12/18/2023 0 Comments Cephalic flextureInitially there are three primary brain vesicles: prosencephalon, mesencephalon, and rhombencephalon. ![]() What are the three primary brain vesicles? In the adult, this region has functions associated with vision, hearing, motor control, sleep/wake, arousal (alertness), and temperature regulation. Mesencephalon (midbrain) forms the adult tectum, cerebral peduncle, pretectum and cerebral aqueduct. Herein, what does the Mesencephalon become? The pontine flexure, which develops into the transverse rhombencephalic sulcus, separates the metencephalon and the myelencephalon. Similarly, what is the constriction that separates the Mesencephalon from the Metencephalon? The cephalic flexure lies between the mesencephalon and rhombencephalon. cephalic flexure the curve in the mid- brain of the embryo. caudal flexure the bend at the aboral end of the embryo. The caudal part of the midbrain and the rostral part of the hindbrain makes up a mibrain-hindbrain boundary region known as the isthmic organizer.įlexure. From Larsen (12).The cephalic flexure also known as the mesencephalic flexure, is the first flexure or bend that forms between the midbrain and hindbrain. Formation of the cranial flexures: Final configuration is shown. The roof of the mesencephalon becomes thinned as a result of the pontine flexure and produces the roof of the fourth ventricle.įormation of the flexures: Shown are the three flexures that have formed by the fifth embryonic week. Pontine flexure: A third flexure, the pontine flexure, occurs during the fifth embryonic week between the mesencephalic and cervical flexures and is concave ventrally.Cervical flexure: The cervical flexure occurs at the junction of the metencephalon and spinal cord.Mesencephalic flexure: The mesencephalic flexure occurs around the mesencephalon.From Larsen (12).Ĭoncave bending of the neuraxis (primary flexures) occurs during the fourth embryonic week. Myelencephalon: The myelencephalon develops into the medulla.įormation of the secondary vesicles: Shown are the five secondary vesicles that form during the fifth embryonic week. ![]() Metencephalon: The metencephalon forms the pons and cerebellum.Mesencephalon: The mesencephalon remains unchanged and gives rise to the tectum (superior and inferior colliculi), midbrain tegmentum, and cerebral peduncles.Diencephalon: The diencephalon develops into the hypothalamus, thalamus, epithalamus, neural retina, and pineal body.Telencephalon: The telencephalon forms the cerebrum and basal ganglia.From Larsen (12).ĭuring the fifth embryonic week, five secondary vesicles develop from the primary vesicles: Prosencephalon – two secondary vesicles The cranial neural tube during the fourth embryonic week divides into three morphologically and histochemically distinct primary vesicles:įormation of the primary vesicles: Formation and progression of the mesencephalic and cervical flexures are shown. The spinal cord is caudal to the myelencephalon and remains unsegmented. ![]() The formation of the cranial vesicles and flexures provides further development and segmentation of the brain and occurs in two phases ( 3, 10, 11, 12).
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