What are the primary brain vesicles and what do they develop into?

By the end of the 4th week, the neural tube forms three primary brain vesicles: Prosencephalon (Forebrain), which divides into Telencephalon and Diencephalon; Mesencephalon (Midbrain), which remains undivided; and Rhombencephalon (Hindbrain), which divides into Metencephalon and Myelencephalon. These give rise to all adult brain regions and the ventricular system.

How do the brain ventricles develop from the brain vesicles?

The cavities of the brain vesicles develop into specific ventricles: Lateral Ventricles from the Telencephalon, Third Ventricle from the Diencephalon, Cerebral Aqueduct from the Mesencephalon, and Fourth Ventricle from the Rhombencephalon. Openings in the fourth ventricle allow CSF to enter the subarachnoid space.

What are the flexures of the brain and what is their role in development?

Three flexures shape the brain's curvature: Cephalic Flexure at the midbrain level, bending ventrally; Cervical Flexure between the hindbrain and spinal cord, forming a 90° angle; and Pontine Flexure divides the hindbrain into pons and medulla, forming the diamond-shaped fourth ventricle.

What clinical conditions are associated with ventricular development?

Two key conditions are: Hydrocephalus, which is CSF buildup due to overproduction or blockage, leading to ventricular dilation and an enlarged head; and Dandy-Walker Syndrome, which involves blocked 4th ventricle apertures, causing a dilated 4th ventricle, cerebellar vermis agenesis, and occipital meningocele.

How does the hindbrain (rhombencephalon) develop into adult structures?

The hindbrain divides into: Myelencephalon, which forms the medulla oblongata; and Metencephalon, which forms the pons and cerebellum. Basal and alar laminae contribute to cranial nuclei, and the cerebellum forms from rhombic lips.

What structures develop from the forebrain (prosencephalon)?

The forebrain divides into: Diencephalon, forming thalamus, hypothalamus, subthalamus, epithalamus, and the third ventricle; and Telencephalon, forming cerebral hemispheres and lateral ventricles, with growth in a C-shaped pattern.

Are neurons formed after birth, and what is unique about brain structure development?

All neurons are formed before birth, with no postnatal neurogenesis. Structures like the lateral ventricle and corpus callosum develop in a C-shape due to the growth of the cerebral hemispheres.

Brain Development – Vesicles to Cerebral Hemispheres

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