2. THE BRAIN
•Large mass of nervous tissue located in cranialcavity.
•Has four major regions.
Cerebrum
(Cerebral hemispheres)
Diencephalon: Thalamus,
Hypothalamus,
Subthalamus & Epithalamus
Cerebellum
Brainstem: Midbrain, Pons & Medulla oblongata
3. BLOOD SUPPLY OF BRAIN
• Brain Receives 17% of cardiac output
• Consumes 20% of entire Oxygen used by the
body
• 10 seconds of interruption in blood flow leads to
unconsciousness
• Most neurologic disorders are due to vascular
lesions
5. ANTERIOR CIRCULATION
INTERNAL CAROTID artery Course
it arises from the common carotid artery at the level of c4
vertebrae
• Enters into Middle cranial fossa through carotid canal and
then enters through foramen lacerum into cavernous sinus
Pierces dura and arachnoid maters.
• It ends by Dividing into Anterior and Middle cerebral
arteries.
6. Branches of internal carotid artery
1. Opthalmic artery
2. Posterior communicating
artery
3. Anterior choroidal artery
4. Bifurcates into anterior
cerebral artery and middle
cerebral artery .
7. ANTERIOR CHOROIDAL ARTERY
• Branch of internal carotid artery
• Supplies posterior limb of internal capsule, retrolentiform and
sublentiform parts
• Complete syndrome rare due to collaterals from MCA, PCA, and ICA
• Syndrome comprises
• c/l hemiplegia
• c/l hemianaesthesia
• c/l homonymous hemianopia
8. Anterior cerebral artery
the two anterior cerebral arteries joined together by anterior
communicating artery.
• Brain supplied by anterior cerebral artery
Frontal pole
Medial aspects of frontal and parietal lobes
Basal ganglia
Corpus callosum
9. Anterior Cerebral artery
A1 segment- proximal to anterior communicating artery
it gives branches to
anterior limb of internal capsule
anteroinferior caudate
anterior hypothalamus
A1 segment occlusion are rarely produces clinical syndrome because collateral flow
through anterior communicating artery and collaterals from MCA and PCA
10. A2 SEGMENT
• Part of anterior cerebral artery distal to anterior communicating
artery
• supplies frontal pole , entire medial part of frontal and parietal lobe.
A2 SYNDROME
Lesion of A2 segment causes paralysis and sensory loss of C/L foot and
leg and involvement of paracentral lobule causes urinary
incontinence.
11.
12. MIDDLE CEREBRAL ARTERY
• It arises from the internal carotid and continues into the later sulcus
where it then branches and projects to lateral cerebral cortex.
13. Middle cerebral Artery
M1 SEGMENT(proximal)-it gives deep penetrating or
lenticulostriate branches which supplies Internal capsule,
caudate nuclues, putamen and outer pallidus
M1 SYNDROME-occlusion of lenticulostriate branches-
Involvement of internal capsule produces contralateral
hemiplegia.
Involvement of putamen, pallidus- leads to parkinsonian
features.
14. Blood supply of internal capusle
Upper part ; lenticulo striate braches of MCA
LOWER PART : anterior chorodial artery
15. M2 Segment
It has superior and inferior divisions
supplies the entire superiolateral
surface of cerebral hemispheres .
Except
• frontal pole
• strip along the superiomedial frontal
and parietal cortex
• medial temporal cortex
• occipital lobe
16. M2 syndromes
• If superior division involved
• Brachial syndrome- weakness of hand and arm
• Frontal opercular syndrome-Brocas aphasia with facial weakness with or
without arm weakness
• proximal part of the superior division involved- clinical features of motor
weakness, sensory disturbances and brocas aphasia
• If inferior division of M2 involved-
• If dominant hemisphere- Wernickes aphasia without weakness with
contralateral homonymous superior quadrantanopia
• If non dominant hemisphere- Hemispatial neglect , spatial agonosia
without weakness
17. Complete MCA syndrome
• occulsion of both M1 AND M2 SEGEMENT IS COMPLETE MCA SYNDROME.
CLINICAL FEATURES
• Contralateral hemiplegia
• Contralateral hemianaesthesia
• Contralateral homonymous hemianopia
• If dominant hemisphere involved-Global aphasia
• If non dominant hemisphere involved- Hemispatial neglect, and
constructional apraxia
18. CIRCLE OF WILLS
o It is Formed by:
Two Anterior cerebral arteries
Two Internal carotid arteries
Two Posterior cerebral arteries
Two Posterior communicating arteries
One Anterior communicating artery
24. P2 syndromes
• ANTONS SYNDROME-bilateral occlusion in distal PCAs – bilateral
occipital lobe infarction- cortical blindness and patient often unaware
and even deny it
• BALINTS SYNDROME-bilateral visual association areas- palinopsia and
asimultagnosia
29. Lateral medullary syndrome(Wallenburgs)
Structure Clinical features
Spinothalamic tract Contralateral decreased pain and temperature
Spinocerebellar tract Ipsilateral ataxia
Sympathetic fibers Horners syndrome
Spinal trigeminal tract and nucleus(5th) Pain and numbness over Ipsilateral half of the face
Nucleus ambiguus Dysphagia,hoarseness
Vestibular nuclei Vertigo,nausea
30. Medial medullary syndrome
Structure involved Clinical features
pyramid Contralateral hemiplegia
medial lemniscus contralateral loss of tactile and proprioception
hypoglossal nerve nucleus (12 th) Ipsilateral atrophy of half of tongue.
