2. What is
brain?
The brain is an amazing three pound
organ (3.3lb, 1.5kg) that controls all
(involuntary & voluntary) function of the
body. Intelligence, creativity, memory
and emotions are few of its function.
3. The average brain weight at the adult male is 1336 gm & for
the female 1198 gm. With increasing age brain weight
decreases by 2.7gm per in male & 2.2 gm in female per year
4. What is
spinal
cord?
The spinal cord is a long fragile tube like
structure that begins at the end of the
brainstem and continuous down to the
level of lumbar region.
11. Embryonic development of the nervous system
● The whole of the nervous system is derived from ectoderm except
its blood vessels and some neuroglia elements.
● Portion of the neural ectoderm layer, neural groove and neural
tube form at about 3 weeks.
Neural
ectoderm
Neural
tube
Neural
crest cells
Ectodermal
placodes
12.
13.
14. Ends of neural plate
● Neural tube: central nervous system
● Neural crest cells: Most of peripheral nervous system
● Ectodermal placodes: Sensory ganglia, Hypophysis, Inner ear
● Neural plate has two ends: cephalic end & caudal end
● Cephalic end give rise to three primary vesicles of the brain
● Caudal end extends to form spinal cord
15.
16.
17.
18.
19.
20. Clinical correlation
● Anencephaly: A failure of the cephalic part of the neural tube to
close and associated defective development of the vault of the skull
produces a congenital anomaly called anencephaly.
● Spinal bifida: Results from incomplete closure of the neural tube
at the caudal end (most commonly in the lumbar region).
● There are three main types of spina bifida of increasing severity:
21. Clinical correlation cont..
● Spina bifida occulta- Incomplete closure of the vertebrae,
without protrusion of the spinal cord
● Meningocele- Where the meninges protrudes between the
vertebrae posteriorly, but the spinal cord is undamaged.
● Myelomeningocele- (Most Severe) Spinal cord remain unfused
and protrudes posteriorly through and opening between the
vertebrae. It is associated with severe disability.
22.
23. Cells of the neural tube
● Cells of the neural tube form two types of cells:
Spongioblast which gives rise to the neuroglia and
neuroblast which gives rise to neuron / nerve cells.
24.
25.
26.
27. Clinical correlation
● In the CNS, the oligodendroglia cells provide the
myelination of the neurons, similar to the role of Schwann
cells in the PNS. Myelination abnormalities can result in
dysfunction in the CNS such as Multiple sclerosis or PNS
such as Guillain-Barre syndrome.
33. Brain (encephalon)
Cerebrum
Brain stem
Cerebellum
• Cerebral hemispheres, thalamus,
hypothalamus, and basal ganglia
● Mid-brain, pons, medulla
Mid-brain contains
cerebral peduncles and
corpus quadrigemnia
34.
35. Cerebrum
● Cerebral hemisphere: grey matter & white matter
● Grey matter: Cerebral cortex & nucleus
● White matter (association & projection pathway):
transverse fibers(commissural fibers), ascending &
descending tract.
● The Cerebral hemisphere is composed of pairs of frontal,
temporal, parietal and occipital lobes.
36. Cont…
● Brodmann has mapped the cortical area of brain (almost 100
different areas are identified)
● Common cortical areas are-
● Area 4 (primary motor cortex)
● Area 3, 2 & 1 (Primary somatic sensory cortex)
● Area 41, 42 (Primary receptive area of sound)
● Area 17 (Primary receptive area of vision)
43. General functions of the cerebral cortex according
to lobes
● Frontal lobe: the major functions of the frontal lobe are high
cognitive function, memory, thinking, reasoning, sensory & motor
functions.
● Major areas are: Area 4 (Anterior to the central fissure-Primary
motor cortex) Controls voluntary motor function.
44. Frontal lobe
● Area 6 & 8 (Motor association area): Area 6: Flexion and
extension of head & extremities mainly hands, turning
head. Area 8: movement of eye ball.
● Area 44 & 45 (Inferior frontal gyrus-Broca’s area): Motor
control of speech. Damage to this area in the dominant
hemisphere results in the inability of the patient to express
his or her thought (non-fluent aphasia)
45. Parietal lobe
● Area 3, 1 & 2 (Posterior to the central fissure - Primary
sensory cortex): Area 1 Cutaneous sensation Area 2 Deep
Sensation Area 3 Touch, Position, Pressure, Vibration
(dominant part involved in ideomotor praxis,
nondominant parietal lobe processes visuospatial
information and control of spatial orientation)
46. Temporal lobe
● Area 41 & 42 (Wernicke’s area - Primary auditory
receptive areas) : Damage in the dominant hemisphere :
Words are heard but they are meaning less to the person
i.e. Fluent aphasia.
