Blood Supply, Hemorrhage and Herniation of the Brain

Question 1

Border zones

Answer 1

Area between arteries

Susceptible to damage under conditions of sudden systemic hypotension or hypoperfusion

Question 2

Anterior cerebral artery

Answer 2

Supplies most of the medial and superior surface of the frontal and parietal lobes

Question 3

Middle cerebral artery

Answer 3

Supplies lateral surface of frontal and parietal lobes and the superior part of temporal lobe

Question 4

Posterior cerebral artery

Answer 4

Supplies the occipital lobe and the inferior parietal lobe

Question 5

Segments of anterior cerebral artery

Answer 5

A1- precommunicating segment- ICA to anterior communicating artery
A2- infracallosal segment- anterior communicating artery to where rostrum and genu of corpus callosum meet
A3- precallosal segment- arches around the genu of corpus callosum, ends when vessels turn caudal
A4- supracallosal- superior to corpus callosum
A5- postcallosal- caudal to corpus callosum

Question 6

Segments of middle cerebral artery

Answer 6

M1- sphenoidal or horizontal- ICA to the bifurcation at insula
M2- insular- bifurcation at insula to circular sulcus of insula
M3- opercular- circular sulcus of insula to external surface of lateral fissure
M4- cortical- on the cortex

Question 7

Segments of posterior cerebral artery

Answer 7

P1- basilar bifurcation to posterior communicating artery
P2- posterior communicating artery to around the midbrain
P3- quadrigeminal- segment within the quadrigeminal cistern
P4- cortical segment

Question 8

Parts of the internal carotid artery

Answer 8

Cervical- bifurcation to carotid canal, anterior to transverse processes of upper 3 vertebrae
Petrous- carotid canal in petrous part of temporal, upward and medially above foramen lacerum
Cavernous- in the cavernous sinus, surround by sympathetic plexus, CN III, IV, VI and V1
Cerebral part

Question 9

Vertebral artery parts

Answer 9

Cervical- transverse foramina of first 6 cervical vertebrae
Atlantic- perforates the dura and arachnoid, pass through foramen magnum
Intracranial- in the cranium, unite at the caudal border of pons to form basilar artery

Question 10

Cranial nerves association to arteries CN II, III and VI

Answer 10

CN II is near ICA, anterior cerebral and anterior communicating artery
CN III is near posterior cerebral a, superior cerebellar a, and posterior communicating a
CN VI is near labyrinthine and AICA

Question 11

Circle of willis

Answer 11

A ring of 9 arteries supplying blood to the cerebral hemispheres
2 anterior cerebral a.
2 internal carotid a.
2 posterior cerebral a.
Anterior communicating artery
2 posterior communicating a.
Located in the subarachnoid space

Question 12

Intracerebral (subpial) hemorrhage

Answer 12

Bleeding within brain substance (stroke)
Complication in 2-3% of all head injuries
Source is usually middle cerebral artery
Hypertension or degenerative artery disease is commonly found at autopsy

Question 13

Causes of herniation syndromes

Answer 13

Hemorrhage
Mass/tumor
Trauma
Abscess
Infection
Metabolic conditions

Question 14

Divisions of herniation syndromes

Answer 14

Supratentorial compartment- above the tentorium and divided into right/left by falx cerebri
Infratentorial compartment- below tentorium cerebelli
Tentorial notch- continuation of the supra and infratentorial compartment

Question 15

Subfalcine herniation

Answer 15

Also called a cingulate or falcine or falx herniation
Supratentorial compartment has mass/lesion- displaces brain tissue under the falx cerebri
May compress the ACA- frontal/parietal lobes affected
May evolve into a transtentorial herniation

Question 16

Transtentorial herniation

Answer 16

Also called central herniation
Brain displaced downward toward tentorial notch
Comprises the upper brainstem, CN III and possibly even lower structures. May compress basilar artery and posterior cerebral arteries
Decorticate rigidity
Decerebrate rigidity

Question 17

Uncal herniation

Answer 17

Uncus and frequently portions of the parahippocampal gyrus are extruded over the edge of tentorium cerebelli and through the tentorial notch

