Which statement best describes boundary layer separation in the carotid bulb?
A) Flow moves forward on the wall opposite the flow divide between the internal and external carotid arteries.
B) Both forward and reverse flow patterns are present as a result of dilatation of the carotid bulb and the presence of a pressure-flow gradient on the posterolateral wall of the bulb.
C) Forward flow is seen on the wall opposite the flow divide, whereas reverse flow is seen on the anterolateral wall of the bulb.
D) Disordered flow patterns are seen in the carotid bulb as a result of thickening of the arterial intima.

Question

Quizplus · Accepted Answer

Boundary layer separation occurs because of the dilatation of the carotid bulb compared to the diameter of the CCA and ICA. This change in geometry results in low pressure on the wall of the bulb opposite the flow divide (the wall between the ICA and ECA). Blood normally flows from high-pressure to low-pressure regions. Although the direction of movement of blood cells along the flow divide wall is toward the brain, cells in the flow stream approaching the posterior wall of the bulb (opposite the flow divide) separate from the forward stream and seek the low-pressure zone. This change in flow direction is called boundary layer separation. As a result, multiple flow patterns are found within the normal carotid bulb.

Which Statement Best Describes Boundary Layer Separation in the Carotid