lecture on Anatomy of Brain

1. Anatomy Of The Brain
Lecture Presented by: Dr. Saiqua Lashari

2. Two fist full of pinkish gray tissue
Wrinkled like wall nut
And with the texture of cold oat meal
Adult brain weighs about three pounds
Has 4 major rejoins
1: CEREBRUM
2: DIENCEPHALON
3: BRAIN STEM
4: CEREBELLUM

3. The Brain Has Three Main Anatomical Divisions:
 Forebrain (cerebrum)
 Midbrain
 Hindbrain (pons, medulla and cerebellum)

4. Three Functional
Divisions:Regulations
Cerebrum Cerebellum Brainstem
Sensory muscle coordination vital regulations
and motor and balance heart, lungs, GI

5. THE CEREBRUM (CEREBRAL
HEMISPHERES)
 Paired cerebral hemispheres collectively are called CEREBRUM.
 Most superior and larger part
 Entire surface of cerebrum exhibit elevated ridges i.e Gyri(ji’re)
 Separated by shallow grooves (less deeper) called sulci ( sul’ki)
 There are also few deep grooves termed as Fissures.
 Fissure separate large regions of the brain

6. Hemispheres
 The Brain has two sides:
 Left hemisphere
 Right hemisphere
 Left brain controls the right side of the body
 Right brain controls the left side of the body
 Left handed people are the only ones in their “right mind”!

7. Fissures and sulci
 Longitudinal fissure:
 This is a single deep fissure that
separates two cerebral hemispheres.
 CENTRAL FISSURE(SULCUS): Separates
frontal lobe from parietal lobe
 LATERAL FISSURE(SULCUS ): It borders
temporal lobe from rest of the
cerebral hemisphere laterally.

8. LOBES OF CEREBRAL HEMISPHERE
 FRONTAL LOBE: primary motor area> corticospinal tract or
pyramidal tract> this tract leads to spinal cord.
 PARIETAL LOBE : Somatic sensory area is located posterior
to central sulcus. Recognize: pain, coldness or light touch.
Sensory pathways are crossed pathways.
 OCCIPITAL LOBE: Visual area
 TEMPORAL LOBE: Auditory area

9. BROCA’S AREA
 AT the base of precentral gyrus
 Area involved in our ability of
speaking
Damage to this area ,which is located in
only one cerebral hemisphere (usually
left) causes inability to say words
properly.
You know what to say but you cant
vocalize the words.

10. Speech Area ( wernike’s area)
 At the junction of the temporal,parietal and occipital lobes.
 Sound out words properly.
 This area is also in one cerebral hemisphere i.e left.
 Gray matter of hemispheres: cell bodies of neurons: making cortex of
hemispheres i.e cerebral cortex
 White matter : fiber tracts ( bundles of nerve fibers) carrying impulse to
and from cortex

11. Corpus callosum
 Very large fiber tract connect both hemispheres.
 Communication between two hemispheres

12. BASAL GANGLIA OR BASAL NUCLEI
BASAL GANGLIA OR BASAL NUCLEI
 Islands of gray matter burried deep within the
white matter of cerebral hemisphere.
 Involved in regulation of voluntary motor
activities by modifying instructions sent to the
skeletal muscles by primary motor cortex.

13. ALZHEIMERS DISEASE
 Associated with shortage of acetylcholine and with structural changes in the
brain particularly in areas involved with cognition and memory .
 The gyri shrink , and brain atrophies .

14. HUNTINGTONS & PARKINSONS DISEASE

15. Diencephalon ( Interbrain)
 Sits atop the brain stem and
is enclosed by the cerebral
hemispheres.
 Major structures of the
diencephalon are the
thalamus , hypothalamus and
epithalamus (pineal
gland=melatonin , circadian
rhythm + Habenular nucleus).

16. Thalamus
 Encloses the
shallow third
ventricle of the
brain.
 Relay station of
the sensory
impulses passing
upward to the
sensory cortex.

