these structutes are foun in the brain that has a proper function

1. 08-12-2019

3. INTRODUCTION
• Brainstem is the part of brain formed by:
a) medulla oblongata.
b) Pons.
c) midbrain.
• Brainstem contains ascending and descending
tracts between brain and spinal cord.
• It also contains many centers for regulation of
vital functions in the body.
• Brainstem also contain most cranial nerve.

4. 1- MIDBRAIN:
• Midbrain lies between pons and diencephalon.
• It consists of two parts:
A. Tectum
B. Cerebral peduncles.
• Tectum is formed by two structures:
1. Superior colliculus: (center for reflexes).
A. Controls the movements of the eyes, head, trunk and
limbs, in response to visual impulses.
B. Center for light reflex.
C. Integration of optical and postural reflexes.
2. Inferior colliculus: (center for auditory reflexes)
• Production of reflex vocalization.

5. • Cerebral peduncles include:
1. Basis pedunculi:
2. Substantia nigra
3. Tegmentum, which includes “Red nucleus”.
• Tegmentum comprises three decussations and
red nucleus.
A. Superior cerebellar peduncle.
B. Forel decussation.
C. Meynert decussation.

6. • Red Nucleus:
• is a large oval or round mass of gray matter, extending
between the superior colliculus and hypothalamus.
1. Nucleus magnocellularis, which is formed by large cells.
Fibers from this form the rubrospinal and rubrobulbar
tracts.
2. Nucleus parvocellularis, which is formed by smaller cells.
Fibers from this form mainly the rubroreticular tract.
• Connections of red nucleus:
A. Afferent connections.
B. Efferent connections: Red nucleus sends efferent fibers to
various parts of brain and spinal cord.

7. • Afferent connections: Red nucleus receives fibers from:
1. Nucleus parvocellularis, which receives fibers from motor
cortex (area 6) – corticorubral fibers.
2. Nucleus magnocellularis, which receives fibers from motor
cortex (area 6) – pallidorubral fibers
3. Nucleus magnocellularis, which receives fibers from
dentate nucleus (of opposite side) – cerebellorubral or
dentatorubral tract.
• Efferent connections: Red nucleus sends efferent fibers to
various parts of brain and spinal cord:
1. Rubrospinal tract to spinal cord.
2. Rubrobulbar tract to medulla
3. Rubroreticular fibers to reticular formation
4. Rubrothalamic tract to lateral ventral nucleus of thalamus
5. Rubroolivary tract to inferior olivary nucleus
6. Fibers to nuclei of 3rd, 4th and 6th cranial nerves.

8. 1. Control of muscle tone.
2. Control of complex muscular movements.
3. Control of righting reflexes (upright position of
the body).
4. Control of movements of eyeball.
5. Control of skilled movements.

9. 2- PONS:
• Pons forms a bridge between medulla and midbrain.
1. Axons of pontine nuclei join to form the middle cerebellar
peduncle or the brachium pontis.
• Pons forms the pathway that connects cerebellum with
cerebral cortex.
2. Pyramidal tracts pass through the pons
3. Medial lemniscus is joined by the fibers of 10th, 9th, 7th
and 5th cranial nerves in pons
4. Nuclei of 8th, 7th, 6th and 5th cranial nerves are located in
pons
5. Pons contains the pneumotaxic and apneustic centers for
regulation of respiration
6. It also contains the vestibular nuclei.

10. 3-MEDULLA OBLONGATA:
• Medulla oblongata or medulla is the lowermost
part of brain.
• It is situated below pons and is continued
downwards as spinal cord.
• Medulla forms the main pathway for ascending
and descending tracts of the spinal cord.
• It also has many important centers which control
the vital functions.
• All the medullary centers and nuclei of cranial
nerves are controlled by higher centers, situated
in cerebral cortex and hypothalamus.