• Impinge on midbrain
• Can damage cerebral peduncle & oculomotor nerve and cause motor deficits on opposite side of body

Question 18

Tonsillar herniation

Answer 18

Cerebellar tonsil through foramen magnum

Compression of the medulla and upper cervical spinal cord

Question 19

Vertebrobasilar insufficiency

Answer 19

Reduced blood flow to brain from vertebral arteries

Can be caused by extreme hyperextension of the head or extreme head rotation

Question 20

Subclavian steel syndrome

Answer 20

Occlusion of subclavian artery proximal to the vertebral artery. Blood is stolen from vertebral circulation to supply upper limbs

Question 21

Trigeminal nerve is by which arteries

Answer 21

Superior cerebellar artery

Question 22

Facial nerve is by which arteries

Answer 22

Anterior inferior cerebellar artery

Question 23

Damage to border zone b/w anterior cerebral and middle cerebral arteries will cause what

Answer 23

Motor, sensory deficits
Language issues
Behavioral problems

Question 24

Damage to posterior border zone b/w posterior cerebral and middle cerebral artery will cause what

Answer 24

Visual and language problems

Question 25

What artery since right up against corpus callosum

Answer 25

Pericallosal artery

Question 26

What artery is around cingulate gyrus

Answer 26

Callosomarginal artery

Question 27

Anterior spinal artery supplies what

Answer 27

Medial aspect of medulla

Question 28

Posterior inferior cerebellar artery PICA supplies what

Answer 28

``` Lateral aspect of medulla Medial/inferior vestibular nucleus Accessory cuneate nucleus Solitary tract/nucleus Dorsal motor nucleus of vagus (autonomics) Spinal trigeminal tract/nucleus Rubrospinal tract ALS Nucleus ambiguous (motor tract) ```

Question 29

Anterior inferior cerebellar artery supplies what

Answer 29

Cochlear nuclei (CNVIII)

Question 30

Posterior spinal artery supplies what

Answer 30

Dorsal aspect of medulla

Question 31

What arteries branch off anterior spinal artery to supply medulla and what do they supply

Answer 31

Sulcal arteries Pyramid (motor) tract Medial lemniscus (sensory tract) Hypoglossal nucleus

Question 32

Blood supply to pons is via

Answer 32

Branches off basilar artery and superior cerebellar artery in more rostral regions

Question 33

Blood supply to midbrain is via

Answer 33

Posterior cerebral artery branches

Question 34

P1 anteromedial segment of PCA supplies

Answer 34

``` Medial portion of midbrain Oculomotor nucleus Medial longitudinal nucleus Substantia niagra Red nucleus Parts of oculomotor nerve ```

Question 35

Thalamogeniculate branches of P2 supply what

Answer 35

Lateral and medial geniculate nuclei in forebrain

Question 36

Lenticulostriate arteries supply what and is a branch off what artery

Answer 36

Internal capsule | Branch of middle cerebral artery

Question 37

Epidural hematoma information

Answer 37

Bleeds into potential space of skull and dura Common site: pterion or squamous temporal bone Source: middle meningeal artery Clinical- momentary unconsciousness followed by lucidness for a few hours to 1-2 days then unconsciousness

Question 38

Subdural hematoma information

Answer 38

B/w dura and arachnoid Seen when head strikes a fixed object Venous source of bleeding- usually cortical veins opening into superior sagittal sinus Clinical- slower accumulation of blood due to pressure and often self limiting Lumbar puncture can cause subdural hematoma

Question 39

Kernohan phenomenon

Answer 39

Variation of uncle herniation that shifts the midbrain Still hits oculomotor nerve on same side but compresses cerebral peduncle on OPPOSITE side, giving motor deficits on the same side

Question 40

Long circumferential branches of basilar artery supply

Answer 40

``` Lateral, superolateral pons Facial nerve, facial motor nucleus Spinal trigeminal tract/nucleus Mesencephalic nucleus/tract ALS ```

Question 41

Paramedian branches of basilar artery supply

Answer 41

``` Medial pons Corticospinal fibers Medial lemniscus Abducens nerve/nucleus Medial longitudinal fasciculus ```