Brain School _Cerebrovascular Embryology_ by MedMaterials

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									Cerebrovascular Embryology
     October 6, 2000
           Brain School
   Resident: Dr. Charles Matouk
   Supervisor: Dr. Chris Wallace
Primitive Aortic Arches
                Key Points
                1) Cephalic location
                    of primitive heart
                2) 6 pairs of
                    primitive aortic
                    arches
                3) Thoracic
                    migration of heart
                    and step-wise
                    arch regression
Primitive Aortic Arches
                Major Events
                1) Regression of
                    dorsal aorta
                    between 3rd and
                    4th arches
                2) Derivation of
                    subclavian
                    arteries from 6th
                    intersegmental
                    arteries
                3) Attenuation of R
                    4th aortic arch
4-mm Fetal Stage
            1st arch – involution
                  and mandibular
                  artery remnant
            2nd arch – involution
                  and hyoid artery
                  remnant
            3rd arch – precursor of
                  ICA and ECA
4-mm Fetal Stage
            Cranial division of
                primitive ICA –
                primitive ACA
            Caudal division –
                precursor of
                PComA

            ACA is the direct
               embryonic
               continuation of
               ICA, not MCA!!!
4-mm Fetal Stage
            In hindbrain, arterial
                 vasculature
                 defined by paired,
                 separate
                 longitundinal
                 nerual plexi

            Supplied by
                anastomotic
                branches of
                primitive ICA and
                C1 segmental
                artery, and others
Embryonic Carotid-Basilar
     Anastomoses
                 1)   Persistent
                      trigeminal artery
                 2)   Otic artery
                 3)   Hypoglossal
                      artery
                 4)   Proatlantal
                      intersegmental
                      artery
5-6-mm Fetal Stage
             Ventral pharnygeal
                 artery (precursor
                 of proximal ECA
                 vasculature) now
                 prominent

             Caudal division of ICA
                forms
                anastomoses
                with cranial-end
                of bilateral
                longitudinal
                neural arteries
7-12-mm Fetal Stage
             Ventral pharyngeal
                 system more
                 extensive with
                 identifiable
                 branches
                 (precursor of
                 proximal ECA)

             Hyoid artery
                 (precursor of
                 upper portion of
                 ECA)
7-12-mm Fetal Stage
             Vertebral arteries
                 formed by
                 coalescence of
                 longitudinal
                 anastomoses
                 between cervical
                 segmental
                 arteries
   Drapkin AJ. The double lumen sign: a
 pathognomonic sign of arterial dissection?
Diagnostic Neuroradiology 42:203-205;2000.
12-14-mm Fetal Stage
              Plexiform anastomosis
                   between ACAs
                   evolve into
                   AComA
16-18-mm Fetal Stage
              Stapedial artery
                  (branch of hyoid
                  artery) at zenith
                  of development)

              Its development
                   defines distal
                   ECA circulation
                   and middle
                   meningeal artery.
16-18-mm Fetal Stage
              Fate of stapedial
                  artery … proximal
                  trunk regression
                  with annexation
                  of territories by
                  ventral
                  pharnygeal trunk
                  and ophthalmic
                  arteries
Evolution of Primitive
Ophthalmic Arteries
                1)   Ventral (from
                     ACA) ophthalmic
                     artery
                2)   Dorsal
                     ophthalmic artery

                When dorsal persists
                   or is dominant,
                   ophthalmic artery
                   originates from
                   cavernous
                   segment of ICA
Evolution of Posterior
     Circulation
                PCA arising from ICA,
                   predominantly or
                   exclusively, is
                   described as
                   being of ‘fetal
                   origin’
Review
Review
Review
Review
               References
1. Morris, P. Practical Angiography. 1997. Williams
   & Wilkins, Baltimore, Maryland. Chapter 5, pp 89-
   98.
2. Osborn, A. Diagnostic Neuroradiology. 1994.
   Mosby, St. Louis, Missouri. Chapter 6, pp 117-153.
3. Moore KL and Persaud TVN. 1998. W.B.
   Saunders Company, Philadelphia, Pennsylvania.
   Chapter 349-403.

								
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