17. ANATOMY OF THE THALAMUS

18. Ventricle system of Brain

19. NUCLEI OF THALAMUS

20. The Hypothalamus
 Below the thalamus ( under the thalamus)
 Makes up the floor of the Diencephalon .
 It is important autonomic nervous system center because it plays a role in
regulation of body temperature ,water balance and metabolism.
 The hypothalamus is also the center for many drives and emotions, and as
such important part of the limbic system or emotional visceral brain.
 For example: thirst, appetite, sex, pain and pleasure centers are in the
hypothalamus.
 Also regulates pituitary gland and also produces two hormones of its own.
 Pituitary gland hangs from the anterior floor of the hypothalamus by a slender
stalk.
 The mammillary bodies , reflex centers involved in olfaction ( the sense of
smell), buldge from the floor of the hypothalamus posterior to the pituitary
gland.

21. CORELATIONS OF HYPOTHALAMUS

22. The Epithalamus
 Forms roof of the third ventricle
 Consists of pineal body and choroid plexus of the third ventricle
 Choroid plexus is a plexus ( network of nerves or vessels) of cells with in each
ventricle, form the cerebrospinal fluid.
 Ependymal cells form plexus and produce CSF inside the ventricles .
 Habenular nucleus is also present at the epithalamus( regulator of CNS
neurotransmitters) i.e monoamines.

23. Brain Stem
 Brain stem is about the
size of a thumb in
diameter and
approximately 3 inches
( 7.5 cm ) long
 Consists of Mid brain,
Pons and medulla
oblongata
 Provides path for
ascending and
descending tracts
 Nuclei for cranial
nerves

24. MID BRAIN
 It is a narrow part of the brain
 Passes through the tentorial notch
 Connects forebrain to Hindbrain
 Consists of two lateral halves >>>> CEREBRAL PEDUNCLES
 Each cerebral peduncle is divided into anterior part , >>>>>Crus
cereberi
 And posterior part tegmentum
 Divided by a pigmented band of gray mater , the substantia nigra
 CEREBRAL AQUEDUCT> Narrow cavity , connects third ventricle
to fourth ventricle
 Tectum lies posterior to aqueduct has four small surface
swellings
 They are called two superior colliculi and two inferior colliculi

25. Cross section view of the Mid Brain

26. Posterior view of Mid Brain

27. HIND BRAIN
 THE PONS < bridge>
 Situated on the anterior surface of the cerebellum
 below the midbrain
 Above the medulla oblongata
 Composed of nerve fibers which connect two halves of cerebellum
 Also contains ascending and descending fibers connecting the forebrain , mid
brain and spinal cord.
 Some nerve cells function as relay stations and others form cranial nerve
nuclei.

28. THE MEDULLA OBLONGATA
 Conical in shape
 Median fissure at the anterior surface of medulla
 On each side of this fissure there is a swelling called pyramid
 Pyramids consists descendings fibers that originate from precentral gyrus of
the cerebral cortex.
 Descending fibers of pyramids at the end cross over to opposite sides making
decussation of the pyramids
 Posterior to pyramids are olive , which are the oval elevations of produced by
the olivary nuclei
 Behind the olives are cerebellar peduncles
 On the posterior surface of the inferior part of medulla oblongata are the
gracile and cuneate tubercles
 NUCLEUS GRACILIS + NUCLEUS CUNEATUS

29. CRANIAL NERVES

30. CRANIAL NERVES EMERGING FROM BRAIN
STEM

31. THE CEREBELLUM
 Cerebellum lies with in the posterior cranial fossa beneath the tentorium
cerebelli.
 Lies posterior to pons and medulla
 Consists of two hemispheres connected by median portion vermis
 Surface layer of medulla is called cortex composed of gray matter.
 cerebellar cortex has folds called folia, separated by transverse fissures.
 Dentate nuclei is the largest of gray matter found in between white matter of
cerebellum.