13. Axial CT
Posterior genu as it
courses anteromedially
into the cavernous sinus
ICA courses along the
basisphenoid bone
• Through cavernous sinus proper turns superiorly
• Form grooves under anterior clinoid process
•Curve upwards towards dural ring
• Enter subarachnoid space
Posterior genu
Carotid sulcus
Anterior genu
14.
15. •Between proximal , distal dural rings of
cavernous sinus
•Ends as ICA enters subarachnoid space near
anterior clinoid process
•No important branches
16. Extends from distal dural ring at
superior clinoid to just below
posterior communicating artery
(PCOM) origin
Branches –
•Ophthalmic artery
•Superior hypophyseal artery
Anterior clinoid process C6
17.
18.
19.
20.
21. •In utero – embryonic trigeminal artery supplies basilar artery before the PCOM and vertebral
artery develops
course – arise when ICA exits carotid canal and enters
cavernous sinus
Runs posterolaterally along trigeminal nerve 41%
Crosses over / through dorsum sella before
joining basilar artery
Connects ICA to vertebrobasilar system
trident shape on lateral DSA
22. •PCOM is absent
•Supply entire vertebrobasilar circulation distal to
anastomosis
Saltzmann type
Ι
• Fetal PCA and I/L P1 segment absent
• Fill superior cerebral arteries (SCA) with posterior
cerebral arteries (PCA ) fills via patent PCOM
Saltzmann type
ΙΙ
•Increased incidence of intracranial aneurysms / malformations
•Increased importance in transphenoidal surgery
23.
24.
25.
26.
27.
28. • Anterior two-thirds of the medial
surface of the hemisphere
• Small wedge along the inferomedial
frontal lobe
• Cortex over the top of the
hemisphere vertex
computer technique which compares an x-ray image of a region of the body before and after radiopaque iodine based dy Tissues and blood vessels on the first image are digitally subtracted from the second image//C/I allergic reaction, renal failure, anticoagulant
Gd contrast shortens T1 relaxation time of blood.//tof GRE sequence uses short Tr freshly flowing blood is not saturated , stationary are saturated and get suppressed d/trecurrent rf pulses
Time-of-flight (non-contrast) MR angiogram, frontal view. The great vessels.
The C2 (petrous) segment is long and L-shaped. C3 is a short segment between C2 and the cavernous ICA (C4) . C5 is the last extradural segment. Posterior ,
anterior genu of C4 are shown.
Extracranial part of ICA//3D CTA
- Surrounded by extensive sympathetic plexus
he C4 (cavernous) segment has both a posterior and an anterior genu. Together, they form the angio-DSA carotid “siphon.”
Three subsegments joined by two genus (knees) - Posterior vertical (ascending) portion - Posterior (more medial) genu - Horizontal segment - Anterior (more lateral) genu - Anterior vertical (subclinoid) segment//anastomoses with ECA branches through foramens rotundum, spinosum, ovale
Lies in subarachnoid space
Axial graphic illustrates a classic aberrant ICA arising along the posterior cochlear promontory and
crossing along the middle ear to rejoin the horizontal petrous ICA. A stenosis is often present at the
reconnection site. 8-4. Axial CTA source image through the middle ear shows an AbICA looping over the
cochlear promontory.
Axial temporal bone CT shows an enlarged anterior tympanic segment of the facial nerve canal .instead of ECA
(A) Schematic diagram showing the series of embryonic anastomoses between the anterior and posterior circulation
which form and regress until the final one, the posterior communicating artery, is established. (B) DSA: the persistent trigeminal artery
(small arrow) is most frequently encountered.
2 ica, 2 aca acaom 2 pcom 2 pca basillar
Submentovertex view of normal MRA shows the ACoA , small PCoAs , basilar bifurcation with
large P1 PCA segments forming a “balanced” circle of Willis.
Smaller of the two terminal Ica branches// A1 segmet medial lenticulostriate arteries , head of caudate nucleus and ant limb of internal capsule (medial part of basal ganglia)
A2
. Sagittal midline MIP of CTA shows A2 segments of both ACAs ascending in the interhemispheric fissure in front of the third ventricle, A3 segments curving around the corpus callosum genu.//AP view of a normal internal carotid DSA shows the ACA “wandering” gently from side to side
across the midline in the interhemispheric fissure.
coursing laterally into the lateral sulcus// lateral lenticulostriate, supplies lateral putamen external capsule and caudate nucleus//anterior temporal branches-tip o temporal lobe
Terminal branches of the basilar artery
P2 PCAs and the medial course of the P3 segments as they pass behind the midbrain. Calcarine and P4 cortical branches are
shown.
System 2 vertebral arteries, basilar arteries and their branches,Vertebral artery arisis from the subclavian artery goes posterosuperiorly
Sinuses lie outside the dura//Suerficial cerebral veins lie in subarachnoid space and drain the cerebrum
//deep veins drain the periventricular subcortical white matter
SSS IS THE Principle sinus is seen superficially in the falx cerebrian astomotic vein of trolard syllcvian fissure//it follows the longitudinal fissure posteriorly ending at the confluenne of sinuses
The transverse sinus follows the groove from tentorium cerebelli to form sigmoidsinus// The superficial cereberal veins inferiorly joins the cavernous sinus
CSs contain the two cavernous internal carotid arteries (ICAs) and 3,4,6 part of 5 th
Internal cerebral veins which lie below splenium of corpus callosum and oin above the cerebellum to form the great cerebellar vein