11. 1. Respiratory Centers (maintain normal rhythmic respiration).
2. Vasomotor Center (controls blood pressure and heart rate).
3. Deglutition Center (pharyngeal and esophageal stages of
deglutition).
4. Vomiting Center (irritation or inflammation of gastrointestinal
(GI) tract).
5. Superior and Inferior Salivatory Nuclei (secretion of saliva).
6. Vestibular Nuclei
7. Cranial Nerve Nuclei:
• (Nuclei of 12th{hypoglossal} - controls the movements of tongue,
11th{accessory} - controls the movements of shoulder, 10th{vagus} -
controls almost all the vital functions in the body).
• Some nuclei of 8th {cochlear} - concerned with the auditory
function, and 5th- cranial nerves

14. • Thalamus is a large ovoid
mass of gray matter, situated
bilaterally in diencephalon.
Both thalami form 80% of
diencephalon.
• Thalamus on each side is
divided into five main
nuclear groups by ‘Y’-shaped
internal medullary lamina:
1. Midline nuclei.
2. Intralaminar nuclei.
3. Medial mass of nuclei.
4. Lateral mass of nuclei.
5. Posterior group of nuclei.
• Bondok classification.
• Five groups of thalamic
nuclei are:
1. Specific sensory relay nuclei
2. Specific motor nuclei
3. Association or less specific
nuclei
4. Non-specific nuclei
5. Limbic system nuclei.

16. Thalamic radiation:
• Fibers of thalamic radiation are divided into four
groups, which are called thalamic peduncles or
thalamic stalks:
1. Anterior (Frontal) Thalamic Peduncle Or Radiation
= It contains mostly motor nerve fibers.
2. Superior (Centroparietal) Thalamic Peduncle Or
Radiation = It contains mainly the sensory fibers.
3. Posterior (Occipital) Thalamic Peduncle Or
Radiation = It contains the nerve fibers concerned
with vision.
4. Inferior (Temporal) Thalamic Peduncle Or
Radiation = contains the nerve fibers concerned
with hearing.

17. FUNCTIONS OF THALAMUS:
• Thalamus is primarily concerned with somatic functions and it
plays little role in the visceral functions.
1. RELAY CENTER: relay center for the sensations.
2. CENTER FOR PROCESSING OF SENSORY INFORMATION:
sensory impulses integrated and modified before being sent to
specific areas of cerebral cortex.
3. CENTER FOR DETERMINING QUALITY OF SENSATIONS:
Discriminative nature is the ability to recognize the type,
location and other details of the sensations - Affective nature:
is the capacity to determine whether a sensation is pleasant or
unpleasant and agreeable or disagreeable.
4. CENTER FOR SEXUAL SENSATIONS: perception of sexual
sensations.
5. ROLE IN AROUSAL AND ALERTNESS REACTIONS.
6. CENTER FOR REFLEX ACTIVITY.
7. CENTER FOR INTEGRATION OF MOTOR ACTIVITY.

19. • Internal capsule is the broad and compact
band of afferent and efferent fibers
connecting cerebral cortex with brainstem and
spinal cord.
• Internal capsule is situated in between
thalamus and caudate nucleus on the medial
side and lenticular nucleus on the lateral side.

21. • Hypothalamus is a diencephalic structure.
• Hypothalamus is the important part of brain, concerned
with homeostasis of the body.
• It regulates many vital functions of the body like
endocrine functions, visceral functions, metabolic
activities, hunger, thirst, sleep, wakefulness, emotion,
sexual functions, etc
• Nuclei of hypothalamus are divided into three groups:
1. Anterior or preoptic group.
2. Middle or tuberal group.
3. Posterior or mamillary group.

22. FUNCTIONS OF HYPOTHALAMUS
1. SECRETION OF POSTERIOR PITUITARY
HORMONES: ADH and oxytocin.
2. CONTROL OF ANTERIOR PITUITARY: secreting
releasing hormones and inhibitory hormones.
3. CONTROL OF ADRENAL CORTEX and ADRENAL
MEDULLA.
4. REGULATION OF AUTONOMIC NERVOUS
SYSTEM.
5. REGULATION OF HEART RATE and BLOOD
PRESSURE.
6. REGULATION OF BODY TEMPERATURE.

