The document provides an overview of the structure and function of the human brain. It discusses the major divisions and parts of the brain including the cerebrum, basal ganglia, thalamus, hypothalamus, brain stem, limbic system, reticular formation, and cerebellum. For each area, it describes the location, functions, clinical relevance, blood supply, and connections. The summary highlights the key points that the brain controls functions like memory, intelligence, emotions, movement, sensation, homeostasis, and autonomic functions. It is made up of gray and white matter containing neurons, axons and dendrites. The three major divisions are the forebrain, midbrain, and hindbrain.

1. BRAIN
Guide- Dr Nimish (Reader)
Department of Oral and Maxillofacial
surgery

2.  Introduction →Central Nervous system -Division and classification
 Development of Brain
 Parts of brain
 Cerebrum→ parts and functions, clinical aspects and vasculature
 Basal Ganglia→ parts, functions and clinical aspects
 Thalamus,hypothalamus→ parts ,functions and clinical aspects
 Brain stem→ parts, functions and clincal aspects
 Limbic System
 Reticular formation
 Cerebellum

3. • BRAIN- learning, memory, intelligence and emotions.
• Weight 1500 grams(2% body weight)
• Average dimensions 167 mm long, 93 mm height and 140 mm wide (approx)
• 75%- water connected by trillions of synapses
• contains- 100 billion neurons (approx) “Grey matter”
• axons and dendrites (in billions) “White matter”
INTRODUCTION

5. BRAIN AND SPINAL CORD SENSORY INFORMATIONS
MOTOR ACTIONS
INTEGRATION &
COORDINATION
AFFERENS
EFFERENCE
CENTRAL NERVOUS SYSTEM
SOMATIC
muscles,glands,blood vessels &
heart
control of skeletal muscles
heart,smooth muscle of organs,
glands & blood vessels.

6. Development of Brain
Predecessor- brain and spinal cord → neural tube.
Split into 3 major layers: the hindbrain, the midbrain, and the forebrain.

8. Dural venous Sinuses

9. Primary
vesicle
Primary Division Subdivision Adult Structure Neural
canal
Remnant
Forebrain Prosencephalon Telencephalon • Cerebrum
• Basal ganglia
• Hippocampus
Lateral
ventricle
Diencephalon • Thalamus
• Hypothalamus
• Pineal body
• Infundibulum
Third
ventricle
Midbrain Mesencephalon Mesencephalon • Crus cerebri
• Tectum
• Tegmentum
Cerebral
Aqueduct
Hindbrain Rhombencephalon Metencephalon • Pons
• Cerebellum
Fourth
V
entricle
Myelencephalon • Medulla oblongata

10. Cerebrum
2 cerebral hemispheres
(incompletely separated-longitudinal fissure)
(connected-in median plane-corpus callosum)
Each hemisphere contains a cavity called the
lateral ventricle.

11. Cerebral cortex folded into gyri separated by sulci.
Increases surface area/allows more packing of
neurons/increases brains ability
The total area of the cortex is estimated to
be more than 2000 cm2. (2/3rd hidden within
sulci)

14. FRONTAL LOBE
4. Movement control
5. Speech and language
1. Prospective memory
2. Decision making
3. Personality
PARIETAL LOBE
1. Interpreting simple somatosensory signals 2. Learning 3. Language
4. Spatial recognition 5. Motor planning action
6. Sensorimotor planning 7. Stereognosis
TEMPORAL LOBE
1. Auditory processing and perception
3. Language recognition
2. Object perception and recognition
4. Declarative memory
OCCIPITAL LOBE
1. Visual processing and interpretation

15. MOTOR AREA
• 1︒ motor area →identified on the basis of elicitation of motor responses at a low threshold of
electric stimulation →contraction of skeletal musculature.
• gives origin corticospinal ＆ corticonuclearfibres.

16. SENSORY AREA
• Electrical activity can be recorded
appropriate sensory stimulus
particular part of the body.

17. ASSOCIATION AREA
• Direct sensory or motor responses are notelicited
• integrate and analyse the responses from various sources.
AA are known to have motor or sensory functions.
motor and sensory functions also overlap in the same region of cortex.
motor function predominant sensory function is predominant
(motor-sensory) (sensori-motor)

18. Broadman area
German anatomist Korbinian Brodmann
Cytoarchitectural organization of neurons
Nissl method of cell staining

20. • Electrical stimulation primary motor area elicits contraction of muscles(contralateral)
• Although cortical control of musculature is mainly contralateral, there is significant ipsilateral
control of most of the muscles of the head and axial muscles of the body.
A cortical homunculus
↓
distorted representation of the human body, based
on a neurological "map" of the areas and
proportions of the human brain dedicated to
processing motor functions, or sensory functions,
for different parts of the body.