● Any destruction of the dominant temporal lobe and
angular gyrus in an adult will result in great impairment
of intellectual ability.
47. Occipital lobe
● The major function of the occipital lobe are visual
perception, some visual reflexes and involuntary smooth
eye movement.
● Area 17: Primary visual cortex
● Area 18 & 19: Visual Association area
48. Basal ganglia
● The basal ganglia are the mass of nuclei located deep in the
cerebral hemispheres. There are three main anatomical parts:
Corpus stratum which include lenticular nucleus (Putamen &
Globus pallidus) Caudate nucleus, Amygdaloid body and the
claustrum.
● These structures in the basal ganglia system are for motor control
of fine body movements, particularly of the hands and lower
extremities
● Disorder of this area produces Parkinson like symptoms.
49.
50.
51.
52.
53.
54.
55.
56. Clinical significance
● Gradual degeneration of part of basal ganglia called
caudate nucleus and putamen causes Huntington disease.
● Parkinson’s disease is caused by a loss of nerve cells in the
part of the brain called the substantia nigra. Nerve cells in
this part of the brain are responsible for producing a
chemical called dopamine.
57. Clinical examination
● Cerebellar: Poor nose to finger proprioception
● Basal ganglia: Good nose to finger proprioception
● Cortical spinal tract: ipsilateral paralysis, paresis (decrease
motor strength) & hypertonia for muscles innervated
caudal to the level of injury. & usually mute planter reflex.
58. Diencephalon
● It is the caudal part of the forebrain (prosencephalon) that
occupies the central region of the brain. The diencephalon is
comprised of the:
● Epithalamus
● Thalamus
● Subthalamus
● Hypothalamus
59.
60. ● The diencephalon acts as a primary relay and processing center for
sensory information and autonomic control. Some of these
connections include pathways to the limbic system (seat of memory
and emotion), basal ganglia (motor coordination), as well as
primary sensory areas, such as auditory or visual.
61. Epithalamus
● It is the most dorsal portion of the diencephalon,
● It is composed of pineal body and other structures.
● Pineal body secretes melatonin, which is important in the
sleep wakefulness cycle.
● Epithalamus is also involved in food & water intake.
62. Thalamus
● The thalamus consist of a pair of egg shaped masses of gray matter
located in the ventromedial part of the hemisphere that has
connection to multiple parts of the brain.
● Thalamus is divided into anterior, posterior & lateral groups and
each group has its own specific nuclei.
63. Thalamus cont..
● Thalamus is the last station where impulses are processed before
they ascends to cerebral cortex.
● Thalamus play a role in conscious pain awareness.
● Focusing and attention
● Reticular activating system
● limbic system (emotions & memory).
64. Hypothalamus
● Located in the basal region of the diencephalon. Forming
part of the walls of the third ventricles.
● The hypothalamus regulates important physiological
drive: Appetite, Sexual arousal, & thirst.
65. Hypothalamus cont…
● It is the centre of autonomic nervous system.
● Hypothalamus controls: temperature, water metabolism,
hypophyseal secretions, visceral & somatic
activities(digestion, urination, heart rate, blood pressure),
visible physical expressions (blushing, dry mouth, clammy
hands) & circadian rhythm.
66. Subthalamus
● The subthalamus is located below the thalamus and is
closely related to the basal ganglia in function.
70. Pons
● The pons is the largest part of the brain stem, lies above medulla
and below midbrain.
● Pons = bridge (between left & right cerebellum)
● It is a group of nerves that function as a connection between the
cerebrum & cerebellum (cortico-pontine cerebellum fibers)
● The pons is a horseshoe shaped collection of nerve fibers located in
the anterior part of the posterior cranial fossa.
71. Anatomical relations
● Posteriorly: the cerebellum,
separated by the fourth
ventricles.
● Inferiorly: the medulla
oblongata.
● Superiorly: the midbrain
72. External anatomy of the pons
● Size around 2.5cm in adult
● Basilar groove in the midline of the ventral surface of the pons.
● The ponto-medullary junction
● Middle cerebellar peduncles.
● Landmarks: middle eminence, facial colliculus & stria medullaris.
73.
74. ● Several cranial nerve originates from the ventral surface of the
pons:
● CN V: Originates from lateral aspect of the mid-pons.
● CN VI: originates from ponto-medullary junction close to midline.
● CN VII: originates from lateral aspect of ponto-medullary junction.
● CN VIII: laterally to facial nerve.
