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The midbrain tegmentum is the portion of the midbrain ventral to the cerebral aqueduct, and is much larger in size than the tectum. It communicates with the cerebellum by the superior cerebellar peduncles , which enter at the caudal end, medially, on the ventral side; the cerebellar peduncles are distinctive at the level of the inferior ...
The isthmic organizer, or isthmus organizer, also known as the midbrain−hindbrain boundary (MHB), is a secondary organizer region that develops at the junction of the midbrain and metencephalon (embryonic hindbrain). [1] The MHB expresses signaling molecules that regulate the differentiation and patterning of the adjacent neuroepithelium.
View of the midbrain showing covering tectum and tegmental floor. The midbrain is further subdivided into three parts: tectum, tegmentum, and the ventral tegmental area. The tectum forms the ceiling. The tectum comprises the paired structure of the superior and inferior colliculi and is the dorsal covering of the cerebral aqueduct.
The human brain is primarily composed of neurons, glial cells, neural stem cells, and blood vessels. Types of neuron include interneurons, pyramidal cells including Betz cells, motor neurons (upper and lower motor neurons), and cerebellar Purkinje cells. Betz cells are the largest cells (by size of cell body) in the nervous system. [40]
Cerebral blood flow (CBF) is the blood supply to the brain in a given period of time. [8] In an adult, CBF is typically 750 millilitres per minute or 15.8 ± 5.7% of the cardiac output . [ 9 ] This equates to an average perfusion of 50 to 54 millilitres of blood per 100 grams of brain tissue per minute.
Cross-section of the midbrain. Tectum. Corpora quadrigemina. Inferior colliculi; Superior colliculi; Pretectum; Tegmentum. Periaqueductal gray; Rostral interstitial nucleus of medial longitudinal fasciculus; Midbrain reticular formation; Dorsal raphe nucleus; Red nucleus; Ventral tegmental area. Parabrachial pigmented nucleus; Paranigral ...
The endothelial cells in the cerebral blood vessel walls are joined tightly to one another, forming the blood–brain barrier, which blocks the passage of many toxins and pathogens [35] (though at the same time blocking antibodies and some drugs, thereby presenting special challenges in treatment of diseases of the brain). [36]
This development section covers changes in brain structure over time. It includes both the normal development of the human brain from infant to adult and genetic and evolutionary changes over many generations. Neural development in humans; Neuroplasticity – changes in a brain due to behavior, environment, aging, injury etc.