trigeminal, abducent, facial, vestibulotrochlearTrigeminal, abducent, facial, vestibulotrochlear• Motor nucleus of the 5Motor nucleus of the 5thth nerve, upper pons nerve, upper pons• Sensory nucleus of the 5Sensory nucleus of the 5thth nerve lateral to the motor nerve lateral to the motor• Superior salivary nuclei (Parasympathetic), fibres join Superior salivary nuclei (Parasympathetic), fibres join

nervus intermedius nervus intermedius • Inferior salivary nucleus, fibres join glossopharyngeal N Inferior salivary nucleus, fibres join glossopharyngeal N

Pons Pons

HindbrainHindbrain

• Medulla oblongata: oblongata:– Conical in shape and lie vertically connecting the Conical in shape and lie vertically connecting the

Pons to the spinal cord, passes through foramen Pons to the spinal cord, passes through foramen magnummagnum

• PyramidPyramid– a deep groove in the midline on the ventral surface, a deep groove in the midline on the ventral surface,

contain the corticospinal fibres.contain the corticospinal fibres.• OliveOlive

– convex structure, lateral to the pyramid, contain the convex structure, lateral to the pyramid, contain the inferior salivary nucleusinferior salivary nucleus

• Inferior cerebellar peduncleInferior cerebellar peduncle– behind the olive, connect the medulla to the cerebellum behind the olive, connect the medulla to the cerebellum

Medulla

HindbrainHindbrain

• Structures:Structures:– Nucleus:

• 9th –12th cranial nerves– Reticular formation: Reticular formation:

• is an irregular mass of cell and fibres that extend up into is an irregular mass of cell and fibres that extend up into the pons and down into the spinal cordthe pons and down into the spinal cord

– The cells:The cells:• Cardiac and respiratory centers Cardiac and respiratory centers • vomiting centervomiting center• Chemoreceptor trigger zone communicate with the cardiac Chemoreceptor trigger zone communicate with the cardiac

and respiratory centers.and respiratory centers.

Medulla

HindbrainHindbrain

• Cerebellum:Cerebellum:– Occupy the posterior cranial fossa posterior to Occupy the posterior cranial fossa posterior to

the pons and medullathe pons and medulla– Consist of two hemisphere united in the Consist of two hemisphere united in the

midline by the vermis.midline by the vermis.• Each hemisphere consist of a small anterior and a Each hemisphere consist of a small anterior and a

large posterior lobe separated by shallow groove, large posterior lobe separated by shallow groove, primary fissureprimary fissure

– Connected to the midbrain, pons and medulla Connected to the midbrain, pons and medulla by the superior, middle and inferior cerebellar by the superior, middle and inferior cerebellar pedunclespeduncles

•Cerebellum:

HindbrainHindbrain

• Structure:– Surface layer is the cortex of grey cells, with Surface layer is the cortex of grey cells, with

white matter internal.white matter internal.– The cortex is thrown into folds or folia, The cortex is thrown into folds or folia,

separated by transverse fissuresseparated by transverse fissures– The dentate nucleus is a mass of grey matterThe dentate nucleus is a mass of grey matter

• Control of muscle tone and co-ordination of Control of muscle tone and co-ordination of muscle movement on the same side muscle movement on the same side

•Cerebellum:

HindbrainHindbrain• The fourth ventricle:The fourth ventricle:

– Is the cavity of the hindbrain and bounded in front Is the cavity of the hindbrain and bounded in front by the pons and medulla and from behind by the by the pons and medulla and from behind by the cerebellum.cerebellum.

– It is connected above to the third ventricle by the It is connected above to the third ventricle by the cerebral aqueduct, and below it is continuous with cerebral aqueduct, and below it is continuous with central canal of the spinal cord.central canal of the spinal cord.

– It communicate with subarachnoid space by three It communicate with subarachnoid space by three openings in the lower part of the roof, a median and openings in the lower part of the roof, a median and two lateral openings.two lateral openings.

The Brain & The Spinal CordThe Brain & The Spinal CordI- The brain:I- The brain:

1- The Meninges:1- The Meninges:Dura Matter Dura Matter Arachinoid MatterArachinoid MatterPia MatterPia Matter

2- The forebrain2- The forebrainCerebrumCerebrumDiencephalonDiencephalon

3- Midbrain3- Midbrain4- The Hind Brain4- The Hind Brain

PonesPonesMedullaMedullaCerebellumCerebellum

•II- The spinal cordII- The spinal cord

The spinal cordThe spinal cord

• Is cylindrical in shape, begins at the foramen Is cylindrical in shape, begins at the foramen magnum and terminate inferiorly at the lower magnum and terminate inferiorly at the lower border of the 1border of the 1stst lumber vertebra. lumber vertebra.– Surrounded by the three meninges, Dura, Surrounded by the three meninges, Dura,

Arachnoid and Pia matter.Arachnoid and Pia matter.– CSF fills the Subarachnoid space, add protection.CSF fills the Subarachnoid space, add protection.– 31 pairs of spinal nerves are attached to the spinal 31 pairs of spinal nerves are attached to the spinal

cord by an anterior (motor) and posteriorcord by an anterior (motor) and posterior (sensory) roots (sensory) roots

The spinal cordThe spinal cord(cont)(cont)

• Structure::– Consist of a central mass of grey matter Consist of a central mass of grey matter

surrounding a central canal, a downward surrounding a central canal, a downward continuation of the fourth ventricle, enclosed in a continuation of the fourth ventricle, enclosed in a cylindrical mass of white matter.cylindrical mass of white matter.

– The anterior fissure and the posterior septum The anterior fissure and the posterior septum divide the cord into two halves divide the cord into two halves

– Both the grey & white matter are divided into Both the grey & white matter are divided into anterior, lateral and posterior horns & columns of anterior, lateral and posterior horns & columns of cells and fibrescells and fibres..

The spinal cordThe spinal cord(cont)(cont)

– Grey matter: • H-shaped, enlarged in the cervical and H-shaped, enlarged in the cervical and

lumbosacral region due to increase in the lumbosacral region due to increase in the number of the cells in the anterior horn rootnumber of the cells in the anterior horn root

– White matter.• contain three types of fibres, ascending, contain three types of fibres, ascending,

descending and intersegmental descending and intersegmental