21. Cortical area for a particular body part
Determined by the functional importance/need for sensitivity/
intricacy of the movements
Area for the face, larynx,lips,hand(thumb)
is disproportionately large
Cortical Homunculus
• The contralateral half of the body is represented as upside down,except the
face.
• Pharyngeal region ＆ tongue
Most ventral and lower part of precentral gyrus
• Leg,foot and perineum medial surface of hemisphere Paracentral
lobule.

22. Vasculature of Cerebrum
The blood supply to the cerebrum
↓
3 distinct paired arterial branches
Anterior cerebralArtery
Middle cerebralArtery
Posterior cerebral artery
1. Anterior Cerebral Arteries
2. Middle cerebral arteries
3. Posterior Cerebral Arteries

23. The cerebral veins empty → dural venous sinuses.
• superficial system → superior sagittal sinus
• deep system → transverse, straight and sigmoid sinuses.

24. Circle of Willis →interpeduncular fossa→ base of the brain.

25. 1. Corpus Striatum
a. Caudate Nucleus
b. Lentiform Nucleus
Parts of basal ganglia
Globus pallidus
Putamen
2. Amygdaloid Body
3. Claustrum

28. Functions of basal ganglia
control muscular movement -influencing cerebral cortex (no direct control of descending
pathways)
• Influence skill cortical motor activities like :-
- Routine behaviour or habit
- Cognition
- Passing football
- Drawing a diagram
- Writing letters of the alphabet
• Exerts inhibitory influence on a number of motor system.
• Help prepare for the movement.

29. Disorders associated with basal ganglia
1. Hypokinetic disorder:
- Parkinson’s disease
2. Hyperkinetic disorders:
Disorder Area involved
1. Chorea Caudate nucleus
• Huntington’s
• Sydenham’s
• Wilson’s disease
2.Athetosis Putamen
3. Ballismus (hemi) Subthalamic nucleus
4. Dystonia Putamen

31. Parkinson’s disease
Degenerative changes in globus pallidus & substansia nigra
with marked reduction of dopamin.
bradykinesia, rigidity, tremor ＆loss of postural reflexes.
Classical Triad:
1. Tremor (Resting tremor)
2. Rigidity (increased muscle tone)
3. Bradykinesia (Slowness of movement)

32. THALAMUS
EPITHALAMUS

33. 1. Thalamus
“inner room” (Greek)
deep in the brain /top of the brainstem.
Gateway to the cerebral cortex,
All sensory inputs pass through it to
the higher levels (cerebral cortex)
Location- On each side of 3rd ventricle

34. Functions of Thalamus
• Sensory relay centre.
• Crude centre for perception of sensation.
• Arousal & alertness reaction.
• Language.
• Emotional aspect of behaviour.
• Sexual sensation.
• Reflex activity centre
• Integration of
Sensory impulses & Motor functions.
Visceral & somatic function.

35. Clinical relevance
Thalamic Hand (thalamic lesions)
The contralateral hand - abnormal posture
wrist pronated ＆flexed,metacarpophalangeal joints flexed ＆ interphalangeal joints extended.
fingers can be moved actively, but movements are slow,altered muscle tone in the different
muscle groups.

36. 2. Hypothalamus
Situated under the thalamus atop the brainstem.
Though small-controls many critical bodily
functions:
• Controls autonomic nervous system
• Regulates body temperature
• Regulates food intake
HYPOTHALAMUS

37. Functions of Hypothalamus
• Regulates water balance and thirst
• Controls sleep-wake cycles
• Functionally, the hypothalamus is part of the limbic system (which is involved in
memories and emotions)
painful memory →↑blood pressure, a good memory → ↓blood pressure.
It is the Center for emotional response and behavior
hypothalamus synthesizes and secretes→ hormones, → ＋ / － secretion of pituitary
hormones & thus Controls endocrine system.

38. The brainstem → most primitive part of the brain
controls basic functions of life:
• breathing,
• heart rate,
• swallowing,
• reflexes to sight or sound,
• sweating,
• blood pressure,
• sleep, and balance.

39. • It connects the spinal cord →cerebrum.
• The ascending and descending tracts pass through the components of the
brainstem.
• Medulla oblongata → respiratory and vasomotor centres.
• Midbrain →nuclei of oculomotor and trochlear nerves.
• Pons → nuclei of trigeminal, abducent, facial and statoacoustic nerves.
• Medulla → the nuclei of glossopharyngeal, vagus, accessory and hypoglossal
nerves.
The brainstem divided 3 major sections
1. Midbrain
2. Pons
3. Medulla oblongata

42. Further down the brainstem
relays sensory information between the
cerebellum (for balance) and cerebrum
(conscious awareness).
like medulla it has sensory and motor tracts.
contains nuclei →deals with respiration,
swallowing,bladder control,
hearing, equillibrium,eyeball movements and
facial expression.