External anatomy of the pons
75. Internal anatomy
● Pontine nuclei: the ventral pons contain pontine nuclei, which is
responsible for coordination & movement.
● Tegmentum: forms the part of RAS, responsible for arousal &
attentiveness.
● Damage to this part may result in anosognosmia for hemiplegia,
where patient are unaware of their paralysis.
76. ● The rest of the pons is made up of tracts that
are passing through:
● Cortico-spinal tract: (Descending) voluntary
motor control of the body
● Cortico-bulbar tract: (Descending)
Voluntary motor control of face, hands &
neck.
● Media lemniscus tract: (Ascending)
responsible for touch, vibration &
proprioception.
● Spinal-thalamic tract: (Ascending)
responsible for pain & temperature
sensations.
Internal anatomy
77. Medulla oblongata
● Medulla is the lower part of the brainstem.
● The medulla oblongata is connected by the pons to the midbrain
and is continuous posteriorly with the spinal cord.
● The main role of the medulla oblongata is in transmitting signals
between the spinal cord and the higher parts of the brain. & in
controlling autonomic activities such as heartrate & respiration.
78. ● The medulla is divided into two main parts: the Ventral medulla
(the frontal portion) and the Dorsal dorsal medulla (tegmentum)
● The ventral medulla contains a pair of triangular structures called
pyramids (within which lies the pyramidal tract ie corticospinal
tract, corticobulbar tract). The ventral medulla also houses another
set of paired structures, the olivary bodies, which are located
laterally on the pyramids.
Medulla oblongata
79. ● The upper part of the medulla forms the lower region of 4th
ventricle.
● The dorsal medulla has the site of origin for the last 4 cranial
nerves.
Medulla oblongata
80.
81.
82.
83. ● About 90% of these fibers the pyramids in successive bundles and
decussate. (Pyramidal decussation or motor decussation) they pass
down into lateral funiculus as the lateral corticospinal tract.
● Other 10% of the fibers stay uncrossed in the anterior corticospinal
tract.
Medulla oblongata
84. Clinical significance
● Injury or disease affecting the middle portion of the medulla may result in
medial medullary syndrome, which is characterized by partial paralysis of the
opposite side of the body, loss of sense of touch and position or partial
paralysis of the tongue.
● Injuries or disease of the lateral medulla cause lateral medullary syndrome,
characterized by loss of pain and temperature sensations, loss of gag reflex,
difficulty in swallowing, vertigo, vomiting or loss of coordination.
85.
86. Cerebellum
● Located in the posterior fossa
● Right cerebellum works in a conjunction with left
hemisphere. Right hemisphere of the brain work in
conjunction with left spinal tract. This is because of cortical
spinal tract
● Makes the roof of 4th ventricle
88. Cerebellum cont..
● The cerebellum is consist of three major layer:
● 1) The cerebellar cortex 2) White matter which forms the
connecting pathways for efferent and afferent impulses joining
with cerebellum with other parts of the CNS. 3) The four pairs of
deep cerebellar nuclei.
● From anterior to posterior direction, the cerebellum is composed of
anterior lobe, posterior lobe and flocculonodular lobe.
89. ● The midline of the anterior & posterior lobe is called as
vermis & the lateral part is called as cerebellar
hemispheres.
● The midline of the flocculonodular lobe is the nodulus &
the lateral portion is called as flocculus.
Cerebellum cont..
93. Functions of the cerebellum
● The anterior lobe: Regulate postural reflexes
● The posterior lobe: Controls Coordination of voluntary muscle
activity & muscle tone.
● The floccunodular lobe: It has the primary connection with
vestibular apparatus for coordination of location in space and
movement.
94. ● The cerebellum is integrated into many connective efferent
and afferent pathways throughout the brain, thus
providing muscles synergy throughout the body.
● In summary, the cerebellum controls fine movement,
coordinate muscle groups and maintain balance.
Functions of the cerebellum
96. Cerebrovascular circulation
● The brain receives approximately 750ml of blood per minute or 15
– 20 % of total resting cardiac output.
● The brain is totally depends upon glucose for its metabolism. A
lack of O2 to the brain for 5 minutes can result in irreversible brain
damage.
● The brain is supplied by two pairs of arteries: Internal carotid
artery & Vertebral artery
107. Artery Goes through & branches Supplied to
Vertebral artery Give rise to posterior circulation of
the brain.
Upper spinal cord
Basilar artery 2 vertebral artery joins to form
basilar artery.
Medial temporal & parietal lobe,
direct supply to brain stem.
