Anatomy of the brain

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 Adul t brain weighs about three pounds Has 4 major rejoins 1: CEREBRUM 2: DIENCEP HALON 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 Individuals who have problems with their basal nuclei are often unable to walk normally or carryout other voluntary movements.

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.