During which weeks do the neural flexures form?

During which weeks do the neural flexures form?

• A. Between the 1st and 3rd weeks
• B. Between the 4th and 8th weeks
• C. Between the 9th and 12th weeks
• D. Between the 14th and 16th weeks

Answer: (B)

Neural flexures form as the neural tube is bending to create the brain’s regional architecture. The first bends, the cephalic (mesencephalic) and cervical flexures, appear around the fourth week as the forebrain starts to curve and the connection to the spinal cord establishes. A bit later, the pontine (secondary) flexure forms as the hindbrain and brainstem regions expand, typically around weeks five to six. By the end of the eighth week these major bends are in place, giving the brain its characteristic shape. So the developmental window when these flexures form is from the fourth through the eighth week. Weeks earlier are before bending begins, and after the eighth week the major flexures have largely established.

Neural flexures form as the neural tube is bending to create the brain’s regional architecture. The first bends, the cephalic (mesencephalic) and cervical flexures, appear around the fourth week as the forebrain starts to curve and the connection to the spinal cord establishes. A bit later, the pontine (secondary) flexure forms as the hindbrain and brainstem regions expand, typically around weeks five to six. By the end of the eighth week these major bends are in place, giving the brain its characteristic shape. So the developmental window when these flexures form is from the fourth through the eighth week. Weeks earlier are before bending begins, and after the eighth week the major flexures have largely established.