Anterior inferior cerebellar artery Branch of basilar artery Anterior & inferior part of
cerebellum
Superior cerebellar artery Branch of basilar artery Dorsal part of the cerebellum
Pontine artery Branch of basilar artery Pons
Medullary artery Branch of basilar artery Medulla
Posterior communicating artery Branch from posterior cerebellar
artery & connects internal carotid
artery to posterior cerebral artery
Medial thalamic surface & third
ventricles
Posterior cerebral artery Branch of basilar artery Occipital lobe, inferior part of
temporal lobe, & deep structures
including thalamus
108. Internal carotid artery Branch of common carotid
artery
Anterior circulation of the Brain & also
supplies blood to eyes
Ophthalmic artery First Branch of internal carotid
artery
Supplies to Orbit, its branches supplies to
nose, face & meninges
Anterior choroidal artery Branch of internal carotid artery Crus cerebri, choroid plexus of lateral
ventricles, globus pallidus, caudate nucleus,
amygdala, red nucleus, hypothalamus,
substantia nigra & optic tract
Middle cerebral artery Largest branch of internal
carotid artery.
Portion of frontal lobe, lateral of temporal
lobe, & parietal lobe (primary motor sensory
cortex), area of speech.
Anterior communicating artery Connects right & left ACA Medial & superior part of frontal lobe,
anterior parietal lobe, optic chiasma, preoptic
& supra optic area, anterior column of fornix.
Anterior cerebral artery Branch of internal carotid artery Midline portion of the frontal lobe, medial
superior parietal lobe.
109. Clinical significance
● Saccular aneurysm are most common.
● In men: ACoA & ACA.
● In women: Junction of ICA, PCoA.
● Giant aneurysm are 3 times more common in women than men.
● Ruptured aneurysm can cause subarachnoid hemorrhage.
● Most common sign is headache.
● SAH is neurosurgical emergency.
111. Spinal cord
● The spinal cord is an elongated mass of nerve tissue that occupies
the upper two third of the vertebral column.
● 42-45 cm long and 1 cm in diameter.
● The spinal cord extends from atlas to lumber vertebra.
● 31 paires (8 cervical, 12 thoracic, 5 lumbar, 5 sacrum & 1 coccygeal)
● Near the spinal nerve each spinal nerve branches into two roots.
Sensory fibers (dorsal root) & motor fibers (ventral root).
● Conus medullaris & Cauda equina
112. ● Conus medullaris:
the terminal end
of the spinal cord.
● Cauda equine
(horse’s tail)
bundle of spinal
nerve rootlets.
Spinal cord
113.
114.
115.
116.
117. Clinical significance
● Conus medullaris syndrome: Compression to T12 to L1
● Cauda equine syndrome: Compression to L1-L5 most often in L3-
L5
● Both the syndrome are neurosurgical emergency, present with back
pain, radiating to the leg, motor and sensory dysfunction, sexual
dysfunction, saddle anesthesia.
118. Primary spinal cord function
● The three main function of spinal cord are:
● The conduction of motor information traveling down the
spinal cord. (Descending)
● The conduction of sensory information in the reverse
direction. (Ascending)
● Spinal cord act as the center for conducting certain
reflexes.
119. The spinal cord in cross section
● Appears like gray H in center surrounded by white matter. [gray
matter consist of cell body & neuronal projections (axon &
dendrites)] [white matter include longitudinal running tract some
of them are myelinated]
● Each funiculus contains ascending and descending tract.
120. ● There are two midline sulci, Anterior (ventral) median fissure &
posterior (dorsal) medial sulci.
● The lateral surface contain both posterolateral and anterolateral
sulci.
● On cross section the gray matter of the spinal cord is divided into
sections called laminae of rexed.
The spinal cord in cross section cont..
121. ● Laminae of rexed through I to X from posterior horn to anterior
horn.
● Laminae I to IV : Sends and receive sensory input.
● IV is located in the intermediate.
● Laminae VIII & IX are present in the anterior horn.
● Laminae IX contains alpha & gamma motor neurons that innervate
skeletal muscles.
● Laminae X is located in the central canal.
The spinal cord in cross section cont..
125. Spinal nerve
● The lumbar and sacral nerve develop from long roots collectively
called as cauda equine.
● There are two enlargements to accommodate innervation to the
extremities. The cervical enlargement to innervates the upper
extremities, extends from C5 to T1 and the lower extremities are
innervated by lumbosacral enlargement which extends from L1 to
S3.
● Spinal nerves has two roots: Sensory (Dorsal) & Motor (Ventral)
126. Sensory (Dorsal) roots
● The dorsal roots convey sensory input (AFFERENT IMPULSES)
from specific areas of the body known as dermatomes.
