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  Frog brain model (dorsal view)

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This image shows some of the major structures visible on the dorsal surface of the frog brain. The vertebrate brain is divided into three main regions, some of which are further subdivided. Anterior most is the forebrain, which is divided into the telencephalon and diencephalon. The mid brain, or mesencephalon, develops without  further subdivision. The hindbrain differentiates into the metencephalon and myelencephalon. The anterior-most telencephalon bears two olfactory lobes (1) and two cerebral hemispheres (2). The olfactory lobes terminate in the olfactory nerves, which carry impulses from the nasal cavities to the brain.

 

The mesencephalon, immediately posterior to the diencephalon, bears two large optic lobes (3) that serve to integrate nerve impulses from the eyes. Note that the optic lobes of the frog are large, which reflects the importance of sight to these visual predators. Posterior to the mesencephalon is the metencephalon, which is represented by a narrow, transverse portion of the brain called the cerebellum (4); the cerebellum is involved in motor coordination in the frog.

 

The most posterior portion of the brain is the myelencephalon, consisting of the medulla oblongata (5) that tapers gradually into the spinal cord. A depression between the two sides of the medulla oblongata called the choroid plexus (6) is partially responsible for the secretion of the lymph-like cerebrospinal fluid that fills spaces called ventricles in the brain and the central canal of the spinal cord.

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