Vasculature of the CNS

Question 1

Arrangement of the arterial supply of the spinal cord

Answer 1

Three longitudinal vessels

Single anterior spinal artery

Paired posterior spinal artery

Question 2

Composition of the anterior spinal artery

Answer 2

Arises in a Y shaped configuration from the two vertebral arteries at the level of the medulla and descends along the ventral suraface of the cord in the midline

Question 3

Formation of the posterior spinal arteries

Answer 3

Arise either from the vertebral arteries or the PICA and run caudally on the posterolateral surface of the cord

Question 4

Additional arterial supply of the spinal cord

Answer 4

Anterior and posterior spinal arteries alone are insufficient to supply the cord below cervical levels and receive serial reinforcement by anastomoses with radicular arteries derived from segmental vessels including the ascending cervical, intercostal and lumbar arteries

Question 5

Passage of radicular arteries

Answer 5

Pass through the intervertebral foramina and divide into anterior and posterior branches which run with the dorsal and ventral spinal roots respsectively.

Question 6

What is one particularly large radicular artetry?

Answer 6

Great radicular artery or artery of Adamkiewicz which may arise from a lateral intercostal or lumbar artery at any level between T8 and L3

Question 7

Where is the blood supply of the spinal cord most vulnerable

Answer 7

In the thoracic region and in the anterior portion of the cord.

Occlusion of the anterior spinal artery leads to an acute thoracic cord syndrome with paraplegia and incontinence.

The spinothalamic modaliteis of pain and tempearture are preferentially lost with relative sparing of the dorsal columns

Question 8

In what layer of spinal cord mater to the spinal arteries run?

Answer 8

Subarachnoid space

Question 9

Venous drainage of the spinal cord

Answer 9

Follows basic pattern of arterial supply.

There are 6 longitudinal venous channels consisting primarily of anterior and posterior spinal veins which run in the midline.

There are sometimes incomplete/irregular bilaterally paired anterolateral and posterolateral veins situated near the sites of the ventral and dorsl nerve roots.

Question 10

How do all of the veins of the spine drain

Answer 10

All drain via the anterior and posterior radicular veins into the internal vertebral venous plexus which is between the dura mater and vertebral periosteum.

Question 11

With what does the internal venous plexus communicate

Answer 11

With an external venous plexus and thence with the ascending lumbar veins, the azygos and hemiazygos

Question 12

Answer 12

Question 13

Answer 13

Question 14

Entry of the ICA to the skull

Answer 14

Arises form the CCA and enters the middle fossa of the cranial cavity via the carotid canal.

Its course then follows a series of bends known as the carotid syphon, after which it passes through the cavernous sinus and then upwards on the medial aspect of the clinoid process, reaching the surface of the brain lateral to the optic chiasm.

Question 15

What are the preterminal branches of the ICA?

Answer 15

Hypohpyseal

Opthalmic

Anterior choroidal

PComm

Question 16

Hypophyseal arteries

Answer 16

Arise from the intra-cavernous section of the ICA to supply the neurohypophysis.

Also form the pituitary portal system.

Question 17

Opthalmic artery

Answer 17

Passes into the orbit through the optic foramen.

Supplies the structures of the orbit, frontal and ethmoidal sinus, frontal part of scalp and dosrum of nose

Question 18

Anterior choroidal artery

Answer 18

Supplies the optic tract, choroid plexus of lateral ventricle, hippocampus and some of the deep structures of the hemisphere including the internal capsule and globus pallidus

Question 19

Calming voices make intra operative surgery pleasurable and almost memorable.

Answer 19

C: caroticotympanic artery (C2)

V: Vidian artery (C2)

M: meningohypophyseal trunk (C4)

I: inferolateral trunk (C4)

O: ophthalmic artery (C6)

S: superior hypophyseal artery (C6)

P: posterior communicating artery (C7)

A: anterior choroidal artery (C7)

A: anterior cerebal artery (C7)

M: middle cerebral artery (C7)

Question 20

Terminal branches of the internal carotid

Answer 20

Lateral to the carotid arteries, the ICA branches into hte ACA and MCA.

Question 21

Passage of the ACA

Answer 21

Courses medially above the optic nerve and passes into the great longiutdinal fissure between the frontal lobes of the cerebral hemispheres.

It is joined to the corresponding vessel of the other side by the AComm.

As it passes down the great longitudinal fissure, the ACA follows the dorsal curvature of the corpus callosum, branches ramifying over the medial surface of the frontal and parietal lobes.

Question 22

Passage of the MCA

Answer 22

Passes laterally to enter the lateral fissure within which it subdivides with its branches supplying virtually the entire lateral surface of the frontal, parietal and temproal lobes.

Question 23

Territory supplied by the ACA

Answer 23

Includes motor and sensory cotrices for the lower limb.

Fine terminal branches also extend out of the great longiutdinal fissure to supply a anrrow lateral band of frontal and pariteral cortices.

Question 24

Territories supplied by the MCA

Answer 24

PRimary motor and senosry cortices for the whole body excluding the lower limb.

Auditory and insula within the depths of the lateral fissure.

Question 25

Passage of the vertebral arteries

Answer 25

Arise from subclavian and ascend through the foramen transversaria of the cervical vertebrae, entering the cranial cavity through the foramen magnum, alongisde the ventrolateral aspect of the medulla. They unite at the medullopontine junction to from the basilar artery.