● The sensory fibers are of two types: General sensory afferent fibers
& General visceral afferent fibers.
● GSA fibers: carry sensory impulses for pain, temperature, touch &
proprioception from the body skin tendons and joints.
● GVA fibers: carry sensory impulses from the organs within the
body
127.
128.
129. Sensory nerve roots & the areas they innervate
Spinal nerve Dermatome
C2 Occiput
C3 Neck
C4 Neck & upper shoulder
C5 Lateral aspect of shoulder
C6 Thumb, radial aspect of arm, index finger.
C7 Middle finger, middle palm & back of the hands.
C8 Ring & little finger, ulnar forearm.
130.
131. Sensory nerve roots & the areas they innervate
T1-T2 Inner aspect of arm & across shoulder blade
T4 Nipple line
T7 Lower costal margin
T10 Umbilical region
T12-L1 Inguinal region
L2 Anterior thigh & upper buttocks
L3-L4 Anterior knee & lower leg
L5 outer aspect of lower leg, dorsum of foot & great toe
S1 Sole of foot & small toe
S2 Posterior medial thigh & lower leg
S3 Medial thigh
S4-S5 Genitals and saddle area
132. Motor (ventral) roots
● The ventral root convey efferent impulses from the spinal cord to the body.
● The motor fibers are of two types: General somatic efferent fibers & General
visceral efferent fibers.
● GSE fibers: Which innervate voluntary striated muscles and have axons
originating from the alpha & gamma motor neurons of lamina IX
● GVE fibers: Which include the preganglionic & postganglionic autonomic
fibers that innervate smooth muscles & also regulate glandular secretions.
● Both alpha & gamma motor neurons are also called as lower motor neurons
133.
134. Motor nerve root & the areas they innervate
C1-C4 Neck (flexion, extension, lateral flexion & rotation)
C3-C5 Diaphragm (respiration)
C5-C6 Shoulder movement & flexion of elbow
C5-C7 Forward thrust of shoulder
C5-C8 Adduction of arm from front to back
C6-C8 Extension of forearm and wrist
C7, C8, T1 Flexion of wrist
T1-T12 Control of thoracic, abdominal & back muscles.
L1-L3 Flexion of hip
L2-L4 Extension of leg & adduction of thigh
L4 L5 S1 S2 Abduction of thigh, flexion of lower leg
L4 L5 Dorsal flexion of foot
L5 S1 S2 Planter flexion of foot
S2 S3 S4 Perineal area and sphincters
135.
136.
137. Classification of peripheral nerve fibers
● According to ERLANGER & GASSER (M/S/A).
● Other classification is LLOYD classification (sensory only).
● Group A . Divides into Aalpha, A alpha is further dvided into somatic motor & somatic sensory
(proprisocepton) or type I fibers.
● Type I is divided into Ia
138. Erlanger & gasser system
Fiber types Sub-types Function Features
A (myelinated) Alpha (motor + sensory)
• Somatic motor
• Somatic sensory Proprioception
Beta (sensory) (BVProLT) Vibration, proprioception, light touch
Gamma (motor) Muscle
spindle
Delta (sensory) Fast pain & cold temperature.
B (pre-ganglionic
autonomic fibers)
(myelinated)
C Pressure, slow pain, crude touch,
(cold+warm)temperature
Post ganglionic (sympathetic)
139. LLOYD’S CLASSIFICATION
Fiber types Sub-types Function Features
I (somatic sensory) IA
IB
Muscle spindle
Tendons
Changes in length
Changes in tension
II (beta fibers) Muscle spindles Vibration, proprioception, light
touch
III (delta) Fast pain & cold temperature.
IV
143. Views
● Norma frontalis (anterior)
● Norma lateralis (lateral view)
● Norma verticalis (superior)
● Norma occipitalis (inferior)
● Norma basalis (base of the skull)
● Internal of the skull (internal of calvarium & internal of base of the
skull)
144. Norma frontalis
● Neurocranium (8) (unpaired ethmoid(middle, superior nasal
concha is a part of ethmoid), sphenoid, frontal & occipital bone)
(paired 2 parietal, 2 temporal)
● Splanchno cranium (14) (2 unpaired mandible, vomer) (6 paired
maxilla, zygomatic bone, nasal bone, lachrymal bone, palatine
bone, inferior nasal concha)
![Clinical Neuro
Anatomy
Evaluator: Mr L Anand Presenter: Shruti Shirke
[Asso professor, CON AIIMS BBSR] M.Sc Neuroscience Nursing](https://image.slidesharecdn.com/neuro-anatomy-copy-210806045818/85/Neuro-anatomy-1-320.jpg)