23. 7. REGULATION OF HUNGER AND FOOD INTAKE.
8. REGULATION OF WATER BALANCE.
9. REGULATION OF SLEEP AND WAKEFULNESS.
10. ROLE IN BEHAVIOR AND EMOTIONAL.
CHANGES: reward (satisfaction) and punishment
(aversion or avoidance).
11. REGULATION OF SEXUAL FUNCTION.
12. ROLE IN RESPONSE TO SMELL.
13. ROLE IN CIRCADIAN RHYTHM.

25. • Cerebellum consists of a narrow, worm-like central
body called vermis and two lateral lobes, the right
and left cerebellar hemispheres.
• Cerebellum is made up of outer gray matter or
cerebellar cortex and an inner white matter.
• White matter is formed by afferent and efferent
nerve fibers of cerebellum.
• Gray masses called cerebellar nuclei are located
within the white matter.

26. DIVISIONS OF CEREBELLUM
A) ANATOMICAL DIVISIONS:
1. Anterior Lobe.
2. Posterior Lobe.
3. Flocculonodular Lobe
B) PHYLOGENETIC DIVISIONS:
1. Paleocerebellum
2. Neocerebellum.
C) FUNCTIONAL DIVISIONS:
1. Vestibulocerebellum
2. Spinocerebellum
3. Corticocerebellum.

29. CEREBELLAR NUCLEI:
1. Fastigial Nucleus.
2. Globosus Nucleus.
3. Emboliform Nucleus.
4. Dentate Nucleus
WHITE MATTER OF
CEREBELLUM:
1. Inferior Peduncles
(restiform bodies)
2. Middle Peduncles (brachia
pontis)
3. Superior Peduncles
(brachia conjunctivae)

30. Function:
1- VESTIBULOCEREBELLUM (ARCHICEREBELLUM):
• Maintenance of posture and equilibrium.
• Regulates tone.
• Facilitate the movements of trunk, neck and limbs through
vestibulospinal tracts and alpha motor neurons.
2- SPINOCEREBELLUM (PALEOCEREBELLUM):
• Maintenance of muscle tone and anticipatory adjustment
of muscle contraction during movement.
• Receiving area for tactile, proprioceptive, auditory and
visual impulses.
3- CORTICOCEREBELLUM (NEOCEREBELLUM):
• Planning, programming and coordination of skilled
movements.

31. i. Damping action: refers to prevention of exaggerated muscular
activity.
ii. Ballistic movements: are the rapid alternate movements, which take
place in different parts of the body while doing any skilled or trained
work like typing, cycling, dancing, etc.
iii. Timing and programming the movements: plans schedule of time
duration of each movement and the time interval between
movements.
iv. Servomechanism: is the correction of any disturbance or interference
while performing skilled work.
v. Comparator function: of the corticocerebellum is responsible for the
integration and coordination of the various muscular activities.

33. • Basal ganglia are the scattered masses of gray matter
submerged in subcortical substance of cerebral
hemisphere.
• Basal ganglia form the part of extra-pyramidal system,
which is concerned with motor activities.
• Basal ganglia include three primary components:
1. Corpus striatum: mass of gray matter situated at the base
of cerebral hemispheres in close relation to thalamus.
i. Caudate nucleus
ii. Lenticular nucleus.
2. Substantia nigra: situated below red nucleus. It is made up
of large pigmented (Iron) and small nonpigmented cells.
3. Subthalamic nucleus of Luys: situated lateral to red
nucleus and dorsal to substantia nigra.

34. FUNCTIONS OF BASAL GANGLIA:
1. CONTROL OF MUSCLE TONE.
2. CONTROL OF MOTOR ACTIVITY:
A. Regulation of Voluntary Movements
B. Regulation of Conscious Movements (when a stray dog barks at a man,
immediately the person, understands the situation, turns away and
starts running)
C. Regulation of Subconscious Movements (writing the learnt alphabet,
paper cutting, nail hammering).
3. CONTROL OF REFLEX MUSCULAR ACTIVITY: visual and labyrinthine
reflexes.
4. CONTROL OF AUTOMATIC ASSOCIATED MOVEMENTS: swing of the
arms while walking.
5. ROLE IN AROUSAL MECHANISM
6. ROLE OF NEUROTRANSMITTERS IN THE FUNCTIONS OF BASAL
GANGLIA