Question 26

What is the largest branch of the vertebral artery?

Answer 26

The PICA

Question 27

Structures supplied by the AICA

Answer 27

Anterior and inferior portion of the cerebellum

Question 28

Artery which supplies middle ear

Answer 28

Labyrinthine

Question 29

Superior cerebellar artery

Answer 29

Supplies the superior aspect of the cerebellum

Question 30

PCA supplies

Answer 30

Visual cortex of the occipital lobe and the inferomedial aspect of the temporal lobe

Question 31

Branches of vertebral

Answer 31

PICA (basilar) AICA Labyrinthine Pontine SCA PCA PComm

Question 32

What are the two main groups of perforating arteries?

Answer 32

Anterior and posterior

Question 33

Anterior perforating arteries

Answer 33

Arise from the ACA, AComm and the region of origin of the MCA\> Enter the brain in the region between the optic chiasm and the termination of the olfactory tract. Supply large parts of the BG, optic chiasm, internal capsule and hypothalamus

Question 34

Posterior perforating arteries

Answer 34

Arise from PCA and PComm. Enter the brain in the region between the two crura cerebri (posterior perforated substance). Supply the ventral portion of the midbrain and parts of the subthalamus and hypothalamus

Question 35

What are the three sorts of veins that contribute to the venous drainage of the brain?

Answer 35

Deep veins Superficial Veins Dural venous sinuses

Question 36

Answer 36

Question 37

Answer 37

Question 38

Answer 38

Question 39

Deep cerebral veins

Answer 39

Drain the internal structures of the forebrain. Of particular note are the thalamostriate vein and the choroidal vein which drain the BG, thalamus, internal capsule, choroid plexus and hippocampus. Within each hemisphere, these vessels merge to from the internal cerebral vein. The internal cerebral veins unite in the midline to form the great cerebral vein of Galen, which lies beneath the splenium of the corpus callosum. This vein is continuous with the straight sinus poseriorly, which is found in the midline of the tentorium cerebelli

Question 40

Location of the great cerebral vein of Galen

Answer 40

Beneath the splenium of the corpus callosum

Question 41

Location of the straight sinus

Answer 41

Midline of the tentorium cerebelli

Question 42

Superficial veins

Answer 42

Lie within the subarachnoid space. Superior cerebral veins primarily drain the lateral surface of the cerebral hemispheres and empty into the superior sagittal sinus. Superficial middle cerbral vein runs along the line of the lateral fissure and empties into the cavenous sinus. There are two major anastomotoic channels, the superior (great) anastomotic vein, and the inferior anastomotic vein, which drain into the superior sagittal and transverse sinus respsectively.

Question 43

Location of the superficial middle cerebral vein

Answer 43

Along the line of the lateral fissure, emptying into the cavernous sinus

Question 44

Great anastomotic vein drains into

Answer 44

Superior sagittal

Question 45

Inferior anastomotic vein drains into

Answer 45

Transverse sinus

Question 46

Location of the superior sagittal sinus

Answer 46

Along the line of attachment of the falx cerebri.

Question 47

Location of the inferior sagittal sinus

Answer 47

Free borer of the falx cerebri.

Question 48

Drainage of the inferior sagittal sinus is into the

Answer 48

Straight sinus

Question 49

Where do the sagittal sinuses converge

Answer 49

Confluence of sinuses, which is adjacent to the internal occipital protuberance

Question 50

Flow of blood in the dural venous sinuses

Answer 50

From the confluence, to the transverse either side, which lies along the line of attachment of the tentorium to the occipital bone. Transverse sinus is continuous with sigmoid which joins the IJV at the level of the jugular foramen

Question 51

Location of the cavernous sinus

Answer 51

Lateral to the body of the sphenoid. Receives blood from the MCV and drains into the IJV via the inferior petrosal sinus and into the transverse sinus, via the superior petrosal sinus.

Question 52

What connects the two cavernous sinuses?

Answer 52

The intercavernous sinuses, which lie anterior and posterior to the hypophysis, forming a circle around it (circular sinus)

Question 53

Contents of the cavernous sinus OTOM CAt

Answer 53

oculomotor Trochlear Opthalmic Maxillary Cartoid Abducens

Question 54

A patient presents with ophthalmoplegia, proptosis, Horner’s syndrome and sensory loss. You suspect cavernous sinus syndrome. Which of the following nerves do not pass through the cavernous sinus? Abducens nerve Oculomotor nerve Trochlear nerve Maxillary nerve Mandibular nerve

Answer 54

Mandibular nerve Structures passing through each cavernous sinus are: * the internal carotid artery * the abducent nerve (VI). Structures in the lateral wall of each cavernous sinus are, from superior to inferior: * the oculomotor nerve (III) * the trochlear nerve (IV) * the ophthalmic nerve (V1) * the maxillary nerve (V2).

Question 55

Identify the one least appropriate, or false, answer. The primary motor cortex for the upper limb: Lies in the frontal lobe Contains giant Betz cells Is supplied with blood by the anterior cerebral artery Is the site of origin of part of the corticospinal tract

Answer 55

The primary motor cortex for the upper limb is supplied by the middle cerebral artery.