Common (CCA), internal (ICA), and external (ECA) carotid arteries; vertebral artery (VA)

CCA terminates by dividing into ECA and ICA

ECA is smaller of 2 terminal branches

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  Supplies most of head and neck (except eye, brain)

  
  
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  Has numerous anastomoses with ICA and VA (may become important source of collateral blood flow)

ICA has no normal extracranial branches

CCA

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  Right CCA originates from brachiocephalic trunk; left CCA originates from aortic arch

  
  
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  Courses superiorly in carotid space, anteromedial to internal jugular vein

  
  
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  Divides into ECA and ICA at ~ C3-C4 level

Cervical ICA

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  90% are posterolateral to ECA

  
  
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  Carotid bulb

  
  
  
  
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    Focal dilatation of ICA at its origin from CCA

    
    
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    Flow reversal occurs in carotid bulb

  
  
  
  
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  Ascending cervical segment

  
  
  
  
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    Courses superiorly within carotid space

    
    
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    Enters carotid canal (petrous temporal bone)

    
    
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    No named branch in neck

  
  

ECA

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  Smaller and medial compared with ICA

  
  
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  Has 8 major branches in neck

  
  
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  Superior thyroid artery

  
  
  
  
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    1st ECA branch (may arise from CCA bifurcation)

    
    
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    Arises anteriorly, courses inferiorly to apex of thyroid

    
    
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    Supplies superior thyroid and larynx

    
    
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    Anastomoses with inferior thyroid artery (branch of thyrocervical trunk)

  
  
  
  
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  Ascending pharyngeal artery

  
  
  
  
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    Arises from posterior ECA (or CCA bifurcation)

    
    
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    Courses superiorly between ECA and ICA

    
    
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    Visceral branches, muscular branches, and neuromeningeal branches

  
  
  
  
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  Lingual artery

  
  
  
  
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    2nd anterior ECA branch

    
    
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    Loops anteroinferiorly, then superiorly, to tongue

    
    
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    Major vascular supply to tongue, oral cavity, and submandibular gland

  
  
  
  
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  Facial artery

  
  
  
  
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    Originates just above lingual artery

    
    
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    Curves around mandible, then passes anterosuperiorly across cheek and is closely related to submandibular gland

    
    
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    Supplies face, palate, lip, and cheek

  
  
  
  
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  Occipital artery

  
  
  
  
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    Originates from posterior aspect of ECA

    
    
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    Courses posterosuperiorly between occiput and C1

    
    
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    Supplies scalp, upper cervical musculature, and posterior fossa meninges

  
  
  
  
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  Posterior auricular artery

  
  
  
  
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    Arises from posterior ECA above occipital artery

    
    
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    Courses superiorly to supply pinna, scalp, external auditory canal, and chorda tympani

  
  
  
  
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  Superficial temporal artery

  
  
  
  
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    Smaller of 2 terminal ECA branches

    
    
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    Runs superiorly behind mandibular condyle, across zygoma

    
    
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    Supplies scalp and gives off transverse facial artery

  
  
  
  
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  Internal maxillary artery

  
  
  
  
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    Larger of 2 terminal ECA branches

    
    
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    Arises within parotid gland, behind mandibular neck

    
    
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    Gives off middle meningeal artery (supplies cranial meninges)

  
  

Normal ultrasonography appearances of carotid arteries

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  CCA diameter: 6.3 ± 0.9 mm, smooth and thin intima, antegrade low-resistance arterial flow

  
  
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  ICA diameter: 4.8 ± 0.7 mm, smooth and thin intima, antegrade low-resistance flow

  
  
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  ECA diameter: 4.1 ± 0.6 mm, smooth and thin intima, antegrade high-resistance flow

In assessing carotid arteries on ultrasonography, the following parameters should be examined

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  Intimal-medial thickness

  
  
  
  
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    Distance between leading edges of lumen-intima interface and media-adventitia interface at far edge

    
    
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    0.5-1.0 mm in healthy adults

  
  
  
  
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  Presence of atherosclerotic plaques

  
  
  
  
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    Eccentric/concentric, noncircumferential/circumferential

    
    
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    Calcified plaque/soft plaque

  
  
  
  
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  Luminal diameter/area reduction

  
  
  
  
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    Should be measured on true cross-sectional view of affected artery

    
    
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    Color flow helps to detect residual lumen in tight stenosis or in assessing indeterminate total occlusion

  
  
  
  
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  Spectral Doppler analysis

  
  
  
  
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    Arterial flow pattern: Low-resistance/high-resistance flow, antegrade/retrograde flow, special waveform (e.g., damped waveform, preocclusive “thump”)

    
    
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    Peak systolic velocity measurement

    
    
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    Systolic velocity ratio measurement

  
  

Scanning technique must be meticulous to produce reliable Doppler ultrasound results

Obliquity of imaging plane in relation to cross section of artery may wrongly estimate degree of stenosis

Consider acute idiopathic carotidynia: Tender mass around distal carotid, near bifurcation

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  Vessel wall thickening, no luminal narrowing or velocity elevation