43. base of the brainstem
centers- cardiac, respiratory,vomiting ＆vasomotor centers.
It controls the nerves that effect the heart rate, blood
pressure, and breathing.
Swelling from injury→ causes pressure, can damage this area,
can cause a coma.

45. Area of the brain
↓
regulates emotion and memory.
connects the lower and higher brain functions.
Components:
A. Cingulate gyrus
B. Fornix
C. Anterior thalamic nuclei
D. Hypothalamus
E. Amygdaloid nucleus
F. Hippocampus & para hippocampus

46. Functions of the limbic system
FEARS (mnemonic)
• Fear, Food habit
• Emotion & Endocrine
• Anger
• Recent memory
• Sexual behaviour,Smell( Olfaction)

47. Reticular Formation
Functions:
• Arousal
• Tonal Modulation
• Pain Processing
• Regulation of
– Vomiting & Coughing
– Respiration
– Speech Functions

48. Clinical relevance of Brain stem
Lesions in the brainstem:
Lesion Vessel involved
1. Medial medullary syndrome Anterior spinal artery
2. Lateral Medullary syndrome Posterior inferior cerebellar artery
3. Medial inferior pontine syndrome Basilar artery
4. Lateral inferior pontine syndrome Anterior inferior cerebellar artery

49. largest part of the hindbrain (posterior cranial fossa behind the pons and
medulla.
Controls the same side body→ directly or indirectly.

50. • covered superiorly → tentorium cerebelli.
• lies posterior to the fourth ventricle
• The cerebellum → 2 Hemispheres →connected by Vermis
• Each hemisphere divided into 3 main lobes:
anterior lobe Posterior lobe flocculonodular lobe
• Cerebellum is functionally divided into 3 lobes:
Paleocerebellum, neocerebellum,Archicerebellum.

52. MORPHOLOGICAL AND FUNCTIONAL DIVISIONS OF
CEREBELLUM
• Made up of flocculonodular lobe and lingula.
• Controls the axial musculature and the bilateral movements used for
locomotion and maintenance of equilibrium.
ARCHICEREBELLUM
• Made up of anterior lobe (except lingula), and the pyramid and uvula of
the inferior vermis.
• Controls tone, posture and crude movements of the limbs.
PALEOCEREBELLUM
• Made up of posterior/middle lobe except the pyramid and uvula of the
inferior vermis.
• Primarily concerned with the regulation of fine movements of the body.
NEOCEREBELLUM

53. ZONES OF THE CEREBELLUM
Functionally, the anterior and posterior lobes are organized into
3 longitudinal zones.
Lateral
• Connected
with
association
areas of brain
• Involved in
planning and
programming
muscular
activities
Intermediate
• Concerned
with control
of muscles of
hands,
fingers, feet
and toes
Vermis
• Concerned
with control
of muscles of
trunk, neck,
shoulders and
hips
Flocculonodular
lobe
• Functions with
vestibular
system in
controlling
equilibrium

54. CONNECTIONS OF CEREBELLUM
• Fibers entering or leaving -cerebellum -form 3 peduncles
1. Superior
2. Middle
3. Inferior

55. Blood Supply of cerebellum
1. Superior surface- Superior CerebellarArtery
2. Inferior Surface- Anterior Inferior Cerebellar Artery
& Posterior Inferior CerebellarArtery
3. The veins drain into neighbouring venous sinuses.

56. FUNCTIONS OF CEREBELLUM
• Coordinates voluntary movements so that they are smooth, balanced and accurate.
• Controls→ tone, posture ＆equilibrium.
• sensory informations to muscles, joints, cutaneous, auditory ＆ visual parts are relayed

57. • Functions as the comparator.
receives information←cerebrum and spinal cord
corrects and modifies → thalamocortical projections, reticulospinal and
rubrospinal tracts.
• Fine tuning of motor performance for precise movements.
• planning and production of skilled movements along with cerebrum.

58. Signs of Cerebellar Lesion
Defect in posture
Hypotonia Decrease muscle tone
Defective attitude Turning of the face to the
opposite side
Vertigo Sensation like the surround
environment
is rotating
Nystagmus Tremor of eyeball when
viewing towards the same
place
Defect in voluntary movement
Asthenia Weakness of the movement
Ataxia Incoordinated movement
Asynergia Incordination between
protogonist & antagonists
Dysmetria Inability to arrest
movement at desired
point.
Gait Reeling, legs wide apart
deviated to the same side
Disadidokinesia Cannot execute rapid
& repeated movement.
Intension tremor Tremor during movement

59. Applied aspects with maxillofacial importance
EPIDURAL AND SUBDURAL HEMATOMA

60. PULSATING EXOPTHALMUS

61. MASTOID PROCESS AND SIGMOID SINUS PROXIMITY

62. References
1. Gray's Anatomy (41st edition)
2. Atlas of Human Anatomy- FH netter
3. Snell Neuroanatomy
4. Pictures- Google and Wikipedia

63. Thank You..